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Monitoring and Modeling Water and Nitrogen Transport in the Vadose Zone of a Vegetable Farm in the Suwannee River Basin


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MONITORING AND MODELING WATER AND NITROGEN TRANSPORT IN THE VADOSE ZONE OF A VEGETABLE FARM IN THE SUWANNEE RIVER BASIN By FRANK WARREN MCKINNIE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2003

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Copyright 2003 by Frank Warren McKinnie

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This document is dedicated to my family and friends

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iv ACKNOWLEDGMENTS First, I would like to thank my graduate committee chairperson, Dr. Wendy Graham, who has helped me gain so much knowledge from this experience and whose assistance throughout my time in graduate school has exceeded all my expectations. I would also like to thank all my family and friends who have made the past five years in Gainesville, FL, at the University of Florida one of the best experiences of my life. Special thanks go to my mother, father, grandmother, and brother for their continual love, support, and encouragement throughout my time in graduate school and my life. I would also like to thank Ken and Joe Hall for their assistance and cooperation with the research project; Dr. James Jones, Dr. Jennifer Jacobs, and Dr. Donald Graetz for serving on my committee and for their assistance and guidance; Mike Albert, Jeff Williams, and Wayne Williams for their assistance on the research project both on and off the field; Dawn Lucas for analyzing all those soil samples; all my professors for their dedication to teaching and research; Cheryl Porter for a ssistance with the DSSAT modifications; and all the faculty and staff at the Agricultura l and Biological Engineering Department.

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v TABLE OF CONTENTS Page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES...........................................................................................................viii LIST OF FIGURES...........................................................................................................ix CHAPTER 1 INTRODUCTION........................................................................................................1 Background ...................................................................................................................1 Objectives .....................................................................................................................3 Literature Review .........................................................................................................3 Suwannee River Basin ...........................................................................................3 Nitrogen Cycle .......................................................................................................5 Potato Crop Management ......................................................................................7 2 FIELD EXPERIMENTS AND METHODOLOGIES................................................13 Site Description ..........................................................................................................13 Field Sampling Methodologies ...................................................................................14 Field Results ...............................................................................................................17 Spring 2001 Potato Crop .....................................................................................18 Planting details, crop management, and weather .........................................18 Moisture content results ...............................................................................19 Nitrate-nitrogen results .................................................................................21 Crop monitoring results ................................................................................24 Spring 2002 Potato Crop .....................................................................................26 Planting details, crop management and weather ..........................................26 North half moisture content results ..............................................................27 South half moisture content results ..............................................................29 North half bed nitrate-nitrogen results .........................................................31 South half bed nitrate-nitrogen results .........................................................35 North half furrow nitrate-nitrogen results ....................................................37 South half furrow nitrate-nitrogen results ....................................................38 Crop monitoring ...........................................................................................42 Comparisons of Final Yield/Nitr ogen Lost and Nitrogen Applied ............................44

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vi 3 MODEL DESCRIPTION AND RESULTS...............................................................47 DSSAT Model Description .........................................................................................47 Hydrology Component ........................................................................................48 Nitrogen Component ...........................................................................................50 Crop Growth Component ....................................................................................51 Model Calibration and Results ...................................................................................53 4 DSSAT MODIFICATIONS.......................................................................................67 HYDRUS Model Description .....................................................................................68 Governing Flow Equation ...................................................................................69 Root Water Uptake ..............................................................................................70 The Unsaturated Soil Hydraulic Properties .........................................................71 Governing Transport Equation ............................................................................72 HYDRUS Results and DSSAT Modifications ...........................................................74 HYDRUS Results ................................................................................................74 DSSAT Modifications .........................................................................................81 5 MODIFIED DSSAT RESU LTS AND DISCUSSION...............................................85 Soil-Water Transport Results .....................................................................................85 2001 Potato Crop .................................................................................................85 2002 Potato Crop .................................................................................................89 Nitrate-Nitrogen Transport Results ............................................................................93 2001 Potato Crop .................................................................................................93 2002 Potato Crop .................................................................................................96 Crop Growth Results ..................................................................................................99 2001 Potato Crop .................................................................................................99 2002 Potato Crop ...............................................................................................102 6 CONCLUSIONS......................................................................................................108 APPENDIX A SOIL SAMPLE ANALYSIS RESULTS..................................................................115 B PLANT SAMPLE ANALYSIS RESULTS..............................................................136 C SUBSTOR/DSSAT INPUT FILES..........................................................................140 D HYDRUS INPUT FILES.........................................................................................156 E DSSAT MODIFICATIONS.....................................................................................212 F MODIFIED DSSAT/SU BSTOR INPUT FILES......................................................216 LIST OF REFERENCES .................................................................................................229

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vii BIOGRAPHICAL SKETCH...........................................................................................233

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viii LIST OF TABLES Table page 2-1. Retentivity data measured at the research site.........................................................14 2-2. Spring 2001 potato crop planting in formation obtained from farmer......................18 2-4. Statistical analysis of 2001 north half soil samples moisture content results..........20 2-5. Important dates related to planting, ha rvest, and phenological events (2001).........24 2-6. Spring 2002 approximate nitrogen fertilizer schedule and amounts........................27 2-7. The standard deviations of the 2002 north half measured volumetric moisture contents.....................................................................................................................29 2-8. The standard deviations of the 2002 s outh half measured moisture contents..........31 2-9. Nitrate-nitrogen content results for north soil samples taken on May 1, 2002 for wells.........................................................................................................................3 4 2-10. Statistical analysis of spring 2002 furro w soil samples nitrate-nitrogen results......40 2-11. Important dates related to planting, ha rvest, and phenological events (2002).........42 A-1. Soil sample results at the project site.....................................................................116 B-1. Potato crop analysis results (2001).........................................................................137 B-2. Potato crop analysis results (2002).........................................................................138

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ix LIST OF FIGURES Figure page 1-1. Suwannee River Basin (Pittman et al., 1997).............................................................1 2-1. North half average moisture contents for the spring 2001 potato crop....................19 2-2. Average 2001 north half nitrate-nitrogen content in top 90 cm of the bed area......22 2-3. North half cumulative nitrogen ap plied and total crop uptake (2001).....................26 2-4. North half average volumetric moisture contents for the spring 2002 potato crop in the center of bed...................................................................................................28 2-5. South half average volumetric moisture contents for the spring 2002 potato crop in the center of bed...................................................................................................30 2-6. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center of bed........................................................................................................................3 2 2-7. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center of bed........................................................................................................................3 5 2-8. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center of furrow...................................................................................................................38 2-9. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center of furrow...................................................................................................................39 2-10. Nitrogen applied and to tal crop uptake (2002).........................................................44 2-11. Comparison between the total nitroge n applied and the dry tuber yield..................45 3-1. DSSAT spring 2001 potato crop soil moisture content results for the north half at 0-15 cm.....................................................................................................................55 3-2. DSSAT spring 2001 potato crop soil moisture content results for the north half at 15-30 cm...................................................................................................................56 3-3. DSSAT spring 2001 potato crop soil moisture content results for the north half at 30-60 cm...................................................................................................................56

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x 3-4. DSSAT spring 2001 potato crop soil moisture content results for the north half at 60-90 cm...................................................................................................................57 3-5. Cumulative water balance for the north half of the field for the spring 2001 potato crop........................................................................................................................... 58 3-6. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 0-15 cm...................................................................................................60 3-7. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 15-30 cm.................................................................................................60 3-8. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 30-60 cm.................................................................................................61 3-9. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 60-90 cm.................................................................................................61 3-10. DSSAT dry leaf weight predictions for the spring 2001 potato crop on the north half of the field.........................................................................................................63 3-11. DSSAT dry stem weight predictions for the spring 2001 potato crop on the north half of the field.........................................................................................................64 3-12. DSSAT dry tuber weight predictions for the spring 2001 potato crop on the north half of the field.........................................................................................................64 3-13. Cumulative nitrogen balance for the spring 2001 potato crop on the north half of the field.....................................................................................................................6 5 4-1. Illustrations of the potato plant beds (01/28/2003) and root distribution (04/12/2003).............................................................................................................67 4-2. SMCC of the hydraulic conductivity versus moisture content using the Brooks and Corey equation...................................................................................................76 4-3. SMCC of the soil matric potential versus moisture content for the top 45 cm of the soil profile using the Brooks and Corey equation..............................................76 4-4. SMCC of the soil matric potential versus moisture content for the bottom 45 cm of the soil profile using the Brooks and Corey equation..........................................77 4-5. Flat upper boundary nitrate concentration spectral map for the top 90 cm on the north half of the field for 01/10/02 through 01/14/02 (a-e)......................................79 4-6. Irregularly shaped upper boundary nitrate concentration spectral map for the top 90 cm on the north half of the fi eld for 01/10/02 through 01/14/02 (a-e)................80

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xi 4-7. Cumulative nitrate-nitrogen leached out of the top 90-cm from the January 10, 2002 fertilizer application........................................................................................81 4-8. A comparison of the light interception and root domain for flat (a) and bedded (b) rows..........................................................................................................................8 3 4-9. Potato plant canopy illustration................................................................................84 5-1. Comparisons between the predicted and measured moisture contents at 0-15 cm for the north half of the field 2001 potato crop........................................................86 5-2. Comparisons between the predicted and measured moisture contents at 15-30 cm for the north half of the field 2001 potato crop........................................................87 5-3. Comparisons between the predicted and measured moisture contents at 30-60 cm for the north half of the field 2001 potato crop........................................................87 5-4. Comparisons between the predicted and measured moisture contents at 60-90 cm for the north half of the field 2001 potato crop........................................................88 5-5. Cumulative water balance for the north half of the field for the spring 2001 potato crop........................................................................................................................... 88 5-6. Comparisons between the predicted and measured moisture contents at 0-15 cm for the 2002 potato crop...........................................................................................90 5-7. Comparisons between the predicted and measured moisture contents at 15-30 cm for the 2002 potato crop...........................................................................................90 5-8. Comparisons between the predicted and measured moisture contents at 30-60 cm for the 2002 potato crop...........................................................................................91 5-9. Comparisons between the predicted and measured moisture contents at 60-90 cm for the 2002 potato crop...........................................................................................91 5-10. Cumulative water balance for the north half of the field for the spring 2002 potato crop........................................................................................................................... 92 5-11. Cumulative water balance for the south half of the field for the spring 2002 potato crop........................................................................................................................... 93 5-12. Comparisons between the predicted and measured nitrate-nitrogen contents at 0-15 cm for the north half of the field (2001)..........................................................94 5-13. Comparisons between the predicted and measured nitrate-nitrogen contents at 15-30 cm for the north half of the field (2001)........................................................94 5-14. Comparisons between the predicted and measured nitrate-nitrogen contents at 30-60 cm for the north half of the field (2001)........................................................95

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xii 5-15. Comparisons between the predicted and measured nitrate-nitrogen contents at 60-90 cm for the north half of the field (2001)........................................................95 5-16. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 0-15 cm (2002).....................................................................................................97 5-17. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 15-30 cm (2002)...................................................................................................97 5-18. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 30-60 cm (2002)...................................................................................................98 5-19. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 60-90 cm (2002)...................................................................................................98 5-20. Cumulative nitrogen balance for the 2001 potato crop on the north half of the field.........................................................................................................................1 00 5-21. Dry leaf weight predictions for the spring 2001 potato crop on the north half of the field...................................................................................................................100 5-22. Dry stem weight predictions for the spring 2001 potato crop on the north half of the field...................................................................................................................101 5-23. Dry tuber weight predictions for the spring 2001 potato crop on the north half of the field...................................................................................................................101 5-24. North half cumulative nitrogen balance for the2002 potato crop..........................103 5-25. South half cumulative nitrogen balance for the 2002 potato crop.........................103 5-26. North half dry leaf weight pred ictions for the spring 2002 potato crop.................104 5-27. South half dry leaf weight pred ictions for the spring 2002 potato crop.................104 5-28. North half dry stem weight pred ictions for the spring 2002 potato crop...............105 5-29. South half dry stem weight pred ictions for the spring 2002 potato crop...............105 5-30. North half dry tuber weight pred ictions for the spring 2002 potato crop...............106 5-31. South half dry tuber weight pred ictions for the spring 2002 potato crop...............106

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xiii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering MONITORING AND MODELING WATER AND NITROGEN TRANSPORT IN THE VADOSE ZONE OF A VEGETABLE FARM IN THE SUWANNEE RIVER BASIN By Frank Warren McKinnie August 2003 Chair: Wendy D. Graham Major Department: Agricultural and Biological Engineering The Suwannee River Basin has become a source of major concern over recent years due to the increased nitrogen loads within the basin. In 1995, nitrate loads increased from 2,300 to 6,000 kg/day over a 53.1 km reach of the Suwannee River that began in Dowling Park, FL and ended in Branford, FL Eighty-nine percent of the increase occurred in the lower 2/3 of the reach. With the increasing nitrogen loads, it is evident that serious problems may arise if nothing is done to correct the current situation. The ultimate goal of this research was to develop Best Management Practices (BMPs) to reduce nutrient loadings to the ground water from vegetable farms in the Suwannee River Basin. To achieve the objective, nitrogen and water transport in the vadose zone was monitored and modeled under a 56.7 ha center pivot at a 2020 ha vegetable farm just west of OBrien, FL. This farm lies just a few miles from the Suwannee River in the upstream direction of ground water flow. The sandy soils on the

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xiv farm are extremely susceptible to leaching nitrogen out of the vadose zone and into the underlying Floridan Aquifer. Monitoring well samples, soils samples, and plant samples was used to obtain onsite nitrogen, plant, and soil moisture information over time to track nitrogen movement and calibrate mathematical models. The measured data show that the sandy soils at the project are highly susceptible to leaching nitrate-nitrogen following rainfall events and irrigation applications. The data collected in 2001 show that 24% of the total nitrogen applied (fertilizer plus irrigation nitrate-nitrogen) to the north half of the field was recovered by the potato plants, leaving 325 kg/ha of the 427 kg/ha nitrogen applied in the fertilizer and irrigation to be leached out of the soil profile and into the underlying Floridan Aquifer. The 2002 data indicate that the potato crops currently grown at the project site are receiving more than adequate amounts of nitrogen fertilizer and irrigation. The DSSAT35 crop model and the HYDRUS2D vadose zone model were used to produce an estimate of the total load and concentration of nitrogen and the quantity of water leaching through the vadose zone into the Floridan Aquifer. The DSSAT model significantly over predicted the volume of water drained out of the top 90 cm, which directly affects the nitrate-nitrogen leaching. As a results, the 2001 potato crop simulation results show that the DSSAT model under predicted the dry tuber yield by 3,105 kg/ha relative to the 6,840 kg/ha measured. These results indicate that DSSAT is unable to accurately predict potato crop growth on sandy soils located at the project site. Results from the 2001 calibration and from the HYDRUS simulations illustrate the importance of incorporating multi-dimensional water and nutrient transport and the need to replace or improve upon the current methods implemented by the DSSAT plant model.

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1 CHAPTER 1 INTRODUCTION Background The Suwannee River Basin, shown in Figure 1-1, has become a source of major concern over recent years due to increased nitrogen loads within the basin. The sandy soils located in the basin are susceptible to nitrogen leaching into the underlying Floridan Aquifer. In 1995, Pittman et al. (1997) conducted a study, during base flow, on a 53.1 km reach of the Suwannee River that began in Dowling Park, FL, and ended in Branford, FL (Figure 1-1). Figure 1-1. Suwannee River Basin (Pittman et al., 1997)

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2 Results from the study showed that the nitrogen loads increased from 2,300 kg/day to 6,000 kg/day over the entire reach with 89% of the increase occurring in the lower 2/3 of the reach. Ham and Hatzell (1996) found that nitrate concentrations in the Suwannee River increased at a rate of 0.02 mg/L per year over a twenty-year period from 19711991. The source of the increased nitrogen loads is not evident because of several possible non-point sources of the pollution, which include dairy farms, row-crop farms, poultry farms, residential communities, etc. The waters in the basin are used for recreation, a potable water source, and support an intricate diverse ecosystem. With the increasing nitrogen loads, it is evident that serious problems may eventually arise if nothing is done to alleviate the current problem. In an attempt to determine the possible sources of the increased nitrogen loads, a joint research venture involving the University of Florida, Suwannee River Water Management District (SRWMD), the Florida Department of Agricultural and Consumer Services (FDACS), and the Florida Department of Environmental Protection (FDEP) was developed. The overall purpose of the study was to evaluate nitrate loadings from three different agricultural operations (including a dairy farm, poultry farm, and row-crop farm) to the Floridan Aquifer. The primary focus of the research reported here is the study conducted at the row-crop operation located in OBrien, FL, approximately 16-km northwest of Branford, FL (Figure 1-1). The cultivars grown on the 2,020-ha farm include crops such as corn, peanuts, soybean, potatoes, etc. Several of the crops grown on the farm are known to have poor recovery of applied nitrogen. Of these crops, potatoes appear to contribute a large amount of the cumulative nitrogen being leached out of the vadose zone and into the Floridan Aquifer (Albert, 2002).

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3 In an effort to evaluate and reduce the amount of nitrogen being leached out of the soil profile, potato crops have been studied since spring 2001. By studying the system and processes that influence the nitrogen and water transport, a better understanding of the system can be developed that can aid in the development of an effective best management practice (BMP). Objectives The objectives of this research included monitoring nitrate and water transport in the vadose zone on a 56.7 ha potato field located at Pivot 12 of the research farm, and implementing a mathematical model that can accurately predict the spatial and temporal distribution of nitrate and water in the soil profile as well as crop yield. These objectives were developed to assist in reaching the goals outlined by the FDEP, FDACS, and SRWMD funded project to develop BMPs for the arable crops in the region. Literature Review Suwannee River Basin The Suwannee River basin comprises an area of 25,770 km2 with 43% of the total area located in north central Florida. The primary land use in the Florida portion of the basin is agriculture, including forestry, pasture, row crops, and intensive animal husbandry (Hornsby, 2000). The basin has several karst characteristics that result in a direct linkage between the surface and ground waters, resulting in a single dynamic flow system (Katz et al., 1996). As a result of the land use and direct interactions between surface and ground waters, there has been a noticeable increase in nitrate-nitrogen concentrations in surface and ground waters in the basin. Over the past 40 years, the nitrate-nitrogen concentrations in many of the springs in the Suwannee River basin have increased from less than 0.1 mg/L (Katz, 1992; Maddox et al., 1992) to more than 5 mg/L

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4 (Hornsby and Ceryak, 1999), which has resulted in high nitrogen loading rates in the Suwannee and Santa Fe Rivers (Katz, 2000). The total nitrate-nitrogen load in the basin in the 1998 water year was estimated to be 7,113 tons with 45.5% of the increase occurring in the middle Suwannee River Basin (Hornsby, 2000). The Suwannee River is the second largest river in Florida with a mean annual flow of 6.7 billion gallons per day, and is designated as an Outstanding Florida Water. Katz and Dehan (1996) found that the high nitrate-nitrogen levels in the Suwannee River and in parts of the Upper Floridan Aquifer were caused by the high nitrogen loading from the wastes generated by poultry and dairy farms, and fertilizers applied to cropland along the Suwannee River in Lafayette and Suwannee Counties. Ceryak and Hornsby (1996) reported that the median nitrate-nitrogen concentration of the ground water near the Suwannee River between Ellaville, FL and Branford, FL ranged from 0.5 mg/L to 4.0 mg/L. The high nitrate-nitrogen concentrations near Branford, FL were attributed to ground water discharge because there are no major stream inputs to the Suwannee River in this region of the middle Suwannee River Basin (Katz et al., 1999). Also, these researchers concluded that the elevated nitr ate-nitrogen concentrations during low flow periods increase the probability that the ground water inflow from springs and riverbed leakage were the cause of the increased nitrate concentrations and loads in the lower Suwannee River. These high nitrogen concentrations can eventually have detrimental effects on the Suwannee River basin ecosystem and on human health. Eutrophication can occur due to elevated nitrate-nitrogen concentrations in rivers, which results in algal blooms and depletion of dissolved oxygen in the water that can lead to fish kills. The Environmental

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5 Protection Agency (EPA) has set a maximum contaminant level (10 mg/L) for nitratenitrogen in drinking water to reduce the possibility of human health complications resulting from high nitrate-nitrogen concentrations. The limit was set because of the health risk to infants who consume high-nitrate water, who may contract methemoglobinemia (Mueller and Helsel, 1996). Nitrogen Cycle Elevated nitrogen concentrations in surface and ground waters have resulted in extensive studies related to nitrogen load contributions from many non-point sources of pollution. Leaching is the primary mechanism that contributes to the increased nitrogen loads, especially in sandy soils. But to fully understand nitrogen transport in the soil, the dynamics of the nitrogen cycle must be thoroughly understood. The nitrogen cycle is a complex system that has many factors that affect nitrogen transport. Nitrogen exists in soils as both inorganic and organic forms. Nitrogen sources for the soil include fertilizers, atmospheric nitrogen fixation by plants, nitrogen deposition by lightning, and animal waste. Nitrogen is primarily removed from the soil through leaching, but is also removed by eros ion and runoff, plant uptake of ammonium and nitrate, denitrification of nitrate, and volatization of ammonia. There are several chemical processes that affect nitrogen content in the soil, but the two microbial processes that primarily dictate the amount of nitrogen available for transport and plant availability of natural systems are mineralization and immobilization. Mineralization is the process by which ammonia is released from organic matter. Immobilization is the reverse reaction by which inorganic forms of nitrogen are converted to organic forms. Inorganic forms of nitrogen are the most common forms of fertilizer used by farming operations and are the most susceptible to chemical transport. Typical forms of inorganic

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6 nitrogen used as fertilizer are ammonium, anhydrous ammonia, urea, and ammoniumnitrate. Some inorganic fertilizers go through chemical transformations, which make nitrogen readily available to plants. For instance, ammonium is a compound transformed by a process that is termed nitrification into nitrate, which is the form of nitrogen that is more available to plants compared to NH4 + sources (Roberts et al., 1991). Nitrification is the process by which ammonium (NH4 +) is transformed into nitrate (NO3 -). The process is a two-step reaction that requires autotrophic bacteria (Nitrosomonas) to convert NH4 + to nitrite (NO2 -). Then, a second group of autrophs (Nitrobacter) rapidly converts nitrite to NO3 -. Knowing the characteristics of the nitrification process and the charge of each i on, it is possible to determine the mobility of nitrogen during certain stages of the transformation. Ammonium is a positively charged ion that readily sorbs to negatively charged soil colloids, which can reduce its mobility in the soil. Nitrite and nitrate are both highly mobile forms of nitrogen. Both forms of nitrogen are negatively charged, which results in negligible interaction and sorption to soil colloids. Also, nitrite and nitrate forms dissolve quite easily in water. As a result, nitrite and nitrate are extremely susceptible to leaching by advection when adequate water is available. However, nitrate is the primary focus of most nitrogen contamination studies because the transformation of nitrite to nitrate occurs relatively quickly and nitrite is usually found in small quantities. By knowing the mobility of certain forms of nitrogen, it is possible to determine effective types of fertilizers that can be applied to crops to reduce leaching. The most common forms of nitrogen fertilizer that reduce leaching include those that contain ammonium compounds. Ammoniums adsorption to the soil colloids renders it less

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7 susceptible to leaching out of the soil (Paramasivam, 2000) and can be an acceptable form of fertilizer that can reduce total nitrogen leaching. The most common types used are ammonium nitrate, anhydrous ammonia, a nd ammonium sulfate. Bundy et al. (1986) observed significantly higher yields in potatoes when ammonium sulfate was used instead of nitrate fertilizer and concluded that the higher yields were attributed to the nitrate fertilizer leaching out of the root zone more easily than the ammonium sulfate. Extensive research has been conducted over recent years examining the chemical transport of fertilizers, specifically nitrogen fertilizers, due to concerns about water quality pertaining to nitrate-nitrogen leaching into the ground water. Leaching occurs when excess water flows through the bottom boundary of the root system. Factors that affect nitrate-nitrogen leaching on agricultural lands include soil type, organic matter content, moisture content, plant rooting depth, irrigation management, fertilizer management, etc. Of these, irrigation and nitrogen fertilizer management are perhaps the most important factors that influence nitr ate-nitrogen leaching in Floridas sandy soils. Potato Crop Management Potatoes (solanum tuberosum) grown in Florida are generally planted in spring and represent a substantial portion of the total vegetable industry in Florida. In 1996-1997, potato production in Florida represented 6.1% of the states $1.6 billion vegetable industry with 81% of the potatoes harvested during May and June following spring planting (Hochmuth and Cordasco, 2000). Th e production of most fresh vegetables usually requires large applications of nitrogen and irrigation water (Home et al., 2002). Thus, the two most important aspects of potato production are usually related to proper irrigation and nitrogen management (Waddell, 1999).

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8 Proper irrigation management is essential to achieve acceptable potato yields in areas with inadequate rainfall and soils with low water holding capacity. Even though potatoes are generally grown in areas where sandy soils are present, the plants have relatively shallow root systems (46-60 cm) because of the low root penetration strength of the plant roots. As a result, misconceptions often arise that potatoes are a high water use crop. However, there are many other crops that have equal or greater water requirements (King and Stark, 1997). In reality, potatoes are sensitive to water stress due to their complex physiological responses to moderate plant water deficits (Curwen, 1993). Ojala et al. (1990) stated that to achieve maximum productivity for potatoes, the soil must be consistently kept moist. Hochmuth et al. (2000) reported that potato plant water requirements for potatoes in Florida varied over the season increasing from 40% of the reference evapotranspiration (ETo) during initial plant growth periods to approximately 110% of ETo at peak growth and tuber development and then decreasing to 70% of ETo during the final growth period of tuber development. King and Stark (1997) showed that potatoes are particularly sensitive to water stress during tuber initiation and early tuber development. They also determined that water stress during tuber bulking has more of an effect on tuber yield than quality. Also, water stress accelerates leaf senescence and disrupts new leaf formation, which results in an unrecoverable loss of tuber bulking. Belange r et al. (2000) showed that supplemental irrigation could improve yield significantly dur ing dry years. From their trials, the average yield increase in irrigated versus nonirrigated crops was 6.5 tons/ha and 5.1 tons/ha for the total and marketable yields, respectively.

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9 Even though supplemental irrigation is essential for potato production, over irrigation can also have negative impacts on potato yield. Providing excess water at planting promotes seed piece decay, delays emergence because of decreased soil temperature, and leaches nitrate-nitrogen out of the root zone causing nitrogen deficient plants (King and Stark, 1997). Belanger et al (2000) concluded that excess water could result in negligible increases or even decreases in final yield. These findings demonstrate the importance of proper irrigation scheduling and the need for an adequate irrigation system that can apply supplemental light wa ter applications uniformly, frequently, and economically. Poor irrigation scheduling can have adverse effects on nutrient availability for potatoes, especially nitrogen. Nitrogen is usually the most limiting nutrient for potato growth, especially in sandy soil regions (Errebhi et al., 1998). The most readily available form of nitrogen that potato plants utilize is nitrate-nitrogen, which is also highly mobile in the soil. Potatoes, in general, have a high demand for nitrogen with a rather low total recovery (Zvomuya et al., 2003). The low recovery is partially due to the rather shallow root system of the plants. Potato plants can have a maximum root depth of up to 60 cm, but 90% of the roots are typically located in the upper 25 cm (Tanner et al., 1982). As a result, excess water can result in nitrate-nitrogen being leached out of the plant root zone. Nitrogen fertilizer application scheduling is critical to have adequate potato crop yield, especially in sandy soils. Nitrogen uptake by potato plants varies depending on the growth stage of the plants. Even with op timum levels of nitrogen available for plant uptake, the nitrogen recovery tends to vary considerably. Neetson (1990) found that potato plants utilized only 50% of the applied fertilizer and Unlu et al. (1999) found that

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10 only 20% was taken up by the plants. Consequently, extensive studies have been conducted on the nitrogen uptake of potato plants at different growth stages in order to determine the high demand periods during the potato plant growth cycle. Sullivan et al. (1999) found that potato plants take up the majo rity of nitrogen during vine growth of the vegetative growth stage. Also, it was determined that the total crop uptake of nitrogen was reached at approximately 100 days after pl anting during tuber growth. Osaki et al.s (1992) research suggests that nitrogen applied after flowering has little or no effect on final tuber yield. Current IFAS recommendations for Florida, state that the nitrogen application rate should be approximately 200 kg/ha with roughly 2/3 of the nitrogen fertilizer band-applied at planting or crop emergence and the remaining fertilizer applied 35 to 40 days later as side-dress (Hochmuth and Cordasco, 2000). With minimal irrigation application and proper fertilizer timing, maximum fertilizer recovery can be achieved with reduced leaching and acceptable yields can be maintained. Irrigation scheduling and fertilizer management significantly influences nitratenitrogen leaching. Errebhi et al. (1998) stated that early applications of nitrogen on sandy soils could lead to nitrate-nitrogen being leached below the root zone during heavy rainfall events and excess irrigation. Neetson et al. (1990) found that nitrogen application recommendation of potato crops in sandy soils of the Netherlands were too large, which increased the probability of nitrate-nitrogen leaching. The researchers modeled results indicated that the current Dutch nitrogen application recommendation (300 kg/ha) could be reduced by 25% and would result in a total yield decrease of only 2% for clay and loam soils. Neetson et al. (1990) also determined that the nitrogen application

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11 requirements were higher for sandy soils when compared to the requirements of loams and clays. Results from Verhagens (1997) model simulations using the WAVE model showed that the current Dutch fertilizer recommendation of 250 kg/ha of nitrogen for potatoes was too high. During the 1994 experiment, it was determined that using the current recommendation resulted in 75 kg/ha of nitrate-nitrogen being leached out of the root zone of loamy soils, which caused the ground water concentrations to exceed the pre-set standard of 50 mg-NO3/L. Verhagen (1997) further concluded that a 75 to 100kg/ha reduction in nitrogen fertilizer would result in dramatic decreases in total nitrogen leached. In spring 2001, Albert (2002) conducted a study monitoring and modeling water and nitrogen transport of a potato crop produced on a 56.7 ha field in the Middle Suwannee River Basin in OBrien, FL. Results from this study showed that nitratenitrogen leached rapidly out of the sandy soils located on the vegetable farm. Albert showed that only 30% of the 313 kg/ha of the applied nitrogen was taken up by the potato plants. Model results indicated that yields stabilized around 225-kg/ha of applied nitrogen and that irrigation could have been reduced as much as 30%, resulting in reduced leaching and acceptable yields. However, there were inconsistencies in the modeling methods used by Albert (2002). In Al berts first simulations, he found that the computer model under predicted crop yield considerably. To remedy this problem, fertilizer applications were doubled in the models input files because it was thought that the model simulations were restricted to the bed rather than the entire field area. Since the fertilizer was band-applied to the bed, it appeared that doubling the fertilizer rate

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12 applied on a field area basis was reasonable. The doubled fertilizer applications produced fairly accurate results for the 2001 crop. This methodology was subsequently called into question because the computer model actually simulates the entire area, not just the bed area as previously thought. After these findings, it was clear that further calibration and modifications of model were necessary so that it could adequately represent the potato crop system at the field scale project site. The main objectives of this research were to extend Alberts previous work of monitoring and modeling the water and nitrate transport in the vadose zone at the same research site in OBrien, FL and to modify the numerical crop model to more accurately simulate the 2001 and 2002 potato crop data. Once the model is modified and calibrated properly, it can be implemented as a tool to assist in the development of a BMP that effectively reduces nitrate-nitrogen leaching and maintains acceptable yields.

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13 CHAPTER 2 FIELD EXPERIMENTS AND METHODOLOGIES Site Description The research farm is a 2020-ha row-crop operation located in OBrien, FL that is approximately 16-km northwest of Branford. Th e soils (Penney fine sand) located in this portion of the Middle Suwannee River Basin are very sandy and susceptible to drought, so irrigation is critical in the economic viability of the farming operation. Pivot 12 was selected as the field scal e project site based on ground penetrating radar (GPR) and soil profile evaluation (Alb ert 2002). The land surface elevations at pivot 12 range from 13.7 to 15.3 meters above mean sea level (msl). Long-term piezometric head levels indicate that the average elevation of the top of the Floridan Aquifer fluctuates from 7.3 meters (annual low) to 8.5 meters (annual high) above msl. The site has a semi-continuous clay layer that varies from 0.9 to 7.6 meters below the soil surface based on the GPR analysis of the selected sites by Natural Resources Conservation Service personnel. Soil characteristics for the site including the saturated hydraulic conductivity, bulk density, porosity, field capacity, and wilting point were determined based on laboratory experiments (Sanchez, oral communication). Results from the laboratory measurements of the soil-moisture release curve (Table 2-1) indicated that the volumetric moisture content at field capacity (-345 cm) and wilting point (-15,000 cm) was approximately 67% and 2%, respectively (Albert, 2002). From the laboratory results, it was also determined that the saturated hydraulic conductivities for the 0-50 cm and 50-100 cm

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14 depths were 4,515 cm/day and 3,759 cm/day, respectively. The bulk densities for the 050 cm and 50-100 cm depths were measured to be 1.48 g/cm3 and 1.56 g/cm3. Table 2-1. Retentivity data measured at the research site. Soil Tension (cm) Volumetric Moisture Content (0-50 cm) Volumetric Moisture Content (50-100 cm) 0 4 20 30 45 60 80 100 150 200 345 15300 38.8 38.8 35.8 29.9 20.3 14.2 11.1 9.7 8.2 7.3 6.6 1.8 35.3 35.2 34.4 31.2 17.2 12.6 9.3 8.0 6.9 6.2 5.8 1.8 Field Sampling Methodologies In 1999, research began at the project site with periodic monitoring of the Upper Floridan Aquifer and the vadose zone. The aquifer monitoring consisted of biweekly shallow groundwater samples and the vadose zone monitoring included taking soil samples from the soil surface down to the clay la yer every six weeks. The data were used to observe long-term trends in the ground water nitrate-nitrogen concentrations, water table elevations, and vadose zone soil-water nitrate-nitrogen content at the research farm. These data results indicate that the leached nitrate-nitrogen from the farm may be a significant source of the increased nitrogen loads to the Suwannee River Basin (Albert, 2002). Beginning in 2001, soil samples were taken biweekly from the soil surface to a depth of 90 cm during the spring potato growing season in addition to the deep soil samples that were taken every six weeks throughout the year. The samples were taken at 10 locations in the center of the potato plant beds at depths of 0-15, 15-30, 30-60, and 60-

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15 90 cm for the 2001 and 2002 spring potato growing seasons. These soil samples were taken in close proximity to the 10 wells located on the project site. Refer to Albert (2002, pp 19) for well locations. The samples were analyzed at the Department of Soil and Water Science at the University of Florida for KCL extractable nitrate and ammonium concentrations, bulk density, and moisture content (Albert, 2002). To determine the moisture contents of the soil samples, the soil samples were weighed wet then oven dried and reweighed. Results from the analysis yielded gravimetric water content (Eq. 2-1). Volumetric water content was then calculated from the gravimetric water content (Eq. 2-2). dry dry wet gm m m (2-1) b g vol (2-2) where g is the gravimetric moisture content; vol is the volumetric moisture content; mwet is the wet weight of the soil sample; mdry is the dry weight of the over-dried sample; b is the bulk density of the soil. Appendix A shows the field measurements and detailed calculations for the spring 2001 and 2002 potato crop soil samples. The shallow soil samples were taken in order to obtain a more accurate representation of the water and nitrate movement in the upper portion of the vadose zone associated with plant roots, which affects nitrogen and water uptake. An on site weather station was set up in December 2000 approximately -km from the project site to record hourly rainfall, solar radiation, and temperature. Weather station instruments included a Texas Electronics TR525 rain gauge, a Campbell scientific thermometer, and a LiCor LI200X pyranometer that were attached to a CR-10X data logger.

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16 During the 2001 and 2002 potato crops, plant biomass sample sets were taken based on the sampling methodologies outlined in the DSSAT Users Manual (Tsuji et al., 1999). The biomass sample dates specified by Tsuji et al.. are based on critical growth stages of the potato crop development including tuber initiation, 20 days after tuber initiation, and 40 days after tuber initiation. Each biomass harvest consisted of eight individual samples of average size with two samples taken in each quadrant. In 2001, the plant samples were taken on a per plant basis, while in 2002 the samples were collected on a per area basis. The analysis of the plant samples included dry/wet weight measurements of leaves, stems, and tubers, measurement of the leaf area index (LAI), and nitrogen content measurements of the leaves, stems, and tubers. The plants were separated into leaves, stems, and tubers, then weighed wet. Plant roots were not examined as recommended by Dr. K.J. Boote (2001, oral communication), because of the negligible amounts of nitrogen in roots (Albert, 2002). The samples were then dried at 75 C in an oven until a constant weight was reached and reweighed. The dried samples were sent to the Analytical Research Laboratory at the University of Florida and analyzed for total kjeldhal nitrogen (TKN). Results from the analysis and calculations are shown in Appendix B. In addition to the biomass harvests, a final harvest was conducted at the end of 2001 and 2002 growing seasons to determine final yield. In 2001, twenty, 9.1 m long sections of row, 10 on each half of the field, were harvested by manually digging up all the potatoes. At the end of the 2002 growing season, twelve, 7.6 m long sections of row, three in each quadrant, were harvested manually by digging up the potatoes. The

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17 harvested potatoes were then divided up into three grades based on size, weight, and quality to determine final tuber yield. Field Results The following is a detailed discussion related to the field methods and results of the spring 2001 and 2002 potato crops. The vadose zone and crops were monitored closely throughout each crop season in order to accurately estimate the amount of nitrogen entering the underlying Floridan Aquifer and to determine the nitrogen recovered by the potato crops. Two different management practices were used on the north and south halves of the field for the spring 2001 potato crop. Both management practices were similar except for a slight reduction in fertilizer application amount applied to the south half of the field. The north and south halves of the field r eceived 313 and 280 kg/ha of nitrogen fertilizer, respectively. The irrigation schedule was the same for both halves of the field. As a result, only the north half results for the 2001 crop are presented in this section. The spring 2002 potato crop has similar planting details as those of the 2001 crop. Two management practices were used on the north and south halves of the field in 2002. The north half of the field received 292 kg/ha of nitrogen fertilizer with the farmers typical irrigation management. The south half of the field received 261 kg/ha of nitrogen fertilizer with a 21% reduction in applied irri gation. The data collection during the spring 2001 and 2002 potato crops were focused on accurately quantifying the movement of nitrogen for the different management practices implemented at the site.

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18 Spring 2001 Potato Crop Planting details, crop management, and weather Essential information including planting geometry, fertilization scheduling, cultivar type, etc. for the north and south halves of the field were obtained from the farmer and are shown in Table 2-2 and 2-3. Irrigation amounts were determined from the irrigation records kept by the farmer and can be found in Appendix C in the SUBSTOR input files under irrigation. The farmers irrigation strategy was to maintain the soil moisture at field capacity in order to meet the crops water requirement during the growing season. Table 2-2. Spring 2001 potato crop planti ng information obtained from farmer. Cultivar Red LaSoda Previous Crop Cotton Planting Depth 15.2 cm Row Spacing 101 cm Planting Density* 27,110 plants/ha Seed Weight 99.2 grams *The actual growing density assumes that only 90% emergence of planting density (24,387 plants/ha). Table 2-3. Spring 2001 approximate nitrogen fertilizer schedule and amounts. Applied Nitrogen (kg/ha) Date Julian Day North Half Nitrogen Applied South Half Nitrogen Applied Fertilizer Type/Application Method 01/18/2001 18 38.2 29.2 34-0-0 pre-plant, in bed 02/15/2001 46 16.8 16.8 10-34-0 starter, at plant 03/05/2001 64 112.3 105.5 18-0-0-3 sidedress, liquid 03/25/2001 84 112.3 94.3 18-0-0-3 sidedress, liquid 04/28/2001 118 33.7 33.7 30-0-0, fertigation As previously stated, weather data were collected from an onsite weather station that included hourly solar radiation, rainfall, and temperature. The data were downloaded from the CR-10X periodically.

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19 Moisture content results As previously discussed, the vadose zone monitoring consisted of measurements of the moisture contents and soil-water nitrogen concentrations over consecutive depths and times. The soil sampling was comprised of biweekly samplings at depths of 0-15 cm, 1530 cm, 30-60 cm, and 60-90 cm. In 2001, soil samples consisted of 10 soil sample sets taken in the center of the row at different locations. The results for the average volumetric moisture content of the soils over the growing season are shown in Figure 2-1. 0 2 4 6 8 10 12 14 03/01/0103/11/0103/21/0103/31/0104/10/0104/20/0104/30/0105/10/01 DateVolumetric Moisture Content (%) 0 2 4 6 8 10 12 14 3/1/013/11/013/21/013/31/014/10/014/20/014/30/015/10/01Total Water Applied (cm) Total Water Applied (cm) 015 cm 15-30 cm 30-60 cm 60-90 cm Figure 2-1. North half average moisture contents for the spring 2001 potato crop. Total water includes rainfall plus irrigation. The results indicate the entire soil profile tended to remain at or above field capacity throughout the season. Note that only small fluctuations (Table 2-4) were observed in the measured moisture contents, due to the frequency that the soil samples were taken and the well-drained characteristics of the soils located at the project site. Also, note the moisture contents are above the field capacity of 6% determined in the

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20 laboratory at cm soil matric potential, which indicates that field capacity (or gravity drained water content) may occur at slightly lower (less negative) tensions than cm. Table 2-4. Statistical analysis of 2001 north half soil samples moisture content results. Date Depth (cm) Average (%) Maximum (%) Minimum (%) Standard Deviation (%) 03/02/01 0-15 15-30 30-60 60-90 8.94 10.82 8.43 10.52 10.82 19.58 9.10 15.95 7.71 7.71 6.79 7.98 1.20 4.94 1.10 3.67 03/06/01 0-15 15-30 30-60 60-90 6.92 9.08 9.07 9.48 7.54 9.38 10.62 11.08 6.38 8.71 7.42 8.39 0.52 0.32 1.15 1.04 03/24/01 0-15 15-30 30-60 60-90 8.95 9.18 9.32 9.25 11.36 9.90 10.29 10.10 7.30 7.77 8.26 8.09 1.53 0.85 0.79 0.78 04/03/01 0-15 15-30 30-60 60-90 7.25 8.13 9.14 9.71 9.12 9.08 10.53 14.09 6.08 6.74 8.42 7.69 1.25 0.86 0.82 2.63 04/20/01 0-15 15-30 30-60 60-90 10.51 9.73 9.41 8.66 12.54 10.81 10.45 9.01 7.82 8.00 8.25 7.78 1.89 1.05 0.80 0.51 05/04/01 0-15 15-30 30-60 60-90 7.33 12.13 8.75 8.32 12.17 32.75 9.49 9.23 4.57 5.42 7.81 7.21 3.07 11.58 0.68 0.74 The relatively high average value shown on 05/04/2001 for the 15-30 cm depth implies that there may have been various sources error during the analysis of the sample set. The standard deviation for the 15-30 cm depth was 11.6% (Table 2-4) with maximum and minimum values of the moisture content measuring to be 32.8% and 5.4%,

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21 respectively. This indicates that the samples may have either been compromised in storage or that there may have been errors in the moisture content measurements. In any case, it is obvious that the soils tend to drain to field capacity relatively quickly even when substantial amounts of water are applied to the crop. For example, from 4/1/2001 to the end of the crop season, the field received approximately 1.0 cm of applied water daily. This applied water had very little impact on moisture content. The fact that field capacity was maintained throughout the season, even after large water applications, provides evidence that the potato crop was over-i rrigated. Also, the drainage features of the soils on the site show that there is little impedance of the downward movement of the soil-water in the soil profile, which has a large influence on nutrient leaching. Nitrate-nitrogen results Figure 2-2 depicts the temporal and spatial nitrate-nitrogen mass transport in the bed. The figure is a good illustration of how the nitrate-nitrogen moves through the soil profile and into the Floridan Aquifer. It should be noted that plant roots extend to a maximum root depth of approximately 30-45 cm, which makes it improbable that any nutrients are removed from the soil by plants below this depth. Therefore, nutrients below this depth will eventually enter the underlying Floridan Aquifer. Also it should be noted that fertilizer application rates were reported on a total field area basis when the applied nitrogen was actually concentrated in the bed. As a result, the values shown and discussed for nitrate-nitrogen loads in Figure 2-2 represent the bed area only, and the reported fertilizer application rates are for the entire field area. After the pre-plant and starter nitrogen fertilizer applications on January 18, 2001 and February 16, 2001, respectively, there was minimal leaching because there was no water applied. After March 2, 2001, steady nitrate-nitrogen leaching occurred as a result

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22 of the 1.7 cm rainfall event on March 4, 2001 (see the results for the soil samples taken on March 6, 2001). Information provided by the grower indicated there was nitrogen fertilizer applied on March 5, 2001. However, the data indicate that this information may be inaccurate and fertilizer was actually applied after March 6, 2001. If the fertilizer was really applied on March 5, 2001, there should have been an increase in the nitratenitrogen content in the soil, but none was found from the soil samples taken on March 6, 2001. Albert (2002) observed that reported and actual fertilization dates had discrepancies. For example, Albert (2002) stated that it was reported that a fertilizer application occurred on March 25, 2001 when it was actually observed being applied the day before. 0 50 100 150 200 250 300 350 400 03/02/0103/06/0103/24/0104/03/0104/20/0105/04/0105/25/0106/06/01 DateNitrate-Nitrogen (kg/ha) 60-90 cm 30-60 cm 15-30 cm 0-15 cm N-Applied: 38 kg/ha (1/18/01) 17 kg/ha (2/16/01) H2O Applied: 1.7 cm N-Applied: 112 kg/ha (3/5/01) H2O Applied: 11 cm N-Applied: 112 kg/ha (3/24/01) H2O Applied: 7.6 cm N-Applied: 0 H2O Applied: 16.3 cm N-Applied: 0 H2O Applied: 13.2 cm N-Applied 34 kg/ha (4/28/01) H2O Applied: 14.8 cm N-Applied: 0 H2O Applied: 1.2 cm N-Applied: 0 Figure 2-2. Average 2001 north half nitrate-nitrogen content in top 90 cm of the bed area. Each depth increment is an average of five samples. The applied nitrogen is the total nitrogen applied for the total area. All fertilizer application dates are approximate. After March 6, 2001, the majority of the 112 kg/ha of nitrogen fertilizer leached out of the soil profile because there was a considerable amount of rainfall received by the

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23 field. Another nitrogen fertilizer appli cation of 112 kg/ha, applied on March 24, 2001, resulted in the total nitrate-nitrogen content in the soil increasing to approximately 335 kg/ha in the top 90 cm on March 24, 2001. After March 24, 2001, the nitrate-nitrogen content remained relatively constant through April 3, 2001 with a slight decrease due to the 7.6 cm of applied water and root uptake. The decrease in total nitrate-nitrogen content was small, likely because the plant canopy had started to reach the maximum leaf area index (LAI), which reduced the total e ffective rainfall. The decreased effective rainfall in decreased infiltration and nitrate-nitrogen leaching. However, during the period from March 24, 2001 to April 3, 2001, there was still considerable nitrate-nitrogen movement in the soil profile. In fact, 32.8 kg/ha of nitrate-nitrogen was leached out of the top 30 cm and into the lower 60 cm with the majority of the leached nitrate-nitrogen residing at the 60-90 cm depth out of the reach of plant roots. Starting April 1, 2001, the field was conti nuously irrigated applying approximately 0.8 cm of water daily. During this period, nitrate-nitrogen was leached out of the soil rapidly as seen from the soil samples taken on April 20, 2001. Between April 3, 2001 and April 24, 2001, there was a net reduction in nitrate-nitrogen in the soil of 281 kg/ha. As a result, an additional 34 kg/ha of nitrogen fertilizer was applied on April 28, 2001. With the continuous irrigation, the nitrate-nitrogen applied to the field on April 28, 2001 was leached out of the soil profile reducing the total nitrate-nitrogen to 83.2 kg/ha on May 25, 2001. On May 20, 2001, the center pivot was shutdown, herbicides were applied to the crop to kill the vegetation, and there were no additional nitrogen fertilizer applications. This would create an environment in which there would be minimal leaching and no nutrient uptake by the plants. However, there was a substantial increase

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24 in total nitrogen content after May 25, 2001 that can be seen from the data for June 6, 2001. There are a few possibilities that may have contributed to the increased nitrogen content in the soil. One possibility is that there was an upward flux of soil-water and nitrate-nitrogen due to the evaporation occurring at the soil surface. But the soils located at the project site are extremely sandy and are probably self-mulching, which makes it unlikely that there was upward flux of water and nitrogen. The most probable explanation is related to the re-bedding of the beds on June 4, 2001 before harvest to prevent potato decay. During this procedure, the dead plant material was incorporated into the soil, which could have been mineralized by the soil microorganisms. Crop monitoring results Crop monitoring of the spring 2001 potato crop included obtaining information from the farmer, visual field observations of timing of particular phenological events, and crop biomass sampling during the growing season. The crop development was well documented from weekly field visits to the farm over the growing season and information including planting date, emergence, tuber initiation, maximum LAI, and killed date were noted (Table 2-5). Table 2-5. Important dates related to planting, harvest, and phenological events (2001). Event Date Days After Planting Planting 02/15/2001 0 Emergence 03/07/2001 20 Tuber Initiation 04/01/2001 45 Anthesis 04/04/2001 49 Maximum LAI 04/20/2001 64 Killed Date 05/21/2001 95 Harvest 06/01/2001 106 The biomass samples were taken 37, 40, 47 and 78 days after planting. Total final yields based on all the potatoes harvested was 38.7 Mg/ha for the north half and 33.7

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25 Mg/ha for the south half. The biomass samples and the final yield were used to estimate total nitrogen uptake of the potato crop. The n itrogen concentrations determined from the plant tissue analysis were multiplied by each pl ant part and then summed to determine the total nitrogen mass in each plant sample. The average plant nitrogen mass per plant was then determined for each sample date and multiplied by the planting density of the entire field area to determine the nitrogen uptake per unit area. At the time of the final yield harvest, the vegetative growth had been killed by herbicides, so it was not possible to measure the final nitrogen uptake. Thus, the final nitrogen uptake was extrapolated using the plant data collected on May 4, 2001 and June 1, 2001. Leaf and stem weight at the kill date on May 21, 2001 were assumed to be the same as those on May 4, 2001. Also, the nitrogen concentrations of stems, leaves, and tuber were assumed to be the same as those measured from the May 4, 2001 plant samples. The tuber weight measured on June 1, 2001 was used as an estimate of the tuber weight on May 21, 2001. Figure 2-3 compares the total nitrogen uptake to the cumulative nitrogen applied on the north half of the field. The cumulative nitrogen includes the fertilizer applications plus the nitrogen that was applied through irrigation due to increased nitrate concentrations (20 mg/L) in the irrigation well water. Figure 2-3 indicates that approximately 101.7 kg/ha of the nitrogen applied was actually recovered by the plants. The field experiments that were conducted provide valuable knowledge related to nitrogen uptake and leaching for potato crops. Soil samples indicated that the irrigation applied to the field was more than adequate to maintain field capacity. Also, soil-water nitrate concentrations show that nitrate-nitrogen tends to move through the soil profile quickly and out of the zone that plant roots take up

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26 the nitrogen effectively due to the over irrigation of the crop. This was substantiated from the four biomass harvest taken over the growing season, which indicate that approximately 30% of the total nitrogen applied was utilized by the crop. 0 50 100 150 200 250 300 350 400 450 1/1/011/15/011/29/012/12/012/26/013/ 12/013/26/014/9/014/23/015/7/015/21/01 DateNitrogen (kg/ha) N-Applied Plant Uptake Figure 2-3. North half cumulative nitrogen applied and total crop uptake (2001). Error bars represent one standard deviation about the mean of the measured values. No standard deviation was calculated for the final point because point was extrapolated. Also, error bars are present on the all other samples but cannot be seen due to the small standard deviations relative to the measured values. Spring 2002 Potato Crop Planting details, crop management and weather The spring 2002 potato crop had similar planting details to those of the spring 2001 potato crop. All the planting information listed in Table 2-2 for the 2001 potato crop are the same for the 2002 potato crop, except that corn was the previous crop planted and row spacing was 90 cm. As previously state d, two different management practices were

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27 implemented on the field. The south half received approximately a 21% reduction in irrigation from that used on the north half and a 12% reduction in nitrogen applied (Table 2-6). The south half irrigation was managed according to weather conditions and crop status, which was monitored daily by Justin Jones from the University of Florida Research Center located in Live Oak, FL and Joel Love, a FDACS employee. The irrigation schedules for the north and south halves of the field are shown in Appendix C. Weather data were collected weekly from an onsite weather station adjacent to the field, which include hourly solar radiation, rainfall, and temperature. Table 2-6. Spring 2002 approximate nitrogen fertilizer schedule and amounts. Date Julian Day Applied Nitrogen (kg/ha) Fertilizer Type/Application Method North 1/10/2002 10 41 4-10-27, pre-plant in bed 1/15/2002 15 28.5 19-0-0, pre-plant in bed 2/13/2002 44 17 10-34-0, at plant 3/13/2002 72 101.5 19-0-0, sidedress 3/25/2002 84 104 19-0-0, sidedress South 1/16/2002 16 90.5 19-0-0, in-bed 2/16/2002 47 17 10-34-0, at plant 3/15/2002 74 56 19-0-0, sidedress 3/26/2002 85 97.5 19-0-0, sidedress North half moisture content results The methods used to monitor vadose zone for the spring 2002 potato crop were similar to methods discussed previously for the spring 2001 potato crop with a few modifications in the field methods. Soil samples were taken on a biweekly basis at 10 locations in close proximity to the wells, alternating between the north and south halves of the field each week. The 10 biweekly sample sets were comprised of five sets of

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28 samples taken in the center of the beds and five taken in the center of the furrow. The additional furrow samples were taken in order to observe the lateral movement of nitrogen and water between the bed and furrow. The samples were taken at the same depth increments, 0-15, 15-30, 30-60, and 60-90 cm, as the 2001 soil samples. The complete set of field measurements and results for spring 2002 potato crop soil samples are shown in Appendix A. The results for the north half average volumetric moisture contents of the bed soil samples are shown in Figure 2-4. Refer Table 2-7 for the standard deviations of the measured values. 0 2 4 6 8 10 12 14 16 01/01/0201/21/0202/10/0203/02/02 03/22/0204/11/0205/01/0205/21/02 DateVolumetric Moisture Content (%) 0 5 10 15 20 25 30 1/1/021/21/022/10/023/2/023/22/024/11/025/1/025/21/02Total Water Applied (cm) Total Water Applied (cm) 015 cm 15-30 cm 30-60 cm 60-90 cm Figure 2-4. North half average volumetric moisture contents for the spring 2002 potato crop in the center of bed. Total water includes rainfall plus irrigation. The results shown in Figure 2-4 for the north half moisture contents provide a good illustration of how the soil tended to remain at or above field capacity in the bed over the growing season. Even with excessive amounts of water applied to the field, the soils generally drained to field capacity rapidly. Significant increases in moisture content are apparent only in instances when the soil samples were taken directly following a large rainfall event. This is shown in the January 23, 2002, March 7, 2002 and April 17, 2002

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29 soil moisture content results. On January 23, 2002, the moisture content increase is due to the 4.7 cm of rainfall that occurred on January 21, 2002. The increase in the moisture contents for the samples taken on March 7, 2002 are a direct result of the 6.9 cm and 6.4 cm of rainfall that occurred on March 3, 2002 and March 4, 2002, respectively. The last noticeable increase in the moisture contents on April 17, 2002 was caused by the 3.7 cm of rainfall on April 16, 2002. The soil drained considerably after May 5, 2002, because there was little rainfall and irrigation was minimal. On May 11, 2002, the pivot was shut down, so no supplemental water was applied to the field. Thus, this was the cause of the low moisture contents from the May 15, 2002 soil samples. Table 2-7. The standard deviations of the 2002 north half measured volumetric moisture contents. Standard Deviation (%) Depth Date 0-15 cm 15-30 cm 30-60 cm 60-90 cm 01/09/02 0.60 0.25 0.51 0.49 01/23/02 0.32 0.96 1.62 0.46 01/30/02 0.59 0.86 0.91 0.65 02/21/02 1.28 0.39 0.58 0.72 03/07/02 0.58 0.46 0.79 0.38 03/20/02 0.26 0.63 0.45 0.49 04/03/02 0.39 0.91 0.98 0.83 04/17/02 0.92 0.46 0.81 0.92 05/01/02 1.22 0.81 0.80 0.68 05/15/02 1.02 0.84 1.06 0.78 05/29/02 1.99 1.18 0.42 0.56 South half moisture content results Figure 2-5 shows the results for the south half average volumetric moisture contents for the bed soil samples. The standard deviations of the measured values for the south half moisture contents are contained in Table 2-8.

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30 0 2 4 6 8 10 12 14 16 01/01/0201/21/0202/10/0203/02/0203/22/0204/11/0205/01/0205/21/02 DateVolumetric Moisture Content (%) 0 5 10 15 20 25 30 1/1/021/21/022/10/023/2/023/22/024/11/025/1/025/21/02Total Water Applied (cm) Total Water Applied (cm) 015 cm 15-30 cm 30-60 cm 60-90 cm Figure 2-5. South half average volumetric moisture contents for the spring 2002 potato crop in the center of bed. Total water applied includes rainfall and irrigation. The results from the experiment conducted on the south half of the field gives valuable insight on how plant water availability was affected by the reduction in the irrigation applied. During the experiment, there were a few noticeable increases in the moisture content of the soil. The first two sets of the average moisture content results shown in Figure 2-5 are identical to those shown in Figure 2-4. The field was still undergoing preparation for the crop at this time and the plant beds had not been made yet. So, the cause of the increase in moisture content that was observed from the January 23, 2002 samples are the same as those previously discussed. The high moisture contents measured from the April 12, 2002 soil samples were caused by 0.1 cm of rainfall occurring the day of sampling and by prior rainfall events of 1.9 cm on April 10, 2002 and 2.1 cm on April 11, 2002. Besides the soil sample sets collected directly following a large rainfall event, the majority of the moisture content measurements of the soil samples generally remained at or slightly above field capacity. The moisture content

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31 results indicate the reduced irrigation applied had very little impact on plant water availability and shows that the north half of the field was over-irrigated. Table 2-8. The standard deviations of the 2002 south half measured moisture contents. Standard Deviation (%) Depth Date 0-15 cm 15-30 cm 30-60 cm 60-90 cm 01/09/02 0.66 0.26 0.32 0.57 01/23/02 1.73 0.81 0.68 0.77 02/06/02 0.45 0.96 0.42 0.27 02/27/02 0.78 0.99 1.79 1.30 03/15/02 0.46 0.76 0.57 0.47 03/27/02 1.10 0.41 0.96 0.57 04/12/02 0.13 0.05 2.50 1.75 04/24/02 1.06 0.73 0.58 0.40 05/06/02 1.22 1.91 0.75 0.85 05/22/02 2.68 1.20 1.24 0.95 01/09/02 0.66 0.26 0.32 0.57 North half bed nitrate-nitrogen results The results from the soil samples taken in the beds also provided information pertaining to the nitrate-nitrogen transport in the soil profile. The bed soil sample results for the north half of the field are shown in Figure 2-6. The figure shows the nitratenitrogen movement in the soil over time and the possibility of the nitrogen leaching into the underlying Floridan Aquifer on the north half of the field. Remember, the plant roots occupy only the top 30-45 cm and are restricted to the bed only, so any nitrate-nitrogen below this depth eventually enters the aqui fer. At the beginning of the spring 2002 potato crop season, two pre-plant nitrogen fertilizer applications of 41 kg/ha and 28.5 kg/ha were applied to the north half of the field on January 10, 2002 and January 15, 2002, respectively. After the fertilizer applications, there was a noticeable increase in the nitrate-nitrogen content that is shown in the results from the soil samples taken on January 23, 2002. The majority of the applied nitrogen had already leached to the 15-30

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32 cm depth in the soil profile due to the 11.8 cm of rainfall that occurred between January 9, 2002 and January 23, 2002. 0 50 100 150 200 250 300 350 400 450 500 01/09/0201/23/0201/30/0202/21/0203/07/0203/20/0204/03/0204/17/0205/01/0205/15/0205/29/0206/12/02 DateNitrate-Nitrogen (kg/ha) 60-90 cm 30-60 cm 15-30 cm 0-15 cm N-Applied: 41 kg/ha (01/10/02) 28.5 kg/ha (01/15/02) H2O Applied: 11.8 cm N-Applied: 0 H2O Applied: 2.9 cm N-Applied: 17 kg/ha (02/13/02) H2O Applied: 1.2 cm N-Applied: 0 H2O Applied: 14.8 cm N-Applied: 101.5 kg/ha (03/13/02) H2O Applied: 3.3 cm N-Applied: 104 kg/ha (03/25/02) H2O Applied: 10.8 cm N-Applied: 0 H2O Applied: 15.4 cm N-Applied: 0 H2O Applied: 10.8 cm N-Applied: 0 H2O Applied: 4.2 cm N-Applied: 0 H2O Applied: 1.9 cm N-Applied: 0 H2O Applied: 5.8 cm Figure 2-6. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center of bed. Each depth increment is an average of five samples. The applied nitrogen is the total nitrogen applied for the total area. All fertilizer application dates are approximate. After January 23, 2002, the nitrate-nitrogen continued to be leached out of the soil profile, which decreased the amount of nitrate-nitrogen in the top 30 cm. This is shown in the January 30, 2002 soil sample results. There was a slight increase in the total average nitrate-nitrogen content at 30-90 cm, but the majority of the nitrate-nitrogen had already leached out of the soil profile by this time. Another nitrogen fertilizer application of 17 kg/ha was applied on February 13, 2002 and the soil samples taken on February 21, 2002 display an 11.5 kg/ha increase in the nitrate-nitrogen content at 0-15 cm. However, considerable leaching still occurred over this period. The nitrate-nitrogen that was observed at the 30-60 cm depth on January 30, 2002 had leached out of the soil profile by

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33 February 21, 2002. The north half of the fiel d had received large amounts of total applied water between February 21, 2002 and March 7, 2002, which reduced the average total nitrogen content to 43.9 kg/ha by March 7, 2003. On March 13, 2002, 101.5 kg/ha of nitrogen fertilizer was applied to the field, which was around the time of crop emergence. The fertilizer increased the nitratenitrogen amount at 0-15 cm to approximately 119 kg/ha, which is shown in the results from the soil samples taken on March 20, 2002. Small increases in the nitrate-nitrogen content were observed at lower depths due to the leaching from the upper 0-15 cm that occurred from the 3.3 cm of total water received. After March 20, 2002, the majority of the nitrate-nitrogen in the soil leached out of the top 90 cm. This was evident after examining the results for the soil samples taken on April 3, 2002. Between March 20, 2002 and April 4, 2002, there was an additional nitrogen fertilizer application on March 25, 2003. The fertilizer application had little affect on the total average nitrate-nitrogen content in the top 90 cm of the soil profile according to the April 4, 2002 soil results. Approximately 25% of the nitrogen that was located in the top 30 cm on March 20, 2002 was taken up by the potato plants by April 4, 2002 (Figure 2-10), which left the majority of the nitrate-nitrogen to be leached out of the soil profile by the 3.1 cm of irrigation applied from March 20, 2002 through March 24, 2002. The nitrate-nitrogen then increased on March 25, 2002 as a result of the 104 kg/ha of nitrogen fertilizer applied on that day, which explains why the total average nitrate contents for March 20, 2002 and April 4, 2002 are virtually the same. Leaching occurred over the next 10 days following the fertilizer application, which is shown in the April 17, 2002 soil sample results. The majority of the applied fertilizer was leached out of the top 15 cm and into the lower 60

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34 cm of the soil profile. However, the majority of the nitrate-nitrogen remained in the top 90 cm of the soil because the crop canopy was starting to develop, which reduced the infiltration. There were no additional fertilizer applications after March 25, 2002. However, the May 1, 2002 results show that there was a dramatic increase in nitrate-nitrogen content, which exceeded all previous measurements. The data from the soil samples taken on May 1, 2002 have significant variations in the measured values for each depth increment, especially for the samples taken in close proximity to observation wells 9 and 10 (Table 2-9), which were the cause for the anomaly. Table 2-9. Nitrate-nitrogen content results for north soil samples taken on May 1, 2002 for wells. Well Depth (cm) Average (kg/ha) 8 0-15 15-30 30-60 60-90 8.67 8.25 10.27 15.10 9 0-15 15-30 30-60 60-90 42.87 215.06 361.32 206.52 10 0-15 15-30 30-60 60-90 39.50 450.35 45.47 270.50 11 0-15 15-30 30-60 60-90 10.63 85.89 69.24 45.69 3 0-15 15-30 30-60 60-90 5.40 107.86 45.87 99.11 The center pivot was shutdown on May 13, 2002 and the plants were killed with herbicide on May 17, 2002. Following May 1, 2002, the nitrate-nitrogen content decreased due to leaching. As in 2001, there are some noticeable increases in the nitratenitrogen content in the top 15 cm of the soil profile that were observed from the May 29,

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35 2002 and June 12, 2002 samples. The increased nitrate-nitrogen contents were most likely caused by the mineralization of the dead plant material that was incorporated into the soil at re-bedding. South half bed nitrate-nitrogen results The bed soil sample results for the south half of the field are shown in Figure 2-7. 0 50 100 150 200 250 300 350 400 450 500 01/09/0201/23/0202/06/0202/27/0203/15/0203/27/ 0204/12/0204/24/0205/06/0205/22/0206/05/02 DateNitrate-Nitrogen (kg/ha) 60-90 cm 30-60 cm 15-30 cm 0-15 cm N-Applied: 90.5 kg/ha (01/16/02) H2O Applied: 11.8 cm N-Applied: 0 H2O Applied: 3.0 cm N-Applied: 17 kg/ha (02/16/02) H2O Applied: 2.0 cm N-Applied: 0 H2O Applied: 15.6 cm N-Applied: 56 kg/ha (03/15/02) 97.5 kg/ha (03/26/02) H2O Applied: 4.1 cm N-Applied: 0 H2O Applied: 12.1 cm N-Applied: 0 H2O Applied: 9.9 cm N-Applied: 0 H2O Applied: 7.8 cm N-Applied: 0 H2O Applied: 3.1 cm N-Applied: 0 H2O Applied: 1.2 cm Figure 2-7. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center of bed. Each depth increment is an average of five samples. The applied nitrogen is the total nitrogen applied for the total area. All fertilizer application dates are approximate. The bed soil samples results provide evidence that the reduced nitrogen fertilizer and irrigation applied to the south half of the field reduced the rate and quantity of nitrate-nitrogen leached out of the vadose zone (Figure 2-7). In the beginning of spring 2002, 90.5 kg/ha of pre-plant nitrogen fertilizer wa s applied to the south half of the potato

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36 field. The applied fertilizer resulted in an increase in nitrate-nitrogen in the top 30 cm of the soil profile, which can be seen from the January 23, 2002 soil sample results. After January 23, 2002, the south half of the field received 3 cm of water, which leached approximately half of the nitrate-nitr ogen out of the top 30 cm of the soil profile. Some of the leached nitrate-nitrogen was reta ined in the bottom 60 cm, but approximately 40 kg/ha was leached of the soil profile. A slight increase in total average nitratenitrogen content on February 27, 2002 was observed, which was caused by the 17 kg/ha of nitrogen fertilizer applied on February 16, 2002. The subsequent soil samples taken on March 15, 2002 indicated that there was a substantial amount of nitrate-nitrogen leached out of the soil profile, which can be attributed to the 14.2 cm of rainfall and 1.4 cm of irrigation applied from February 27, 2002 through March 15, 2002. It appeared that there was no significant leaching of nitrate-nitrogen from 0-15 cm depth according to the soil samples results taken on March 15, 2002, but the sustained nitrate-nitrogen concentration can be attributed to the 56 kg/ha of nitrogen fertilizer applied on that day. A large increase in nitrate-nitrogen content was noticed on March 27, 2002 for the top 30 cm, which was a result the 97.5 kg/ha of nitrogen fertilizer applied the day before. The results obtained on April 12, 2002 indicated that the 6.3 cm of rainfall and 9.9 cm of irrigation applied between March 27, 2002 and April 12, 2002 reduced the nitratenitrogen content in the top 15 cm to 26 kg/ha. Most of the nitrate-nitrogen lost from the top 15 cm was retained in the 15-30 cm depth of the soil profile. The amount leached was not as dramatic as that seen on March 15, 2002, because the crop had begun to develop good canopy cover. As previously discussed, the plant canopy reduced the effective water applied to the beds, which reduced the infiltration and nitrate-nitrogen

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37 leached. An additional 9.9 cm of water was applied to the south half of the field from April 12, 2002 through April 4, 2002. This resulted in approximately half of the nitratenitrogen in the top 30 cm being leached into the bottom 60 cm of the soil profile. Senescence started to occur after April 24, 2002, which led to the large majority of the nitrate-nitrogen being leached out of the soil profile by the 7.8 cm of water applied between April 24, 2002 and May 6, 2002. The center pivot was shutdown on May 13, 2002 and the potato crop was killed by herbicides on May 18, 2002. There were noticeable increases in nitrate-nitrogen content in the top 30 cm observed from the soil samples taken on May 22, 2002 and June 6, 2002, which were most likely caused by mineralization of dead plant material incorporated in the bed at re-bedding. North half furrow nitrate-nitrogen results Originally, it was assumed that the nitrogen transport in the soil was onedimensional with the transport of the nitrogen fertilizer being restricted to the bed, because the fertilizer was band-applied to the crop. However, no data had been taken in the furrow prior to this experiment to substantiate this hypothesis. The results from the samples taken in the furrows for the north half are shown in Figure 2-8. Note that nitratenitrogen content results for the furrow soil samples are an order of magnitude smaller than that measured for the bed samples. As shown Figure 2-8, the nitrate-nitrogen content in the furrow tends to remain stable throughout the growing season. The only source of the nitrate-nitrogen in the furrows was from the irrigation water due to the elevated nitrate-nitrogen concentrations in the irrigation well water. Most of the measured values tended to range between 5 kg/ha to about 16 kg/ha for the both the north and south halves of the field with no noticeable increases in nitrate-nitrogen content following fertilizer applications. For

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38 example, on March 13, 2002 there was a side-dressed nitrogen fertilizer application of 101.5 kg/ha on the north half of the field and the results from the March 20, 2002 furrow soil samples for the soil nitrate-nitrogen content showed that the nitrate-nitrogen content in the furrow remained at about 15 kg/ha. However, there are some noticeable increases in average nitrate-nitrogen content for the nor th half of the field observed on February 21, 2002, May 1, 2002, and May 29, 2002. 0 5 10 15 20 25 30 35 40 01/30/0202/21/0203/07/0203/20/0204/03/0204/17/0205/01/0205/15/0205/29/02 DateNitrate-Nitrogen (kg/ha) 60-90 cm 30-60 cm 15-30 cm 0-15 cm N-Applied: 17 kg/ha (02/13/02) H2O Applied: 1.2 cm N-Applied: 0 H2O Applied: 14.8 cm N-Applied: 101.5 kg/ha (03/13/02) H2O Applied: 3.3 cm N-Applied: 104 kg/ha (03/25/02) H2O Applied: 10.8 cm N-Applied: 0 H2O Applied: 15.4 cm N-Applied: 0 H2O Applied: 10.8 cm N-Applied: 0 H2O Applied: 4.2 cm N-Applied: 0 H2O Applied: 1.9 cm Figure 2-8. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center of furrow. Each depth increment is an average of five samples. The applied nitrogen is the total nitrogen applied for the total area. All fertilizer application dates are approximate. South half furrow nitrate-nitrogen results Similar discrepancies were observed in the furrow soil samples taken on the south half of the field (Figure 2-9) on February 27, 2002 and June 5, 2002. But for the majority of the results, there were no noticeable increases in nitrate-nitrogen content over the growing season or following fertilizer applicati ons. The south half of the field received

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39 two side-dressed nitrogen fertilizer applications on March 15, 2002 and March 26, 2002 of 56 kg/ha and 97.5 kg/ha, respectively. Results from the south half furrow soil samples taken on March 27, 2002 showed that there was little change in the nitrate-nitrogen content in the soil. 0 5 10 15 20 25 30 02/06/0202/27/0203/15/0203/27/0204/12/0204/24/0205/06/0205/22/0206/05/02 DateNitrate-Nitrogen (kg/ha) 60-90 cm 30-60 cm 15-30 cm 0-15 cm N-Applied: 17 kg/ha (02/16/02) H2O Applied: 2.0 cm N-Applied: 0 H2O Applied: 15.6 cm N-Applied: 56 kg/ha (03/15/02) 97.5 kg/ha (03/26/02) H2O Applied: 4.1 cm N-Applied: 0 H2O Applied: 12.1 cm N-Applied: 0 H2O Applied: 9.9 cm N-Applied: 0 H2O Applied: 7.8 cm N-Applied: 0 H2O Applied: 3.1 cm N-Applied: 0 H2O Applied: 1.2 cm Figure 2-9. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center of furrow. Each of the depth increments is an average of five samples. The applied nitrogen is the total nitrogen applied for the total area. All fertilizer application dates are approximate. The results shown in Figures 2-8 and 2-9 show that the nitrate nitrogen in the furrow tended to remain fairly constant for the entire field during most the growing season, but reasons for the relatively high nitrate-nitrogen contents were not clear. After further examination of the analysis results for the furrow soil samples that showed increased nitrate-nitrogen content, it was obvious that there were substantial deviations in the measured values. These relatively high deviations in the measured values for several soil sample depths indicated spatial variabilities in the nitrate-nitrogen measurements.

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40 Table 2-10 contains the results from the statistical analysis of the data taken on those dates. Table 2-10. Statistical analysis of spring 2002 furrow soil samples nitrate-nitrogen results. Date Half Depth (cm) Average (kg/ha) Maximum (kg/ha) Minimum (kg/ha) Standard Deviation (kg/ha) 02/21/02 N 0-15 15-30 30-60 60-90 9.3 3.1 2.5 11.7 14.4 5.4 3.7 48.3 3.6 1.2 1.5 1.5 4.5 1.7 0.9 20.4 02/27/02 S 0-15 15-30 30-60 60-90 10.7 6.1 3.2 1.7 25.0 9.1 3.8 2.5 5.0 3.9 2.7 0.9 8.3 2.0 0.5 0.6 05/01/02 N 0-15 15-30 30-60 60-90 9.3 6.5 11.2 9.9 17.1 13.4 21.7 18.4 5.2 2.9 5.9 5.6 4.9 4.7 6.6 5.8 05/29/02 N 0-15 15-30 30-60 60-90 7.7 4.3 4.6 2.6 26.2 8.4 7.6 4.1 2.1 1.3 2.8 1.5 10.4 3.1 1.9 0.9 06/05/02 S 0-15 15-30 30-60 60-90 11.3 5.7 4.3 3.5 14.7 8.7 6.8 5.2 7.7 3.6 3.0 2.5 2.9 1.9 1.4 1.0 As shown in the Table 2-10, several of the layers had large variability in the measured values. For example, the samples taken on February 21, 2002 had significant variation between the maximum and minimum measured values in the nitrate-nitrogen contents for the soil samples taken at 60-90 cm. The maximum value was measured to be 48.3 kg/ha, which is relatively high when compared to the minimum value of 1.5 kg/ha. This accounts for the high average value of 11.7 kg/ha. When the maximum value is not included in the average for the 60-90 cm depth, a more reasonable average nitratenitrogen content of 2.6 kg/ha was obtained.

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41 In the soil samples taken on February 27, 2002, there was significant variation (coefficient of variation = 0.78) in the measured values for the samples taken at 0-15 cm. The majority of the samples varied from approximately 5.0 kg/ha to 6.5 kg/ha for the nitrate-nitrogen content, but there were two relatively high measured values of 10.5 and 25 kg/ha. The May 1, 2002 samples had a few discrepancies in the measured nitratenitrogen contents for all of the sample depths. The 0-15 cm samples had two large measured values of 11.4 and 17.1 kg/ha, while the remaining three samples had an average nitrate-nitrogen content of 6.0 kg/ha. The samples taken at 15-30 cm had two high measured values of 9.6 and 13.4 kg/ha, while the other measured values ranged from 2.9 to 3.8 kg/ha for nitrate-nitrogen. Two relatively high nitrate-nitrogen contents of 13.7 and 21.7 kg/ha were measured from the 30-60 cm samples. The three other samples taken at 30-60 cm averaged out to be approximately 7.0 kg/ha for nitrate-nitrogen. The 60-90 cm samples had two measured values of 18.4 and 13.2 kg/ha for the nitrate-nitrogen content. These two measured values are relatively high when compared to the three other soil sample measurements that ranged from 5.7 to 6.3 kg/ha for nitrate-nitrogen. There was slightly less variation in the measured nitrate-nitrogen contents for the samples taken on May 29, 2002. The average measured value was slightly higher than expected. Only one nitrate-nitrogen measurement of 26.2 kg/ha at 0-15 cm was significantly higher relative to the other sample measurements, whose values ranged from 2.4 kg/ha to 5.3 kg/ha for nitrate nitrogen. The high average nitrate-nitrogen content measured from the soil samples taken on June 6, 2002 can be attributed to variations in the measured values for all of the sample depths. There were no substantial deviations in

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42 the measured values, but there were noticeable increases for the measurements taken at each depth interval. After the analysis of these sample results, it was clear that measurement error was the likely cause of the high average total nitrate nitrogen content on the previously mentioned dates and that nitrate-nitrogen transport of the fertilizer was restricted to the bed. Crop monitoring As previously discussed, crop monitoring for the spring 2002 potato crop consisted of obtaining information from the farmer, visu al field observations of timing of certain phenological events, and crop biomass sampling during the growing season. The crop development was documented from weekly visits to the farm (Table 2-11). Table 2-11. Important dates related to planting, harvest, and phenological events (2002). Date Days After Planting Event North South North South Planting 02/12/02 02/15/02 0 0 Emergence 03/10/02 03/10/02 20 23 Tuber Initiation 04/01/02 04/01/02 42 45 Anthesis 04/01/02 04/01/02 42 45 Maximum LAI 04/20/02 04/20/02 61 64 Killed Date 05/17/02 05/18/02 91 92 Harvest 05/24/02 05/24/02 98 98 Biomass samples for the north half of the field were taken at 47, 68, and 80 days after planting. The biomass samples for the south half were taken at the same times as those listed for the north half, except for the first set of samples. The first biomass harvest taken for the south half was done at 56 days after planting. Total final yields based on all the potatoes harvested was 36.5 Mg/ha for the north half and 36.0 Mg/ha for the south half. The three biomass samples and final tuber yield were used to estimate total nitrogen uptake of the potato crop. The methods used to determine nitrogen uptake are

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43 identical to those previously discussed for the 2001 potato crop. The estimates calculated for the total nitrogen uptake provided critical information regarding the effectiveness of the reduced nitrogen and irrigation applied. Figure 2-10 compares the cumulative nitrogen applied to the total plant nitrogen uptake for the north and south halves of the field. The cumulative nitrogen includes the fertilizer applications shown in Table 2-6 plus nitrogen applied through the irrigation applied due to elevated nitrate-nitrogen concentrations (10 mg/L) of the irrigation well water. Figure 2-10 provides insight on how fertili zer and irrigation scheduling can be modified in order to reduce nitrate-nitrogen l eaching. This figure indicates that the potato plants on the north half of the field recovered 155 kg/ha of the total 364 kg/ha of nitrogen applied from the fertilizer applications and the irrigation, which is a 42% recovery of nitrogen. This was a major improvement from the 30% that was recovered during the 2001 season. The south half plants recovered 132.2 kg/ha of the total 316 kg/ha of nitrogen applied, which is also a 42% recovery of nitrogen. However, it is clear from the soil sample results that nitrogen was more readily available for crop uptake over the entire growing season on the south half of the field and that the lower irrigation reduced the rate that nitrogen leached out of the top 30 cm. More nitrogen was taken up on the north half despite that nitrogen was more readily available to the south half plants. This was mostly likely due to the differences in the planting dates (Table 2-11). The north half plants were planted earlier, so were able to take up nitrogen for a longer period of time. Also, there may have been some error in the extrapolated final dry tuber yield estimate because there were no nitrogen concentration measurements of the tubers, stems, and leaves at final harvest. The soil moisture results also show that the north half of the

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44 field was still being over irrigated, which resulted in the nitrogen quickly leaching out of the top 30 cm of the soil profile. 0 50 100 150 200 250 300 350 400 1/1/021/11/021/21/021/31/022/10/022/20/023/2/023 /12/023/22/024/1/024/11/024/21/025/1/025/11/02 DateNitrogen (kg/ha) N-Applied (North) N-Applied (South) North (Measured) South (Measured) Figure 2-10. Nitrogen applied and total crop uptake (2002). Error bars represent one standard deviation about the mean of the measured values. No standard deviation was calculated for the final point because point was extrapolated. Comparisons of Final Yield/Nitr ogen Lost and Nitrogen Applied Figures 2-11 and 2-12 show the general trend in the dry tuber yield and nitrogen lost in relation to total nitrogen applied. The data shown include information for all four treatments that were implemented during the 2001 and 2002 growing seasons. Note that the nitrogen applied is comprised of the fertilizer applications plus the nitrogen applied through the irrigation due to the elevated nitrate-nitrogen concentrations in the irrigation well water.

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45 0 1000 2000 3000 4000 5000 6000 7000 8000 050100150200250300350400450 Nitrogen Applied (kg/ha)Dry Tuber Yield (kg/ha) North 2001 South 2001 North 2002 South 2002 Figure 2-11. Comparison between the total nitrogen applied and the dry tuber yield. 0 50 100 150 200 250 300 350 050100150200250300350400450 Nitrogen Applied (kg/ha)Nitrogen Lost (kg/ha) North 2001 South 2001 North 2002 South 2002 Figure 2-12. Comparison between the total nitrogen applied and the nitrogen lost Figure 2-11 illustrates how the dry tuber yield is affected by the total amount of nitrogen applied over the growing season. The figure indicates that the yield usually increases with increasing fertilizer applications amounts. However, the results in the figure show that the yields are generally stable for the nitrogen fertilizer amounts applied during 2001 and 2002 growing season. As show n in Figure 2-11, the dry tuber yield

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46 ranges from 5,684 kg/ha for the south half of the field in 2002 to 6,840 kg/ha in 2001 for the north half of the field. The yield stability indicates that there is specific amount of nitrogen fertilizer that can be applied to the crop that will produce the maximum yield, and any additional fertilizer applied will result in negligible increases in dry tuber yield. Unlike the dry tuber yield, the nitrogen lost depends significantly on the amount of nitrogen applied. Figure 2-12 shows that as the nitrogen fertilizer application increases the amount nitrogen lost also increases. In 2001, 427 kg/ha of nitrogen fertilizer was applied to the north half of the field and 325.3 kg/ha was lost. On the south half of the field, the fertilizer applied was reduced to 394 kg/ha, which resulted in 310.3 kg/ha being lost. The nitrogen fertilizer applied in 2002 was lower than that applied in 2001. The total applied nitrogen to the north and south halves of the field was 364 kg/ha and 316 kg/ha, respectively. With the reduced fertilizer application amounts, the nitrogen lost was 208.5 kg/ha and 183.8 kg/ha for the north and south halves of the field, respectively, which is somewhat lower than that lost in 2001. This indicates that acceptable yields can be achieved at the project site with substantial reductions in nitrogen fertilizer amounts while still maintaining acceptable yields.

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47 CHAPTER 3 MODEL DESCRIPTION AND RESULTS An existing crop model was used to predict crop yield and nitrate-nitrogen transport for the spring 2001 and 2002 potato crops that were monitored at the project site. The primary goal was to properly calibra te the model using the data collected during the two growing seasons in order to accurately represent the potato crop system. The Decision Support System for Agrotechnology Transfer (DSSAT) Version 3.5 was the model used in the analysis of the potato crops. DSSAT is a product of the International Benchmark Sites for Network for Agrotechnololgy Transfer (IBSNAT) project and is well known throughout the world. The model was chosen because of its ability to accurately predict crop yield and nutrient uptake. DSSAT Model Description DSSAT is a shell that utilizes a collection of crop models in order to perform crop growth simulations. The primary use of the shell is to allow the user to enter, store, and retrieve information necessary for crop simulations, sensitivity analyses, model calibrations, and model validations. The DSSAT model simulates plant development based on plant processes, which are directly affected by interactions with the environment. Also, the model contains a graphical interface that permits the user to analyze and view model results. The graphical user interface can also be used to navigate between the various programs and models contained within DSSAT. The crop models contained in DSSAT include the CERES model (Tsuji et al., 1998 pp. 78-98)for grains, the CROPGRO model (Tsuji et al., 1998 pp. 99-128) for legumes, and the SUBSTOR

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48 model (Griffin, 1993) for potatoes. The SUBSTOR model was the only model used in the research conducted. All the models in DSSAT use the same nutrient transport and hydrologic routines and differ only in the met hods used for plant growth. Also, DSSAT is able to perform both seasonal and sequence analyses. Seasonal analysis relates to the temporal variability of weather within the growing season and from year to year. Sequence analysis allows the user to examine the behavior of the crop system over time. The minimum data required to run the crop model include a weather file, a soil file, a cultivar file, and a control file (FILEX). Weather data that is used by DSSAT includes measured data or stochastically generated data that is based on historic weather. The soil file contains various parameters and information that include porosity, drained upper limit, soil family, etc. for specific site locations and soil types. The crop file includes genetic coefficients that affect plant devel opment. FILEX contains information regarding management practices and references the executable file to the correct soil, weather, and crop files. The following is a brief model description of the DSSAT model. For a more detailed description of the methods used in the DSSAT model including equations, input file structure, etc, refer to Tsuji (1994) and Tsuji (1998). Also, the input files used in the crop growth simulations are shown in Appendix C. Hydrology Component The soil-water balance routines implemented in DSSAT are described by Ritchie (Tsuji et al., 1998 pp. 41-54) and are used to predict the vertical one-dimensional soilwater transport under variably saturated conditions within the soil profile. The soil-water budget is determined daily and predicts plant transpiration, root water adsorption, soil evaporation, runoff, infiltration, and drainage.

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49 Runoff and infiltration are determined using the USDA-Soil Conservation Service (SCS) curve number (CN) with a modification for layered soils. The antecedent moisture condition used to determine the CN is based on the moisture content in the top layer of soil. Runoff is calculated using the daily rainfall only, because it is assumed that irrigation does not affect runoff. The infiltration is defined as the difference between the total water applied (precipitation plus irrigation) and runoff. In order to determine the soil-water transport, the soil profile is divided into layers. When infiltration occurs, drainage is calculated using a cascading method that predicts the soil-water movement from one soil layer to the next. Drainage only occurs when the moisture content in a layer exceeds the drained upper limit (DUL). The volume of water that can drain out of a specified layer is the difference between the current moisture content and the DUL. The drainage is then calculated using a proportionality constant, which transports the water into the underlying layer. The volume of water drained from a layer in a day is dependent on the volume of water above the DUL. If the soil-water flux entering the soil layer exceeds the volume it can hold (saturated moisture content minus current moisture content), the excess water is moved into the lower layer. The potential evapotranspiration (PET) is calculated using a modified PriestlyTaylor (1972) equation. Parameters needed for the calculation include total daily solar radiation, maximum temperature, and minimum temperature. The calculated PET is then separated into potential evaporation and transpiration in order to determine the actual soil evaporation and actual plant transpiration. During evaporation, an upward water flux is calculated for the top four soil layers using a soil-water diffusivity function.

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50 Actual root water uptake is determined from the potential uptake per root length. Reduction factors are used to account for nonideal soil moisture content conditions. The uptake does not exceed the maximum daily uptake that is assumed to be 0.03 cm3 of water per cm of root. Nitrogen Component The nitrogen balance routines used by DSSAT estimate the nitrogen transformations, nitrate transport in the soil profile, and nitrogen uptake by plants. The nitrogen transformation routines include denitrification under anaerobic conditions, mineralization of organic nitrogen, and nitrification of ammonium. The model can also predict the transport of nitrogen in the soil profile. Urea and nitrate are assumed to be mobile in the soil profile, while organic nitrogen and ammonium are considered to be immobile. Also, the model assumes that the nitrogen located in a specific layer is uniformly distributed in the layer. The organic nitrogen is divided into humic material and organic matter. The organic matter is then separated into carbohydrates, cellulose, and lignin. Each type of organic matter is assigned a distinct decay constant that corresponds to maximum decay under non-limiting conditions. Factors that limit the decomposition of organic matter, which include moisture content, soil temperature, and the effect of the carbon/nitrogen ratio of the soils, are all accounted for in the decay calculations. The decomposition of humic material into inorganic nitrogen is calculated in a similar manner to the decay of organic matter, except the reactions occurs at a much slower rate and carbon/nitrogen of the soils is not taken into account. The nitrification of ammonium to nitrate is calculated using a potential nitrification rate that is based on the Michaelis-Menton kinetic function. This nitrification calculation

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51 method is independent of soil type and depends only on the ammonium concentration. Factors that reduce the nitrification rate, including temperature, soil moisture content, and soil ammonium concentration, are taken into account using an environmental limit on nitrification capacity that ranges from zero to one. Advection is the only mechanism considered in nitrate transport. As a result, nitrogen transport in the soil profile from layer to layer is only dependent on the soilwater transport calculated in the hydrology routines. The equations used to determine nitrate transport assume that the entire nitrate in the soil is in aqueous form. Ammonium and nitrate are the two nitrogen forms that are taken up to meet the nitrogen requirements of the plant. The nitrogen uptake from the soil is dependent on the amount of nitrogen in the soil and the demand by the plant. The plant demand for nitrogen is a function of the top weight, concentration of nitrogen currently in the vines, and the critical nitrogen concentration, which is the minimum amount of nitrogen required for maximum growth. The actual crop nitrogen uptake is affected by the soil moisture content, root length density, and nitrogen concentration in the soil solution. To account for moisture content, a soil water factor that ranges from zero to one is introduced that reduces the nitrogen uptake potential. Two additional reduction factors are then determined based on the ammonium and nitrate concentrations. Finally, the root length density factor is calculated to determine actual plant nitrate and ammonium uptake. Crop Growth Component During this study, the SUBSTOR-Potato Version 2.0 crop model was used to simulate the biomass accumulation and phenological development of the spring 2001 and 2002 Red LaSoda potato crops based on the soils, weather, and different management

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52 practices used at the project site. The SU BSTOR-Potato Version 2.0 was developed with the intent to be used over a wide range of geographical locations and for different cultivars. The inputs used in the potato growth simulation are retrieved from the weather file, soil file, cultivar file, and a temporary file made from the FILEX created by DSSAT. The temporary file is created by DSSAT so that the input file is converted to the format used by SUSTOR. The cultivar file includes five genetic coefficients that characterize crop growth and development. The five genetic coefficients located in the cultivar file include the leaf expansion rate (G2), tuber growth rate (G3), determinacy (PD), temperature (P2), and sensitivity of tuber initiation to photoperiod (TC). There are also several other crop growth parameters and coefficients that are located in the SUBSTOR code and species file that are species specific and should not be modified by the unknowledgeable user. Due to the large number of these parameters and coefficients, they are not listed here (refer to Griffi n et al., 1993). The SUBSTOR outputs include daily dry matter weights of the leaves, stems, tubers, and roots; daily leaf area index (leaf area per horizontal ground surface area); and the phenological growth stage. The simulation of crop development and growth is divided into five stages in SUBSTOR, which include pre-planting, pl anting to sprout germination, sprout germination to emergence, emergence to tuber initiation, and tuber initiation to maturity. In SUBSTOR-Potato model, the partitioning and accumulation of biomass during the computer simulation for the leaves, stems, tubers, and roots are dependent on the growth stage of the crop. Also, growth restrictions caused by high/low temperatures, long photoperiods, water stresses, and nitrogen stresses are all accounted for in the model.

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53 Model Calibration and Results In the original DSSAT simulation, Albert (2002) assumed that the computer simulation was restricted to the bed only. As a result, Albert doubled the fertilizer applications in the input file because it was presumed that this would be an appropriate method to concentrate the nitrogen fertilizer in the bed. After further examination of the source code and consultations with model developers, it was determined that DSSAT simulates plant growth for the entire row rather than just the bed. Because of the inconsistencies in Alberts (2002) approach for the spring 2001 potato crop growth simulations, the north half of the field that used the farmers typical management practices was re-simulated using a modified FILEX with the correct fertilizer amounts. All the previous soils data (i.e. CN, porosity, DUL, etc.) and plant generic coefficients (G2, G3, PD, P2, TC) were used in the new simulation. During the spring 2001 potato crop, soil sampling did not begin until March 2, 2001, which was well past the time of the pre-plant fertilizer application and planting. As a result, the initial conditions for soil moisture content were set equal to the measurements taken from the March 2, 2001 soil samples and initial nitrogen content was estimated. The initial nitrogen content measured on January 9, 2002 soil samples were used as initial nitrogen content for the 2001 simulation. In order to minimize effect of errors in initial conditions, the simulation was started on January 1, 2001, which was well before the first fertilizer application on January 18, 2001. The calibration of the model consisted of comparisons between the measured and simulated values for each sampling depth described in Chapter 2. The calibration comprised first adjusting the soil parameters in order to accurately represent the soil-water conditions in the soil profile. Initially, it appeared that the soil

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54 parameters needed no further adjustments from the values used by Albert (2002). This was concluded from the comparisons between the measured and predicted results shown in Figures 3-1 through 3-4. Note that the DSSAT simulation predictions illustrated in the figures represent weighted averages of the results for each soil layer listed in the output file in relation to the actual measurement depths. Also, remember that the DSSAT predictions were calculated daily, so the results represent the daily averages. The moisture content results for the corrected computer simulation displayed the same general trends as Alberts (2002) simulation. There were slight differences in the initial soil moisture content predictions because of the differences in the initial conditions used in each simulation. For example, at 0-15 cm the corrected model predicted the moisture content to 0.068 on January 7, 2001, while in Alberts (2002) simulation it was predicted to be 0.069. But in general, the moisture content predictions for the corrected simulation and Alberts simulation were virtually the same. The results indicate that the majority of the simulated values fairly accurately predicted the measured values. Most of the soil moisture predictions remained within one standard deviation of the measured values with the majority of the model predictions being greater than the measured values. The soil moisture predictions displayed very little variation over the growing season, except for the simulation results at 0-15 cm depth. The model predictions at 0-15 cm exhibited noticeable increases in the moisture content following every irrigation application and/or rainfall event. This was caused by the soil surface exposure to irrigation, rainfall, and evapotranspiration. Also, the magnitude of the increase depended on the amount of water applied to the field and the previous moisture content of the soil layer. For example, on January 20, 2001 there was

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55 a 7 mm rainfall event that resulted the simulated moisture contents to increase from 7.6% on January 19, 2001 to approximately 9% on January 20, 2001. The largest predicted moisture content observed occurred on March 16, 2001. Prior to March 16, 2001, the field received 4.5 cm of water from March 14, 2001 through March 18, 2001, which caused the predicted moisture content to increase from 8% on March 14, 2001 to almost 20% on March 18, 2001. The simulation results at 0-15 cm also provide valuable information of the soils ability to drain to field capacity relatively quickly, which is shown in the simulated moisture content results for March 24, 2001. By March 24, 2001, the moisture content of the top 15 cm reduced from the 20 to 8%. The decrease may be attributed to the evapotranspiration and drainage that occurred. The 4.5 cm of applied water also had significant impacts on the predicted moisture contents for the lower soil depths. 0.00 0.05 0.10 0.15 0.20 0.25 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01DateMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 80 90 100 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-1. DSSAT spring 2001 potato crop soil moisture content results for the north half at 0-15 cm. Error bars represent one standard deviation about the measured mean.

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56 0 0.05 0.1 0.15 0.2 0.25 0.3 1/1/011/21/012/10/01 3/2/013/22/014/11/015/1/015/21/01DateMoisture Content (cm3/cm3)0 10 20 30 40 50 60 1/1/011/21/012/10/01 3/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-2. DSSAT spring 2001 potato crop soil moisture content results for the north half at 15-30 cm. Error bars represent one standard deviation about the measured mean. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01DateMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-3. DSSAT spring 2001 potato crop soil moisture content results for the north half at 30-60 cm. Error bars represent one standard deviation about the measured mean.

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57 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-4. DSSAT spring 2001 potato crop soil moisture content results for the north half at 60-90 cm. Error bars represent one standard deviation about the measured mean. As expected, the maximum simulated moisture content also occurred on March 18, 2001 for the lower depths of 15-30, 30-60, and 60-90. After March 18, 2001, the predicted moisture contents for the lower layers remained relatively stable, but were slightly higher than the moisture contents predicted earlier in the season by 1-2%. The elevated moisture contents were caused by the daily 0.8 cm irrigation applications that began around April 1, 2001. Figure 3-5 shows the results for the water balance for the entire simulation period. No runoff was predicted during the entire simulation period. As a result, the total 71.5 cm of water received by the field was infiltrated into the soil surface. Fifty-four percent of the 71.5 cm water received by the north half of the field was lost by soil evaporation. Only 6.1 cm of water was taken up by the plant from the soil, while 21.8 cm was lost to deep drainage.

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58 Like the moisture content results, the water balance results for the corrected simulation compared relatively well to Alberts (2002) simulation. Approximately the same amount of drainage was predicted in both simulations. However, more transpiration and evaporation occurred during Alberts simulation. In Alberts simulation, the transpiration and evaporation was predicted to be 11 cm and 48 cm, respectively. The differences in the water balances were mostly likely caused by differences in crop growth for each computer simulation. 0 10 20 30 40 50 60 70 80 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01 DateWater (cm) Total Water Applied Soil Evaporation Plant Transpiration Drainage Figure 3-5. Cumulative water balance for the north half of the field for the spring 2001 potato crop. Similar to the moisture content predictions, the predicted nitrate-nitrogen concentrations compared relatively well to the measured values. Figures 3-6 through 3-9 show that DSSAT generally predicted the temporal and spatial changes in nitrate concentration within at least one standard deviation of the measured results. Also, the model responded appropriately to fertilizer applications and changes in moisture content for the entire soil profile, which is more apparent in the top 15 cm. The large changes

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59 were more evident in the top 15 cm because this zone in the soil profile was where the nitrogen fertilizer was applied and displayed the largest variations in moisture content. For example, the nitrate-nitrogen concentration prediction for the top 15 cm increased to 2,500 mg/L on March 8, 2001, which was caused by the 112 kg/ha of nitrogen fertilizer applied on March 5, 2001. On January 29, 2001, the nitrate-nitrogen concentration increased to 1,037 mg/L due to nine consecutive days with no water applied. Even though the model did predict most of the nitrate concentrations within on standard deviation, there were noticeable under predictions for the nitrate-nitrogen concentrations below the top 15 cm. For example, the March 2, 2001 soil samples had measured nitrate concentrations values of 603, 293, and 131 mg/L for the 15-30, 30-60, and 60-90 cm sampling depths, respectively. These measured values are significantly higher than the predicted values of 229 mg/L at 15-30 cm, 163 mg/L at 30-60 cm, and 90 mg/L at 60-90 cm. These results indicate that modeled nitrate may be leaching out of the soil profile too quickly, which could reduce the amount of applied nitrogen recovered by the potato crop. When the corrected simulation was compared to Alberts (2002) simulation results with the doubled fertilizer application rates, there were significant differences between the predicted values. For example, on March 8, 2001 the nitrate-nitrogen concentration was predicted to be 10,080 mg/L in the top 15 cm, which is approximately four times greater than the corrected prediction. On January 29, 2001, the nitrate-nitrogen concentration in the top 15 cm was approximately two and a half times greater than the corrected model prediction of 2,500 mg/L. Similar trends are observed through the

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60 duration of the computer simulation. Alberts (2002) results were usually two to four times larger than the corrected simulation predictions. 0 500 1000 1500 2000 2500 3000 3500 4000 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-6. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 0-15 cm. Error bars for the measured values represent one standard deviation about the measured mean. 0 200 400 600 800 1000 1200 1400 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001Total Water Applied (mm) Water Applied Measured Predicted Figure 3-7. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 15-30 cm. Error bars for the measured values represent one standard deviation about the measured mean.

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61 0 100 200 300 400 500 600 700 800 900 1000 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-8. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 30-60 cm. Error bars for the measured values represent one standard deviation about the measured mean. 0 100 200 300 400 500 600 700 800 900 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 1/1/20011/21/20012/10/20013/2/20013/22/20014/11/20015/1/20015/21/2001Total Water Applied (mm) Total Water Applied Measured Predicted Figure 3-9. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of the field at 60-90 cm. Error bars for the measured values represent one standard deviation about the measured mean. Noticeable differences were also observed between the predicted crop growth results for Alberts (2002) simulation and the corrected simulation. In Alberts results,

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62 the model tended to agree very well with the measured biomass values, especially dry tuber yield. For example, the predicted dry tuber yield was approximately 6,900 kg/ha, which is relatively close to the measured value of 6,840 kg/ha. Also, the results appeared to accurately represent the generally trend in leaf and stem growth relatively well, but were usually greater than the average measured values. The ageement between modeled and measured values was most likely due to the doubled fertilizer application rates, which provided more nitrogen for plant uptake during the simulation. When the corrected models plant growth predictions were examined, it was noticed that there were significant inaccuracies in the model simulations. The predictions compared relatively well to the analysis results from the four biomass sample sets collected by Albert (2002) for the dry leaf (F igure 3-10), dry stem (Figure 3-11), and dry tuber (Figure 3-12) weights. The first i ndication that DSSAT was inaccurate was when the final dry tuber yield predictions were compared to the actual measured yield. The measured dry tuber yield was determined to be 6,840 kg/ha while the predicted yield was 3,735 kg/ha. The 45% underprediction in dry tuber yield was substantial and the cause for the underprediction was not initially apparent. According to Alberts (2002) analysis results, the model predictions were accurate until final harvest. However, after evaluating the biomass collection method used by Albert (2002), it was determined that the technique used to collect the biomass samples was biased. The samples were taken on a per plant basis and the mass per area was then determined from the planting density. Early in the season the method would be somewhat correct, but it is virtually impossible to distinguish between individual plants once the vegetation is well developed later in the growing season. Thus, the biomass

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63 analysis results for the four sets of biomass samples contained a large degree of inaccuracy and the weight per plant was probably underpredicted, which was why the early model predictions were similar to the early measured values. However, it still was not clear why the model under predicted the final tuber yield. The genetic coefficients used for the Red LaSoda potato crop were reasonable and the moisture content predictions indicated that there was an ample amount of water available to the plant. After examining the nitrogen balance (Figure 3-13), it was clear that the model notably under predicted the amount of nitrogen that was taken up by the plants because the nitrate was leaching out of the root zone too quickly. 0 100 200 300 400 500 600 700 800 900 02/15/0102/22/0103/01/0103/08/0103/15/0103/22/0103/29/0104/05/0104/12/0104/19/0104/26/0105/03/0105/10/0105/17/01 DateLeaf Weight (kg /ha) Predicted Measured Figure 3-10. DSSAT dry leaf weight pred ictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the measured mean.

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64 0 50 100 150 200 250 300 350 02/15/0102/22/0103/01/0103/08/0103/15/ 0103/22/0103/29/0104/05/0104/12/0104/ 19/0104/26/0105/03/0 105/10/0105/17/01 DateStem Weight (kg/ha) Predicted Measured Figure 3-11. DSSAT dry stem weight pred ictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the measured mean. 0 1000 2000 3000 4000 5000 6000 7000 8000 02/15/0102/22/0103/01/0103/08/0103/15/0103/22/0103/29/0104/05/0104/12/0104/19/0104/26/0105/03/0105/10/0105/17/01 DateTuber Weight (kg/ha) Predicted Measured Figure 3-12. DSSAT dry tuber weight pred ictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the measured mean.

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65 0 50 100 150 200 250 300 350 400 450 1/1/011/15/011/29/012/12/012/26/013/12/013/26/014/9/014/23/015/7/015/21/01 DateNitrogen (kg/ha) Predicted N-Uptake N-Applied Predicted N-Leached Measured N-Uptake Figure 3-13. Cumulative nitrogen balance for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the mean. DSSAT predicted that only 58.4 kg/ha of the total nitrogen applied was utilized by the plant, which was 43.3 kg/ha below what was measured. This value is also significantly lower than that predicted in Al berts simulation. Since Albert doubled the fertilizer application, the plants took up more nitrogen over the computer simulation. The total nitrogen taken up was predicted to be approximately 101 kg/ha, which is much larger than the corrected model prediction. This also shows that Alberts dry tuber yield prediction was accurate because the increased nitrogen uptake resulted in more plant growth, and the accuracy of Alberts simulation was purely coincidental. Several combinations of the crops genetic coefficients were then used in various simulations, but none increased plant nitrogen uptake or yield. From these findings and the observations of low soil nitrate concentrations in the model predictions, it was determined that the nitrate was leaching out of the soil to quickly because the water balance was incorrect.

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66 As previously discussed, the soils located at the project site are sandy and tend to drain relatively quickly. All the samples taken in the field were obtained at times when the soils had drained to field capacity. So, while the steady-state drained water content was correct, the volume and rate of water moving through the profile seemed to be incorrect. This underscores the difficulty in calibrating the hydrology component in the model. However, the soil parameters were determined from lab experiments and were reasonable considering the characteristics of the soils located on the project site. After these findings, it was determined that the DSSAT hydrology component and plant growth component needed to be modified in order to account for the bed slope and canopy effects on infiltration; the fertilizer placemen t effects; and the bed width and depth to hard pan effects on root depth, root density, and nitrogen uptake.

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67 CHAPTER 4 DSSAT MODIFICATIONS After the initial DSSAT simulations for the spring 2001 potato crop, it was clear that DSSAT required modifications in order to properly simulated the potato crop system. The model underpredicted crop yield and overestimated the nitrate leaching. A possible source of the modeling error is that DSSAT assumes that water and nitrogen are uniformly distributed in each soil layer and that the field surface is flat. In actuality, the potato plants are planted in beds (Figure 41) that are maintained throughout the growing season. The beds, along with a underlying plow pan, reduced the volume of soil available to plant roots for water and nitrate-nitrogen uptake by approximately half (Figure 4-1). Figure 4-1. Illustrations of the potato pl ant beds (01/28/2003) and root distribution (04/12/2003). To investigate these issues and provide motivation and justification to modify DSSAT, the HYDRUS2D/MESHGEN vadose zone model was implemented. HYDRUS is a product of the International Ground Water Modeling Center and was developed at the

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68 U.S. Salinity Laboratory Riverside, California. HYDRUS was selected due to its ability to accurately predict two-dimensional soil-water and solute transport. The primary purpose of using HYDRUS was to give a general idea of how the nitrate-nitrogen was being transported through the soil. For examples of the HYDRUS input files, refer to Appendix D. HYDRUS Model Description HYDRUS is a Microsoft Windows based modeling environment used for the analysis of water and solute flow in a variable saturated porous media. HYDRUS includes the SWMS_2D two-dimensional finite element model for simulating water and solute transport and the MESHGEN-2D mesh generator to create unstructured finite element grids. The model has a graphical user interface that is used for creating input files, structured mesh generation, and a graphical presentation of the results. The input files required by HYDRUS vary depending on the simulation options selected by the user. The model has the ability to predict solute and water transport for both rectangular and irregularly shape boundaries. The model can simulate a maximum of six solutes during a simulation, whether they are independent of one another or if they are part of a chain species. Solute boundary conditions that are specified by the user include Dirichlet (boundary concentration) Cauchy (prescribed flux concentration), Neumann, and volatile types (e.g. volatilization of ammonia). Water transport boundary conditions are comprised of three system independent and three system dependent types. The three system independent boundary conditions include Dirichlet (specified pressure), Neumann (specified flux), and specified gradient types (free/deep drainage). The system dependent boundary conditions consist of an at mospheric type, seepage face type, and tile drain type. Each water transport boundary condition can be used in combination with

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69 any other water transport boundary condition, but two different boundary conditions types cannot be applied to the same boundary segment. The same is true for the solute transport boundary conditions. Also, the variable flux (Neumann type) and atmospheric boundary conditions are assigned one value per time step and are not allowed to vary spatially. Governing Flow Equation The model considers two-dimensional isothermal Darcian flow of water in variably saturated rigid porous medium and assumes the air phase flow is negligible. The governing flow equation for these conditions is given by a modified Richards equation (Eq. 4-1). S K x h K K x tA iz j A iij (4-1) where is the volumetric water content [L3L-3], h is the pressure head [L], S is a sink term [T-1], xi (i = 1, 2) are the spatial coordinates [L], t is time [T], Kij A are components of the dimensionless anisotropy tensor KA, and K is the following unsaturated hydraulic conductivity function [L T-1]: ) , ( ) ( ) , ( z x h K z x K z x h Kr s (4-2) where Kr is the relative hydraulic conductivity and Ks is the saturated hydraulic conductivity (L T-1). The anisotropy tensor is used to account for anisotropic conditions. The matrix becomes an identity matrix for an isotropic medium. If (4-1) is applied to planar flow in a vertical cross-section, x1 = x is the horizontal coordinate and x2 = z is the vertical coordinate (positive upward).

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70 Root Water Uptake The volume of water that is removed per unit time from a unit volume of soil is accounted for using the sink term ( S ) in (4-1). The root water uptake routines in HYDRUS are relatively simplified compared to the methods used by DSSAT. Unlike DSSAT, HYDRUS requires that the user specify the root distribution and it is considered to be static throughout the simulation. There are two main root water uptake functions used in HYDRUS that includes the Feddes and van Genuchten models. The root water uptake function used in the potato crop simulations was the Feddes model. The Feddes model is given by the following equation. pS h a h S ) ( ) ( (4-3) where a(h) is a dimensionless water stress response function and Sp is the potential water uptake rate [T-1]. The van Genuchten equation is similar to the Feddes equation, except the water stress function was expanded to account for osmotic stress. The potential root water uptake for a non-unifo rm root distribution of an arbitrary shape is defined as p t pT L z x b S ) ( (4-4) where Lt [L] is the width of the soil surface a ssociated with plant transpiration, Tp [L T-1] is the potential plant transpiration specified by the user, and b(x,z) is the normalized water uptake distribution [L-2]. The actual root water uptake is then determined by substituting (4-4) into (4-3): p tT L h a h S ) ( ) ( (4-5)

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71 The Unsaturated Soil Hydraulic Properties Unsaturated soil hydraulic properties, (h) and K(h) are generally highly nonlinear functions of the soil-water matric potential, which is dependent on soil texture (e.g. clay, sand, silt). HYDRUS utilizes three different analytical models to describe the hydraulic properties of soils. The models contained in HYDRUS include the Brooks and Corey (1964), the van Genuchten (1980), and Vogel and Cislervoa (1998) models. The soilmoisture characteristics curve for the soils located at the project site were fitted to the Brooks and Corey (1964) soil-water retention and hydraulic conductivity functions, which are given by 1 1 1 h h h Sn e (4-6) 2 / 2 l n e sS K K (4-7) respectively, where Se is the effective water content defined as follows r s r eS (4-8) where r and s are the residual and saturated moisture contents, respectively; Ks is the saturated hydraulic conductivity, h is the matric potential [L], is the inverse of the airentry pressure, n is the pore-connectivity index, an l is the pore-connectively parameter (assumed to be 2.0). HYDRUS considers l and n to be empirical coefficients that affect the shape of the hydraulic functions. To account for the spatial variability of the unsaturated soil hydraulic properties in the flow domain, HYDRUS uses a scaling procedure that simplifies the description of the variability. It is assumed that the hydraulic variability in a specified domain can be

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72 approximated using linear scaling transformations (refer to Simunek et. al, 1999 pp. 1819) that relate the individual soil hydraulic characteristics to reference characteristics. There are three independent scaling factor s that are used by HYDRUS, which define a linear model of the actual spatial variability in the soil hydraulic properties. Governing Transport Equation The HYDRUS model assumes solutes can exist as liquid, solid, and gaseous phases and that the decay and production processes can differ in each phase. For example, the liquid and solid phases can be described as nonlinear nonequilibrium equations, while the interactions between the liquid and gaseous phases can be assumed to be linear and instantaneous. The solutes are transported by advection and dispersion in the liquid phase and by diffusion in the gas phase. The partial differential equations governing twodimensional nonequilibrium solute transport involved in a sequential first-order decay chain during transient water flow in variably saturated rigid porous medium are given by v g s w v g g s s w w r i i j g ij v j w ij va g a s c Sc x c q x g D a x x c D x t g a t s t c1 1 1 1 / 1 1 1 / 1 1 1 / 1 1 1 1 1 1 1 1 1 1 1 (4-9) ) 2 ( , , 1 / 1 1 / 1 1 / 1 / , / , / , , s k r v k g k g k w k v k g k k s k k w k v k g k g k k s k s k k w k w i k i j k g k ij v i j k w k ij i k v k kn k Sc a g a s c g a s c x c q x g D a x x c D x t g a t s t c (4-10) where c s and g are solute concentrations in the liquid [M L-3], solid [M M-1], and gaseous [M L-3] phases, respectively; qi is the i-th component of the volumetric flux density [L T-1]; w, s, and g are first-order rate constants for solutes in the liquid, solid,

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73 and gas phases [T-1], respectively, w /, s /, and g / first-order rate constants for solutes in the liquid, solid and gas phases [T-1], respectively, for a chain species, w, s, and g are zero-order rate constants for the liquid [M L-3 T-1], solid [T-1], and gas [M L-3 T-1], respectively; is the soil bulk density [M L-3], av is the air content [L3 L-3], S is the sink term in the water flow equation (4-1), cr is the concentration of the sink term [M L-3], Dij w is the dispersion coefficient tensor [L2 T-1] for the liquid phase, and Dij g is the diffusion coefficient tensor [L2 T-1] for the gas phase. The subscripts w s and g correspond to the liquid, solid, and gas phases, respectively; the subscript k represents the k th chain number, and ns is the number of solutes in the chain reaction. The nine zero-order and first-order rate constants in (4-9) and (4-10) can be used to represent a variety of reactions or transformations that include biode gradation, volatilization, and precipitation. HYDRUS assumes equilibrium interactions between the solution and gas phases of the solute in the soil system. In the graphical user interface, the user can specify nonequilibrium or equilibrium conditions between the solution and solid phases of the solute in the soil system. A generalized nonlinear equation (4-11) is used to describe the adsorption isotherm relating the solid and solution phases of the solute in the soil system. t c c c k t c c k t k c c t c c c k t s c c k sk k k k k k s k k k k k s k s k k k k k k k k k s k k k k k s kk k k k k k k k k k 2 2 2 , 2 1 s ,1 ln 1 1 1 n 1, k 1 (4-11) where ks,k [L3 M-1], k [-], and k [L3 M-1] are empirical coefficients. Equation (4-11) can be used to represent Langmuir (k=1), Freudlich (k=0), and linear (k=1 and k=0) adsorption isotherms. Solute transport without adsorption is represented by ks,k=0. The empirical coefficients are assumed to be i ndependent of solute concentration, but are

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74 allowed to change as a function of temperature if the user selects the option. The concentrations of the solution and gas phases are related by the linear equation k k g kc k g, (4-12) where kg,k is an empirical constant [-] that is to ( KHRuTA)-1. KH is Henrys Law constant [M T2 M-1 L-2], Ru is the universal gas constant [M L2 T-2 K-1 M-1], and TA is the absolute temperature [K]. HYDRUS Results and DSSAT Modifications HYDRUS Results The HYDRUS model was used to simulate nitrate transport for both flat and bedded soil surfaces in order to investigate the influences of model geometry and fertilizer placement on water and nitrate-nitrogen transport. The first simulation was based on the DSSAT geometry, which assumes that the field is flat and that the nitrogen fertilizer is evenly distributed across the entire field. The fertilizer was applied uniformly over the entire soil surface. The second run simulated the two-dimensional bedded surface to demonstrate the effects of the bed shape and fertilizer placement on water and nitrate-nitrogen transport. In the second simulation, the fertilizer application was introduced in the soil profile using two circular 1 cm diameter variable boundaries with specified fluxes to simulate the field practice of banding the nitrogen fertilizer in the beds. Both simulations received identical fertilizer application amounts. To illustrate the differences between the flat and bedded soil surfaces, the nitrate transport of the January 10, 2002 fertilizer application (refer to Table 2-6) on the north half of the field was analyzed. The rainfall and irrigation applied during the HYDRUS simulation was identical to that used in the DSSAT simulations. The transport of the January 10, 2002

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75 fertilizer application was analyzed because there were significant amounts of rainfall received by the crop over this period. Over the duration of the simulation, there were three consecutive rainfall events of 1.1, 0.8, and 4.9 cm that occurred from January 12, 2002 through January 14, 2002, respectively, which contributed to the relatively rapid nitrate-nitrogen leaching. Note that HYDR US does not determine runoff and any water that does not infiltrate is immediately removed from the soil surface. The boundary conditions used for the upper and lower boundaries of the soil profile were atmospheric and free drainage, respectively. It is required in HYDRUS that the user specifies the potential evaporation and potential transpiration in the input file for atmospheric boundary conditions. Thus, the potential evaporation and potential transpiration that was calculated by DSSAT was used in the HYDRUS simulation. Plant roots were distributed evenly in the soil profile to a maximum depth of 30 cm in the HYDRUS simulations in order to account for plant root uptake effects on nitratenitrogen concentration and moisture content. The default parameters contained in HYDRUS for potatoes were used to estimate the root water uptake, however the wilting point was reduced from 000 to ,000 cm due to instabilities in the model at low moisture contents. Flow was assumed to be symmetrical from row to row, so no flux boundary conditions were used in the center of each furrow. Soil parameters for porosity, wilting point, bulk density, hydraulic conductivity are the same as those used in DSSAT. Figure 4-2 through Figure 4-4 are the soil-moisture characteristic curves (SMCC) for the soils at the project site.

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76 1 10 100 1000 10000 0.120.170.220.270.320.37 Moisture Content Hydraulic Conductivity (cm/day) 0-45 cm 45-90 cm Figure 4-2. SMCC of the hydraulic conductivity versus moisture content using the Brooks and Corey equation. 0 1000 2000 3000 4000 5000 6000 00.050.10.150.20.250.30.350.40.45 Moisture ContentMatric Potential (cm) Figure 4-3. SMCC of the soil matric potential versus moisture content for the top 45 cm of the soil profile using the Brooks and Corey equation. Note the points represent measured values.

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77 0 1000 2000 3000 4000 5000 6000 00.050.10.150.20.250.30.350.4 Moisture ContentMatric Potential (cm) Figure 4-4. SMCC of the soil matric potential versus moisture content for the bottom 45 cm of the soil profile using the Brooks and Corey equation. Note the points represent measured values. Nitrogen transport and degradation parameters were based on the values used by Albert (2002). The fertilizer was applied to the field as ammonium-nitrate with equal portions of each nitrogen species. The degradation of the compound from ammonium to nitrate was calculated for the entire nitrification chain (refer to Chapter 1) using firstorder kinetics. The sorption of ammonium to the soil colloids was modeled as a Langmuir Isotherm. Both sets of parameters for sorption and degradation were based on default values for sandy soil contained in an example problem in the HYDRUS program. Both sets of results for the flat (Figure 4-5) and bedded (Figure 4-6) indicate that nitrate is transported rapidly out of the soil profile regardless of the upper boundary condition. Figure 4-7 shows that the flat row simulation begins to leach nitrate out of the

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78 bottom of the profile sooner than the bedded row, but both cases leach nitrate at the same rapid rate on day 5 (01/14/02) when 4.9 cm of rainfall occurred. Figures 4-5 and 4-6 show that until day four, most of the nitratenitrogen remained in the top 30 cm of the soil profile, which encompasses the root zone. On day 5 of the simulation, 4.9 cm of rainfall infiltrated into the soil profile, which caused the nitrate-nitrogen to move into the bottom 30 cm of the soil profile and out of the root zone for both simulations. It should also be noted, however that HYDRUS does not account for canopy effects, which likely reduce infiltration rates for the potato crop system. In the flat row simulation, the nitrate-nitrogen transport is virtually onedimensional, while the bedded simulation displays two-dimensional transport of the nitrate-nitrogen in the soil profile due to the limited lateral dispersion in the soil profile. The bedded simulation results show that there are significant increases in the nitrate concentrations in the bed when the fertilizer is band applied. The maximum nitratenitrogen concentrations for the bedded surface were generally two to three times greater than those for the flat surface. Also, the nitrate-nitrogen was concentrated in the bed, particularly the root zone, which provides more nitrogen was available for plant uptake. Thus, the results of the HYDRUS simulations indicate that although nitrate moves at the same rate through the flat and bedded simulations (especially when canopy effects are neglected) the nitrogen remains concentrated in the root zone in the bedded simulations, which is very important for accurately simulating plant growth. This illustrates the importance of incorporating the actual bed geometry in the DSSAT model.

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79 0E3 6E3 1E3 2E3 3E3 4E3 5E3 0E3 3000 500 1000 1500 2000 2500 (a) (b) 0 250 500 100 150 200 40 180 60 80 100 120 140 160 (c) (d) 10 80 20 30 40 50 60 70 (e) Figure 4-5. Flat upper boundary nitrate concentration spectral map for the top 90 cm on the north half of the field for 01/10/02 through 01/14/02 (a-e). Spectral scale units are in mg/L.

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80 0E3 20E3 2E3 4E3 6E3 8E3 10E3 12E3 14E3 16E3 18E3 0E3 6E3 1E3 2E3 3E3 4E3 5E3 (a) (b) 0 450 50 100 150 200 250 300 350 400 0 250 50 100 150 200 (c) (d) 0 70 10 20 30 40 50 60 (e) Figure 4-6. Irregularly shaped upper boundary nitrate concentration spectral map for the top 90 cm on the north half of the field for 01/10/02 through 01/14/02 (a-e). Spectral scale units are in mg/L.

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81 0 5 10 15 20 25 30 35 1/9/20021/10/20021/11/20021/12/20021/13/20021/14/20021/15/20021/16/20021/17/20021/18/2002 DateNitrate-Nitrogen Leached (kg/ha) Flat Row Bedded Row Figure 4-7. Cumulative nitrate-nitrogen leached out of the top 90-cm from the January 10, 2002 fertilizer application. These results, along with the field observations, show that to improve its predictive ability, the DSSAT model should be modified to reduce the amount of soil volume accessible by the plant roots, concentrate the applied fertilizer into the beds, and reduce the amount of infiltration due to canopy effects. The next step was to review the DSSAT source code and make the proper modifications within the code to account for these conditions. DSSAT Modifications Before any modifications were made to the model, one of the DSSAT model developers, James W. Jones, was consulted in order to determine the necessary changes in the DSSAT source code. As previously stated, the goal was to reduce the soil volume accessible to the plant roots and concentrate the fertilizer applications in the beds. Following Dr. Joness suggestions, it was decided that the best approach for modifying DSSAT was to leave the water balance unchanged, while making all the needed changes

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82 in the crop growth module (GROSUB). Since the water balance was the same, it was necessary to change the row width used in the DSSAT input file to the bed width, which reduced the amount of soil volume available to plants by 50%. In order to account for the fertilizer applications being concentrated in the beds, the fertilizers application rates in the input file were doubled to concentrate the fertilizer applications in the bed rather than distribute the application across the entire field. The source code was then modified, with the aid of Cheryl Porter and Dr. James Jones of the Agricultural and Biological Engineering Department at the University of Florida, in order to maintain the same light interception by the potato plants in spite of us ing bed width rather than row width as the basis of the simulation. In the GROSUB module, the potato plants are grown as individual plants and the variable PLTPOP is the number of plants per square meter at emergence. The daily growth is calculated by dividing the overall growth per square meter by the plant population. The leaf area index (LAI) is calculated by multiplying the leaf area per plant (PLA) by PLTPOP. Plant biomass per meter square ground area is determined by multiplying the biomass per plant by PLTPOP to get plant mass per ground area. In order to account for the plants being grown on a bed area basis rather than on a row basis (Figure 4-8), the PLTPOP must be entered as plants per bed area rather than plants per row area in the input file. This allows the soil computations to remain the same. Since the model simulates plant growth on a row area basis, the actual LAI must then be calculated by multiplying the LAI computed on a bed basis by BWRATIO (bed width/row width). The variable BWRATIO is not included in the input file so it is declared locally in the GROSUB module.

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83 Light Interception and Root Domain Light Interception Domain Root Domain (a) (b) Figure 4-8. A comparison of the light inte rception and root domain for flat (a) and bedded (b) rows. The daily growth (PCARB, grams per plant per day) accounts for the plant growth on a row area basis. Since the LAI has already been modified to account for the entire row area, the daily growth is then computed on a row area basis. The daily growth must then be calculated on a bed area basis by dividing PCARB by BWRATIO. The resulting biomass output file is then on a bed area basis and must be multiplied by BWRATIO in order to convert them to a row area basis. The LAI in the output file is on a row area basis and does not need to be adjusted. To review the actual changes in the source code refer to Appendix E. The dense plant canopy (Figure 4-9) and steep bed slope have a major influence on the amount of effective rainfall infiltrating in to the plant bed. However, the SCS curve number method used in the DSSAT model does not adequately predict the reduction in infiltration caused by the bed slope and potato plant canopy. As a result, the infiltration that occurs over the growing season usually results in the model leaching the nitrogen fertilizer out of the soil profile too quickly with significant under predictions in dry tuber

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84 yield (Chapter 3). In an attempt to account for the bed and canopy effects on infiltration, a modified SCS curve number curve number was introduced. Determination of the modified CN was primarily comprised of increasing the CN until the nitrate-nitrogen concentration and moisture content results, shown in the following chapter, agreed relatively well with the measured values. The modified CN is necessary to decrease the infiltration in the bed, which should increase the nitrogen available to the potato plants and significantly increase plant growth. Note that a more physically-based method should be developed for future research for potato crops grown on sandy soils, which can accurately predict the spatial and temporal variability in the effective rainfall and the localized runoff caused by the developing plant canopy and bed slope. Figure 4-9. Potato plant canopy illustration.

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85 CHAPTER 5 MODIFIED DSSAT RESULTS AND DISCUSSION After all the appropriate modifications were made in the DSSAT source code and in the input files, the model was then calibrated using both the spring 2001 and 2002 potato crop data. The calibration methods for the modified model were the similar to those discussed in Chapter 3. The genetic coefficients for crop growth used by the model were the same as those used by Albert (2002). Soil parameters including porosity, drained upper limit, wilting point, drainage co efficient (SWCON), and porosity were also identical to those used by Albert, except the CN was increased from 75 to 95 in order to account for plant canopy and bed slope effects on infiltration. Note that the irrigation and rainfall were not modified for the bed simulation because the water was applied uniformly over the soil surface. As previously stated, the spring 2001 potato crop received similar management practices on the north and south halves of the pivot, so only the north half results will be shown in this section. Since the spring 2002 potato crop had more pronounced differences between management practices on the north and halves, simulation results for both the north and south halves of the field are included in this section. Refer to Appendix F for the modified DSSAT input files. Soil-Water Transport Results 2001 Potato Crop Figures 5-1 through 5-4 illustrate the insensitivity of the soil moisture prediction from the DSSAT model to changes in the volume of infiltrating water. Even with the increased CN, the model still tended to agree quite well with the measured values and

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86 displayed the same general temporal and spatial changes in the moisture contents as the previous simulation results shown for the 2001 crop discussed in Chapter 3. However, the peaks in the moisture contents were usually 1-3% lower using the modified model relative to the previous simulation, because of the decreased infiltration volume due to the increased CN. Even though the increased CN had a small effect on the predicted moisture content results, there were noticeable differences between the original DSSAT model and the modified model for the cumulative water balance (Figure 5-5). Unlike the previous simulations (Figure 3-5), localized runoff (to the furrows) occurred because of the increased CN. Thus, the cumulative infiltration in the beds was reduced by 4.88 cm and the drainage decreased from 21.8 to 17.6 cm due to the runoff. 0.00 0.05 0.10 0.15 0.20 0.25 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-1. Comparisons between the predicted and measured moisture contents at 0-15 cm for the north half of the field 2001 potato crop. Error bars represent one standard deviation about the average measured value.

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87 0 0.05 0.1 0.15 0.2 0.25 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-2. Comparisons between the predicted and measured moisture contents at 15-30 cm for the north half of the field 2001 potato crop. Error bars represent one standard deviation about the average measured value. 0 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-3. Comparisons between the predicted and measured moisture contents at 30-60 cm for the north half of the field 2001 potato crop. Error bars represent one standard deviation about the average measured value.

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88 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeMoisture Content (cm3/cm3)0 10 20 30 40 50 60 70 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-4. Comparisons between the predicted and measured moisture contents at 60-90 cm for the north half of the field 2001 potato crop. Error bars represent one standard deviation about the average measured value. 0 10 20 30 40 50 60 70 80 1/1/011/21/012/10/013/2/01 3/22/014/11/015/1/015/21/01 DataWater (cm) Total Water Applied Plant Transpiration Soil Evaporation Drainage Runoff Figure 5-5. Cumulative water balance for the north half of the field for the spring 2001 potato crop.

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89 The cumulative transpiration almost doubled, increasing from 6.2 to 11.6 cm. The increase in transpiration was most likely caused by an increase in the nitrogen recovered by the plants, which directly affects the growth of the plant biomass. The larger amount of nitrogen recovered caused the plant growth to increase, which increased the model predictions for LAI. The larger LAI in turn increased the potential transpiration calculated by the model. 2002 Potato Crop Similar results for the models moisture content predictions were observed for the 2002 crop. Figures 5-6 through 5-9 depict the spatial and temporal moisture content predictions for the north and south halves of the field. The model is relatively accurate in predicting the soil moisture contents for most of the depth increments over the 2002 growing season, considering the methods used for the water balance. Similar to the 2001 moisture content results, the predicted moisture contents tend to be stable, ranging from 8-11%, for the majority of the growing season. Also, the soil moisture content model predictions illustrate how the soil tended to remain at or above field capacity. The model appears to behave correctly because there are significant moisture content increases following a rainfall event or irrigation application, primarily in the top 30 cm. The model drains the soil to field capacity within four to five days following the rainfall event or irrigation application. The water balances for the north (Figure 5-10) and south (Figure 5-11) halves of the field indicate that there are noticeable differences in the drainage that occurred on each half of the field. The south half of the field received 7.1 cm less irrigation than the north half of the field. The reduction in water resulted in 6.1 cm less water draining out

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90 of the 90 cm soil profile. Like the 2001 crop season, the decrease in irrigation reduced the rate nitrate-nitrogen leached out of the soil profile. 0.00 0.05 0.10 0.15 0.20 0.25 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateMoisture Content (%)0 20 40 60 80 100 120 140 160 180 2001/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-6. Comparisons between the predicted and measured moisture contents at 0-15 cm for the 2002 potato crop. Error bars represent one standard deviation about the average measured value. 0.00 0.05 0.10 0.15 0.20 0.25 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateMoisture Content (%)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Applied S Measured N Measured S Predicted N Predicted S Figure 5-7. Comparisons between the predicted and measured moisture contents at 15-30 cm for the 2002 potato crop. Error bars represent one standard deviation about the average measured value.

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91 0.00 0.05 0.10 0.15 0.20 0.25 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateMoisture Content (%)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-8. Comparisons between the predicted and measured moisture contents at 30-60 cm for the 2002 potato crop. Error bars represent one standard deviation about the average measured value. 0.00 0.05 0.10 0.15 0.20 0.25 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateMoisture Content (%)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-9. Comparisons between the predicted and measured moisture contents at 60-90 cm for the 2002 potato crop. Error bars represent one standard deviation about the average measured value. Even though the cumulative irrigation and rainfall were approximately the same for both years, the predicted runoff for the 2002 crop season was significantly larger than

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92 that of the 2001 crop season. During the 2001 growing season, the runoff was calculated to be 4.88 cm, while the runoff calculated for the north and south halves of the field for the 2002 crop was determined to be 23.53 and 23.36 cm, respectively. The cause of the large difference between the two years is that the crop received more rainfall in 2002. The total rainfall for the 2001 and 2002 crops was 20.8 and 40.7 cm, respectively. DSSAT assumes runoff is only caused by rainfall, and that all the irrigation applied infiltrates into the soil profile. Therefore, since there was more rainfall in 2002, more runoff occurred. Also, there were different planting dates (Table 2-5) and management practices (Table 2-3) implemented on each half of the field in 2002, which resulted in different crop growth rates and soil moisture contents. The difference in growth rates directly affected the plant leaf area on each half of the field, which in turn affected the transpiration rates. The difference in the tran spiration rate, along with the variation in the irrigation management for each half of the fiel d, was the cause of the slight difference in the predicted cumulative runoff for the 2002 crop. 0 10 20 30 40 50 60 70 80 1/9/20021/29/20022/18/20023/10/20023/30/20024/19/20025/9/2002 DateWater (cm) Total Water Applied Drainage Soil Evaporation Plant Transpiration Runoff Figure 5-10. Cumulative water balance for the north half of the field for the spring 2002 potato crop.

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93 0 10 20 30 40 50 60 70 80 1/9/20021/29/20022/18/20023/10/20023/30/20024/19/20025/9/2002 DateWater (cm) Total Water Applied Drainage Soil Evaporation Plant Transpiration Runoff Figure 5-11. Cumulative water balance for the south half of the field for the spring 2002 potato crop. Even with fairly accurate soil-moisture predictions, it is still not clear that the models water balance is correct because the soil samples were taken at times when the soil moisture contents were approximately at field capacity. As a result, there is still significant uncertainty in the volume of water infiltrating past the root zone. It is difficult to determine if the models water balance is correct for the sandy soils located at the project site, because the soils have a tendency to drain to field capacity quickly. Nitrate-Nitrogen Transport Results 2001 Potato Crop Figures 5-12 through 5-15 depict the nitrate-nitrogen transport in the top 90 cm of the soil profile for the 2001 potato crop. The model appears to do a relatively good job predicting the nitrate transport in the soil. The majority of the predicted nitrate-nitrogen concentrations remain within one standard deviation of the measured values. With the

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94 decreased infiltration, the nitrate-nitrogen concentrations increased significantly. The figures show that the lower infiltration rates caused the nitrate-nitrogen concentrations to generally be two or more times greater than in the previous simulation predictions (refer to Chapter 3) due to the decreased leaching. 0 2000 4000 6000 8000 10000 12000 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 80 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Rainfall (mm) Total Water Applied Measured Predicted Figure 5-12. Comparisons between the predicted and measured nitrate-nitrogen contents at 0-15 cm for the north half of the field (2001). Error bars represent one standard deviation about the average measured value. 0 200 400 600 800 1000 1200 1400 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 80 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-13. Comparisons between the predicted and measured nitrate-nitrogen contents at 15-30 cm for the north half of the field (2001). Error bars represent one standard deviation about the average measured value.

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95 0 100 200 300 400 500 600 700 800 900 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01 TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 80 90 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-14. Comparisons between the predicted and measured nitrate-nitrogen contents at 30-60 cm for the north half of the field (2001). Error bars represent one standard deviation about the average value. 0 100 200 300 400 500 600 700 800 900 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01 TimeNO3 concentration (mg/L)0 10 20 30 40 50 60 70 80 90 1/1/011/21/012/10/013/2/013/22/014/11/015/1/015/21/01Total Water Applied (mm) Total Water Applied Measured Predicted Figure 5-15. Comparisons between the predicted and measured nitrate-nitrogen contents at 60-90 cm for the north half of the field (2001). Error bars represent one standard deviation about the average value. The largest increases in the nitrate-nitrogen concentrations are observed in the peak concentration values predicted by the model over the growing season, especially in the

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96 top 15 cm. For example, at 0-15 cm the peak nitrate-nitrogen concentration increased from the previous prediction of 2,497 mg/L on March 8, 2001 to 10,476 mg/L using the modified model. On March 28, 2001, the nitrate-nitrogen concentration was previously predicted to be 1,659 mg/L in the top 15 cm. The modified model predictions increased to 9,948 mg/L, which is approximately six times larger. These predicted nitrate-nitrogen concentrations, primarily in the top 30 cm, indicate that more nitrogen was available to the plants during the growing season during the model simulation. 2002 Potato Crop Figures 5-16 through 5-19 depict the nitrate-nitrogen concentrations for the 2002 crop. These figures provide illustrations of the general behavior of the soil system in response to fertilizer applications and rainfall/irrigation. The predictions for the 2002 crop did not compare as well to the measured values with the 2001 simulation results, but the predicted values generally fall within one to two standard deviations of the predicted values. The model does a fairly good job in predicting the nitrate-nitrogen concentrations in the top 30 cm, especially for the south half of the field. The majority of the predicted nitrate-nitrogen concentrations were larger than measured values at most depths. The over predictions are most likely caused by the decrease in the cumulative infiltration for the 2002 crop. The model predictions provide insight on the effectiveness of the reduced nitrogen and irrigation applied to the south half of th e field in 2002. The south half of the field had higher nitrate-nitrogen concentrations than the north half of the field for the majority of the growing season, despite the reductions in the fertilizer applications rates. This can be attributed to the 21% reduction in the irrigation applied to the south half of the field and the fertilizer application timing. The higher nitrate-nitrogen concentrations result in

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97 higher nitrate-nitrogen recovery in the south half crop relative to the north half of the field. 0 1000 2000 3000 4000 5000 6000 7000 8000 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateNitrate Concentration (mg/L)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied Total Water Applied Measured N Measured S Predicted N Predicted S Figure 5-16. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 0-15 cm (2002). Error bars represent one standard deviation about the average measured value. 0 200 400 600 800 1000 1200 1400 1600 1800 1/1/20021/21/20022/10/20023/2/ 20023/22/20024/11/20025/1/2002 dateNitrate Concentration (mg/L)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-17. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 15-30 cm (2002). Error bars represent one standard deviation about the average measured value.

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98 0 200 400 600 800 1000 1200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateNitrate Concentration (mg/L)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-18. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 30-60 cm (2002). Error bars represent one standard deviation about the average measured value. 0 100 200 300 400 500 600 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002 dateNitrate Concentration (mg/L)0 20 40 60 80 100 120 140 160 180 200 1/1/20021/21/20022/10/20023/2/20023/22/20024/11/20025/1/2002Total Water Applied (mm) Total Water Applied N Total Water Applied S Measured N Measured S Predicted N Predicted S Figure 5-19. Comparisons between the predicted and measured nitrate-nitrogen concentrations at 60-90 cm (2002). Error bars represent one standard deviation about the average measured value.

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99 Crop Growth Results After it was determined that the soil moisture contents and nitrate-nitrogen concentrations predicted by the model were relatively accurate for both years, the nitrogen balances and crop growth results were then evaluated. The two main purposes for examining the nitrogen balances and crop growth results were to evaluate the improvements in the models crop growth predictions and nitrogen uptake for the 2001 potato crop, and to evaluate the models accuracy for the 2002 crop. 2001 Potato Crop Figure 5-20 shows the cumulative nitrogen balance predicted by DSSAT and accuracy of the models nitrogen uptake predictions. The figure shows that there was a significant improvement in the nitrogen uptake prediction made by modified model compared to the original model (Chapter 3). The model prediction for plant nitrogen uptake increased from 58.5 kg/ha to 115 kg/ha, approximately two times the original prediction. The figure shows that the model predicted approximately 252 kg/ha of nitrogen leached out of the soil profile, while the crop recovered only 27% of the nitrogen fertilizer applied to the field. The increased predictions in the nitrogen uptake also significantly increased the crop growth prediction made by the model previously (Chapter 3). Figures 5-21 through 5-23 show the comparisons between the predicted and measured crop growth for the leaves, stems, and tubers, respectively. The results show that the model predictions for the leaves, stems, and tubers significantly increased due to the modifications. For example, the maximum predicted leaf weight increased from 200 kg/ha to approximately 380 kg/ha. The maximum stem weight increased from the previous prediction of 150 kg/ha to 275 kg/ha. These predictions for the leaf and stem

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100 weights were usually greater than the measured values, which was a result of the sampling methods used during the 2001 growing season (Chapter 2). 0 50 100 150 200 250 300 350 400 450 1/1/011/15/011/29/012/12/012/26/013/12/013/26/014/9/014/23/015/7/015/21/01 DateNitrogen (kg/ha) Predicted N-Uptake N-Applied Predicted N-Leached Measured Uptake Figure 5-20. Cumulative nitrogen balance for the 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the average value. Note that the error bars for the first three sample points are present, but are several orders of magnitude smaller than the scale used for the y-axis. 0 100 200 300 400 500 600 700 800 900 02/15/0103/07/0103/27/0104/16/0105/06/01 DateLeaf Weight (kg dm/ha) Predicted Measured Figure 5-21. Dry leaf weight predictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the mean measured value.

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101 0 50 100 150 200 250 300 350 02/15/0103/07/0103/27/0104/16/0105/06/01 DateStem Weight (kg/ha) Predicted Measured Figure 5-22. Dry stem weight predictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the mean measured value. 0 1000 2000 3000 4000 5000 6000 7000 8000 02/15/0103/07/0103/27/0104/16/0105/06/01 DateTuber Weight (kg/ha) Predicted Measured Figure 5-23. Dry tuber weight predictions for the spring 2001 potato crop on the north half of the field. Error bars represent one standard deviation about the mean measured value.

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102 The most notable improvement in the model predictions for dry weight is shown in Figure 5-23 of the dry tuber yield. The origin al model estimated the final dry tuber yield to be approximately 3,800 kg/ha, which is substantially lower than the measured value of 6,840 kg/ha. With the modifications, the predicted final dry tuber yield increased to 6,925 kg/ha, which is 3,125 kg/ha greater than the previous predictions. These results show that the modifications in GROSUB improved the models ability to predict the nitrogen recovery and crop growth for the potato crop grown on the sandy soils at the project site. 2002 Potato Crop Figures 5-24 and 5-25 are good illustrations of the nitrogen transport in the soil and the models accuracy in predicting crop nitrogen uptake. The model predictions for the nitrogen uptake agree quite well with the measured values. However, the results for the nitrogen uptake predictions for the south half of the field agree with the measured values better than those for the north half of the field. The model predicted that the crop nitrogen uptake was 141 kg/ha for the south half of the field, which relatively close to the estimated value of 132 kg/ha. The measured nitrogen uptake for the north half of the field was 155.5 kg/ha, which is much larger than the 107 kg/ha predicted. The underestimate in the nitrogen recovered by the plants in the north half can be attributed to the 7.1 cm of additional irrigation applied to th e north half of the field, which resulted in the model predicting more nitrogen being leached out of the zone occupied by the plant roots. This can also be seen in the nitrate-nitrogen results shown in Figures 5-16 through 5-19. Notice that the nitrate-nitrogen concentrations for the bottom 30 cm of the soil profile of the south half of the field are appr oximately two times greater than those for the north half of the field at the end of the gr owing season. This shows that more nitrogen

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103 was retained in the soil profile at the end of the growing season on the south half of the field. 0 50 100 150 200 250 300 350 400 1/1/021/11/021/21/021/31/022/10/022/20/023/2/023/12/023/22/024/1/024/11/024/21/025/1/025/11/02 DateNitrogen (kg/ha) Predicted N-Uptake N-Applied Predicted N-Leached Measured N-Uptake Figure 5-24. North half cumulative nitrogen balance for the2002 potato crop. Error bars represent one standard deviation about the average measured value. 0 50 100 150 200 250 300 350 1/1/021/11/021/21/021/31/022/10/022/20/023/2/023/12/023/22/024/1/024/11/024/21/025/1/025/11/02 DateNitrogen (kg/ha) Predicted N-Uptake N-Applied Predicted N-Leached Measured N-Uptake Figure 5-25. South half cumulative nitrogen balance for the 2002 potato crop. Error bars represent one standard deviation about the average measured value. Figures 5-26 through 5-31 contain the model predictions for the crop development over the growing season. The figures show that the model was able to predict the overall

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104 trends in the plant development, but tended to over estimate the dry stem and leaf weights. The dry weight predictions for the leaves and stems generally fell within one to two standard deviations the measured values. 0 500 1000 1500 2000 2500 02/12/0202/22/0203/04/0203/14/0203/24/0204/03/0204/13/0204/23/0205/03/0205/13/0205/23/02 DateLeaf Weight (kg dm/ha) Predicted Measured Figure 5-26. North half dry leaf weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value. 0 500 1000 1500 2000 2500 02/12/0202/22/0203/04/0203/14/0 203/24/0204/03/0204/ 13/0204/23/0205/03/02 05/13/0205/23/02 DateLeaf Weight (kg dm/ha) Predicted Measured Figure 5-27. South half dry leaf weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value.

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105 0 200 400 600 800 1000 1200 1400 02/12/0202/22/0203/04/0203/14/0203/24/0204/03/0204/13/0204/23/0205/03/0205/13/0205/23/02 DateStem Weight (kg/ha) Predicted Measured Figure 5-28. North half dry stem weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value. 0 200 400 600 800 1000 1200 02/12/0202/22/0203/04/0203/14/0203/24/0204/03/0204/13/0204/23/0205/03/0205/13/0205/23/02 DateStem Weight (kg/ha) Predicted Measured Figure 5-29. South half dry stem weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value

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106 0 1000 2000 3000 4000 5000 6000 7000 8000 02/12/0202/22/0203/04/0203/14/0203/24/0204/03/0204/13/0204/23/0205/03/0205/13/0205/23/02 DateTuber Weight (kg/ha) Predicted Measured Figure 5-30. North half dry tuber weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value. 0 1000 2000 3000 4000 5000 6000 7000 8000 02/12/0202/22/0203/04/0203/14/0203/24/0204/03/0204/13/0204/23/0205/03/0205/13/0205/23/02 DateTuber Weight (kg/ha) Predicted Measured Figure 5-31. South half dry tuber weight predictions for the spring 2002 potato crop. Error bars represent one standard deviation about the mean measured value. Even though the predicted and measured results indicate that the 2002 potato crop recovered more nitrogen than the 2001 crop, the simulated and observed dry tuber yield were higher for the 2001 crop. There was more vegetative growth and less tuber growth

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107 during the 2002 growing season compared to the 2001 potato crop, which was primarily caused by the two different row widths used during the 2001 and 2002 potato crops. During the 2001 growing season, the row spacing was 101 cm, while in 2002 the row spacing was 90 cm. Since the plants were planted together more closely in 2002, there was more competition for light. As a result, more of the total daily plant growth was partitioned to vegetative growth rather than tuber growth during the 2002 growing season, which was also observed in the plant biomass samples taken in the field during the 2001 and 2002 growing. The model did particularly well in predicting the dry tuber yield, which is shown in Figures 5-30 and 5-31. As was observed in the field, the model predicted that the north half dry tuber yield would be higher than the south half dry tuber yield. The south half dry tuber yield prediction of 5,512 kg/ha agreed relatively well with the estimated value of 5,684 kg/ha, but the north halfs dry tuber yield results were not as accurate. The model predicted that the north half final dry tuber yield to be 5,564 kg/ha, which is somewhat lower than the estimated final dry tuber yield of 6,175 kg/ha. The under prediction in the north halfs dry tuber yield was most likely caused by the under prediction in the nitrogen uptake, which is shown in Figure 5-24. But in general, the calibration results for the 2001 and 2002 potato crops indicate that the model is fairly accurate in predicting potato crop system and show that the model is properly calibrated for potato crop systems on the project site.

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108 CHAPTER 6 CONCLUSIONS This research provided valuable insight on nitrate-nitrogen and water transport through the sandy soils at the project site and their effects on potato crop growth. The measured results illustrate the susceptibility of nitrogen leaching through the typical Floridian sandy soils located at the research site. The data collected also aided in the calibration and modifications of the DSSAT crop growth model and provided valuable insight regarding the general trends of the water and nitrate-nitrogen transport at the project site. The measured data show that the sandy soils at the project are highly susceptible to leaching nitrate-nitrogen following rainfall events and irrigation applications. As seen from the measured moisture content results for both years of data, the soils drain to field capacity relatively quickly. Thus, a considerable portion of the nitrogen fertilizer applied to the potato crop can leach out of the root zone and eventually into the underlying aquifer as a result of poor fertilizer management and irrigation scheduling. The data collected in 2001 show that 24% of the total nitrogen applied (fertilizer plus irrigation nitrate-nitrogen) to the north half of the field was recovered by the potato plants, leaving 325 kg/ha of the 427 kg/ha nitr ogen applied in the fertilizer and irrigation to be leached out of the soil profile and into the underlying Floridan Aquifer. The data show that after rainfall events and irrigation applications, the nitrate-nitrogen moved quickly out of the top 30 cm and into the subsequent 60 cm, beneath the active root zone. This indicates the importance of proper irrigation and fertilizer management.

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109 The 2002 data also indicate that the potato crops currently grown at the project site are receiving more than adequate amounts of nitrogen fertilizer and irrigation. It was observed that the south half of the field, which received a 10% reduction in the 292 kg/ha of nitrogen fertilizer and a 21% reduction in the 343 mm irrigation applied, had a 491 kg/ha lower yield relative to the 6,175 kg/ha nor th half dry tuber yield. Also, the potato plants on the south half of the field recovered 23.3 kg/ha less nitrogen fertilizer than the 155.5 kg/ha that was recovered on the north half. However, the south half of the field was planted three days after the north half of the field, which accounts for the 8% reduction in yield and the 15% reduction in nitrogen uptake on the south half of the field. Surprisingly, the estimated marketable yields for the north and south halves of the field were measured to be 3,675 kg/ha and 5,260 kg/ha, respectively, by personnel from the University of Florida Research Center located in Live Oak, FL. The marketable yield was 1,585 kg/ha higher on the south half of th e field because lenticels developed on some of the north half potatoes. The lenticels developed because of the wetter soil conditions due to the additional 7.1 cm of irrigation applied to the north half of the field. The nitrogen recovery was about the same in 2002 for both halves of the field with each being approximately 42% of what was applied, but there was 24.5 kg/ha more nitrogen fertilizer available for leaching on the north half of the field. This indicates that the south half practices were effective in reducing the nitrate-nitrogen leaching at the project site. These results also show that careful irrigation and fertilizer management is critical to increase nitrogen recovery and reduce leaching. Irrigation scheduling should be based the crop status and environmental conditions in order to determine the amount of supplemental water needed to meet the crops water requirement. Further

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110 investigations need to be conducted for different fertilizer management scenarios primarily consisting of fertilizer application timing, placement, and type. The most logical approach to evaluate these different BMP scenarios is to implement the calibrated modified DSSAT model once it has been properly validated using an independent data set. The current DSSAT model does not adequately represent the potato crop system at the project site. From 2001 potato crop simulation comparisons for the original and modified computer models, it is apparent that the original algorithms used by DSSAT are not sufficient to simulate the soil-water and nitrate-nitrogen movement or crop growth for potatoes grown on beds in Florida. As shown in the 2001 model results (Chapter 3), while the model accurately predicted the soil moisture contents it did not accurately predict the total volume of water leached. It was clear after examining the nitratenitrogen concentrations and dry tuber yield results that the model significantly over predicted the volume of water drained out of the top 90 cm, which directly affects the nitrate-nitrogen leaching. As a result, the computer model underestimated the plant nitrogen uptake. Thus, the original model predicted the final crop yield to be 3,735 kg/ha while the actual yield was measured to be 6,840 kg/ha. The soil moisture content results for the original and modified models illustrate the difficulties in calibrating the DSSAT water bala nce. Increasing the CN from 75 to 95 had negligible effects on the accuracy of the moisture content predictions, which shows the insensitivity of the soil moisture content to changes in the volume of water infiltrating into the soil surface. This is mostly likely due to the physical characteristics of the sandy soils located at the project site. The soils at the research site tend to drain to field

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111 capacity relatively quickly, which makes it difficult to determine the accuracy of the drainage volume predictions made by the model. Given that most of the soil samples were taken when the soil had already drained to field capacity, it was uncertain whether or not the model predictions were accurate. Thus, the only way to determine if the water balance is correct is to take soil samples periodically immediately following a large rainfall event in order to measure transient infiltration rates and moisture contents. The modifications in the original DSSAT model significantly improved the models ability to predict nitrate-nitrogen transport, nitrogen uptake, and crop growth. In 2001, the modified CN, which was used to account for plant canopy and bed slope effects on infiltration, increased the original model prediction of 0.0 cm runoff to 4.9 cm, which reduced the rate that nitrate-nitrogen was leached out of the soil profile. The reduced bed width and doubled nitrogen fertilizer application rates used to concentrate the nitrogen fertilizer in the bed caused the nitrate-nitrogen concentration predictions to be three to six times larger than the original DSSAT predicted values. Also, the higher nitrate-nitrogen concentrations and reduced infiltration caused the 2001 nitrogen uptake predictions to improve from 58.4-kg/ha to 115-kg/ha, which is much closer to the measured value of 101.7-kg/ha. The predictions for crop growth greatly improved from 3,735-kg/ha to 6,924-kg/ha, which compares relatively well to the measured value of 6,840-kg/ha. The calibration results for the 2001 and 2002 crops show that currently the modified DSSAT model adequately predicts the 2001 and 2002 data. However, data from the 2003 potato crop now need to be simulated to validate the modified computer model. Once the model is validated, several different BMP scenarios can be evaluated in order to determined their effects on n itrate-nitrogen leaching and plant growth.

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112 After examining the water and solute transport algorithms used by the DSSAT crop model and the HYDRUS vadose zone model, it is obvious that a combination of the two models would be extremely beneficial. Co mbining both models would be beneficial because both models have relative advantages over each other. DSSAT simulates plant growth and estimates nutrient uptake, water uptake, and plant growth well, but the drained water volume is difficult to predict fo r sandy soils because of the simplified water balance. HYDRUS is a two-dimensional model that uses physically based equations to determine the nutrient and water transport in the soil and can properly represent systems with irregular shaped boundaries. Two-dimensional modeling is essential when attempting to represent physical systems with irregular boundaries. However, HYDRUS has a very limited plant model that does a relatively poor job of determining the plants ability to take up nutrients and soil-water. Thus, using the crop growth methods used by DSSAT and the water and solute transport methods used by HYDRUS would result in a more accurate representation of the potato crop system. If both models are combined, the new model could more accurately represent the potato crop system, specifically fertilizer placem ent effects. However, the methods used to determine potential evapotranspiration used in DSSAT need to be replaced with a more widely accepted method, such as the Penman-Monteith equation. Also, since neither model takes into account the runoff from the beds into the furrows, runoff should be routed using either the kinematic wave equation or dynamic wave equation. Further examination of effective rainfall and irrigation must be conducted in order to take into account the spatial variability between water infiltrating in the bed and in the furrow due to the plant canopy.

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113 Regarding the future research at the project site, several improvements can be made in the sampling methodologies that were used during the 2001 and 2002 potato crop growing seasons. During the 2001 and 2002 growing season, plant samples were taken randomly over the entire field generally close to the monitoring wells. After the 2002 season, it was obvious that the techniques used to collect the plant samples could be improved upon by increasing the number of plant samples taken over the season and implementing GIS software. More plant samples are needed in addition to the samples specified by the DSSAT documentation in order to obtain better representation of the crop growth and nitrogen uptake over the plant growing season. The increased plant sampling should consist of 16 or more samples taken during each sampling session with the number of samples divided evenly for each quadrant. Also, the plant samples should be taken more frequently, ideally once a week, in order to obtain better information regarding plant growth and nitrogen uptake. The GIS software should be implemented in order to account the variations in crop growth over the field. It takes the farmer approximately 10 to 14 days to plant the potato crop on the 56.7-ha field, which results in significant differences in crop growth over the field depending on the rows sampled. Thus, using a GPS unit to mark the plant sample locations would provide valuable insight on the spatial variability of plant growth. GIS could also be used to examine the variability in the nitrogen transport over the field as well. Given the results from this study, it is obvious that more research needs to be conducted at the project site in order to further evaluate different BMP scenarios and their effects on nitrate-nitrogen leaching. The data should be used to further determine the

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114 accuracy of the modified DSSAT model. Also, the modeling should be expanded from modeling the collected data only to performing risk assessments in relation to different weather years.

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APPENDIX A SOIL SAMPLE ANALYSIS RESULTS

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116 Table A-1. Soil sample results at the project site. Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/02/01 0 15 8 r n 29.33 27.73 5.46 8.25 17.2 316.2 4185.5 39.1 518.0 03/02/01 15 30 8 r n 29.2 27.63 5.38 8.47 71.9 1337.5 920.4 169.9 116.9 03/02/01 30 60 8 r n 29.37 27.68 5.75 9.10 4.5 78.9 118.9 21.5 32.4 03/02/01 0 15 9 r n 29.53 28.02 5.11 7.71 68.7 1342.8 3770.2 155.2 435.8 03/02/01 15 30 9 r n 29.7 26.25 11.62 19.58 20.0 171.8 120.1 50.5 35.3 03/02/01 60 90 9 r n 29.23 27.5 5.92 9.37 5.7 96.8 190.6 27.2 53.6 03/02/01 0 15 10 r n 29.02 27.37 5.69 8.62 7.2 127.4 159.4 16.5 20.6 03/02/01 15 30 10 r n 29.48 28.03 4.92 7.71 16.2 328.6 301.6 38.0 34.9 03/02/01 30 60 10 r n 29.82 28.52 4.36 6.79 16.7 383.2 197.7 78.1 40.3 03/02/01 60 90 10 r n 29.1 27.62 5.09 7.98 12.9 254.0 73.3 60.8 17.6 03/02/01 0 15 11 r n 29.44 27.37 7.03 10.82 19.4 276.1 457.4 44.8 74.2 03/02/01 15 30 11 r n 29.69 27.92 5.96 9.45 9.0 150.5 55.1 21.3 7.8 03/02/01 30 60 11 r n 29.38 27.71 5.68 8.98 14.5 255.8 307.9 68.9 82.9 03/02/01 60 90 11 r n 29.16 26.34 9.67 15.95 6.0 62.0 107.5 29.7 51.4 03/02/01 0 15 12 r s 29.14 28 3.91 5.82 23.2 593.0 560.9 51.8 49.0 03/02/01 15 30 12 r s 29.43 27.95 5.03 7.89 15.6 310.7 83.0 36.8 9.8 03/02/01 30 60 12 r s 29.45 28.22 4.18 6.49 14.5 348.1 238.2 67.8 46.4 03/02/01 60 90 12 r s 29.03 27.66 4.72 7.38 12.4 262.2 69.6 58.1 15.4 03/02/01 0 15 13 r s 29.11 27.48 5.60 8.48 31.9 569.0 4395.0 72.4 559.2 03/02/01 15 30 13 r s 29.19 27.49 5.82 9.21 48.1 825.9 865.0 114.1 119.6 03/02/01 30 60 13 r s 29.81 28.1 5.74 9.07 3.6 63.1 80.5 17.2 21.9 03/02/01 60 90 13 r s 29.35 27.82 5.21 8.19 3.3 64.2 20.4 15.8 5.0 03/02/01 0 15 3 r n 29.14 27.36 6.11 9.30 27.5 450.7 1329.4 62.9 185.5 03/02/01 15 30 3 r n 29.25 27.6 5.64 8.91 57.8 1025.3 1030.0 137.0 137.6 03/02/01 30 60 3 r n 29.11 27.48 5.60 8.84 25.4 453.0 145.9 120.1 38.7 03/02/01 60 90 3 r n 29.87 28.21 5.56 8.77 6.2 110.9 59.1 29.2 15.6 03/02/01 0 15 4 r s 29.67 28.19 4.99 7.51 41.6 834.0 956.5 93.9 107.7 03/02/01 15 30 4 r s 29.35 27.93 4.84 7.58 23.2 479.5 224.0 54.5 25.5 03/02/01 30 60 4 r s 29.27 27.63 5.60 8.84 4.7 83.9 58.6 22.3 15.6 03/02/01 60 90 4 r s 29.75 28.39 4.57 7.14 5.7 125.3 246.8 26.8 52.8 03/02/01 0 15 6 r s 29.06 27.13 6.64 10.17 45.4 683.5 4307.5 104.3 657.3 03/02/01 15 30 6 r s 29.43 28.02 4.79 7.50 23.2 484.2 105.7 54.5 11.9 03/02/01 30 60 6 r s 29.64 28.01 5.50 8.67 20.0 362.8 641.4 94.4 166.8 03/02/01 60 90 6 r s 29.26 27.86 4.78 7.49 5.8 122.0 59.4 27.4 13.3 03/02/01 0 15 7 r s 29.13 27.64 5.12 7.71 18.9 368.9 6374.6 42.7 737.1 03/02/01 15 30 7 r s 29.16 27.79 4.70 7.35 41.6 885.5 712.9 97.6 78.6 03/02/01 30 60 7 r s 29.11 27.62 5.12 8.04 4.2 82.3 255.1 19.9 61.5 03/02/01 60 90 7 r s 29.15 27.64 5.18 8.14 3.9 76.1 46.3 18.6 11.3 03/06/01 0 15 8 r n 29.04 27.8 4.27 6.38 17.2 402.9 201.8 38.5 19.3 03/06/01 15 30 8 r n 29.16 27.47 5.80 9.17 17.2 296.8 102.7 40.8 14.1 03/06/01 30 60 8 r n 29.01 27.33 5.79 9.16 7.4 127.8 49.1 35.1 13.5 03/06/01 60 90 8 r n 28.99 27.24 6.04 9.57 2.9 47.3 25.0 13.6 7.2 03/06/01 0 15 9 r n 29.06 27.79 4.37 6.54 15.5 354.6 400.5 34.8 39.3 03/06/01 15 30 9 r n 29.15 27.54 5.52 8.71 4.2 76.4 107.7 10.0 14.1 03/06/01 30 60 9 r n 29.11 27.73 4.74 7.42 3.0 62.6 88.0 13.9 19.6 03/06/01 60 90 9 r n 29.07 27.52 5.33 8.39 2.8 52.5 28.3 13.2 7.1 03/06/01 0 15 10 r n 29.04 27.73 4.51 6.76 18.9 419.1 1485.0 42.5 150.5 03/06/01 15 30 10 r n 29.09 27.47 5.57 8.79 35.4 635.2 338.2 83.7 44.6 03/06/01 30 60 10 r n 29.1 27.47 5.60 8.84 9.4 168.6 122.1 44.7 32.4 03/06/01 60 90 10 r n 29.12 27.51 5.53 8.72 5.2 94.8 27.3 24.8 7.1 03/06/01 0 15 11 r n 29.09 27.66 4.92 7.39 26.3 534.7 545.8 59.3 60.5 03/06/01 15 30 11 r n 29.04 27.32 5.92 9.38 26.3 443.8 415.5 62.5 58.5 03/06/01 30 60 11 r n 29.01 27.08 6.65 10.62 4.7 70.2 29.4 22.4 9.4 03/06/01 60 90 11 r n 29.03 27.02 6.92 11.08 8.6 124.9 15.4 41.5 5.1 03/06/01 0 15 12 r s 29.12 27.65 5.05 7.60 52.4 1038.1 1784.7 118.4 203.5 03/06/01 15 30 12 r s 29.12 27.65 5.05 7.92 44.5 880.7 513.9 104.6 61.1 03/06/01 30 60 12 r s 29.02 27.66 4.69 7.33 4.4 93.7 70.1 20.6 15.4 03/06/01 60 90 12 r s 29.06 27.53 5.26 8.28 4.8 90.9 11.8 22.6 2.9 03/06/01 0 15 3 r n 29.15 27.69 5.01 7.54 29.7 592.9 411.5 67.1 46.5

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117 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/02/01 15 30 3 r n 29.25 27.6 5.64 8.91 57.8 1025.3 1030.0 137.0 137.6 03/02/01 30 60 3 r n 29.11 27.48 5.60 8.84 25.4 453.0 145.9 120.1 38.7 03/02/01 60 90 3 r n 29.87 28.21 5.56 8.77 6.2 110.9 59.1 29.2 15.6 03/02/01 0 15 4 r s 29.67 28.19 4.99 7.51 41.6 834.0 956.5 93.9 107.7 03/02/01 15 30 4 r s 29.35 27.93 4.84 7.58 23.2 479.5 224.0 54.5 25.5 03/02/01 30 60 4 r s 29.27 27.63 5.60 8.84 4.7 83.9 58.6 22.3 15.6 03/02/01 60 90 4 r s 29.75 28.39 4.57 7.14 5.7 125.3 246.8 26.8 52.8 03/02/01 0 15 6 r s 29.06 27.13 6.64 10.17 45.4 683.5 4307.5 104.3 657.3 03/02/01 15 30 6 r s 29.43 28.02 4.79 7.50 23.2 484.2 105.7 54.5 11.9 03/02/01 30 60 6 r s 29.64 28.01 5.50 8.67 20.0 362.8 641.4 94.4 166.8 03/02/01 60 90 6 r s 29.26 27.86 4.78 7.49 5.8 122.0 59.4 27.4 13.3 03/02/01 0 15 7 r s 29.13 27.64 5.12 7.71 18.9 368.9 6374.6 42.7 737.1 03/02/01 15 30 7 r s 29.16 27.79 4.70 7.35 41.6 885.5 712.9 97.6 78.6 03/02/01 30 60 7 r s 29.11 27.62 5.12 8.04 4.2 82.3 255.1 19.9 61.5 03/02/01 60 90 7 r s 29.15 27.64 5.18 8.14 3.9 76.1 46.3 18.6 11.3 03/06/01 0 15 8 r n 29.04 27.8 4.27 6.38 17.2 402.9 201.8 38.5 19.3 03/06/01 15 30 8 r n 29.16 27.47 5.80 9.17 17.2 296.8 102.7 40.8 14.1 03/06/01 30 60 8 r n 29.01 27.33 5.79 9.16 7.4 127.8 49.1 35.1 13.5 03/06/01 60 90 8 r n 28.99 27.24 6.04 9.57 2.9 47.3 25.0 13.6 7.2 03/06/01 0 15 9 r n 29.06 27.79 4.37 6.54 15.5 354.6 400.5 34.8 39.3 03/06/01 15 30 9 r n 29.15 27.54 5.52 8.71 4.2 76.4 107.7 10.0 14.1 03/06/01 30 60 9 r n 29.11 27.73 4.74 7.42 3.0 62.6 88.0 13.9 19.6 03/06/01 60 90 9 r n 29.07 27.52 5.33 8.39 2.8 52.5 28.3 13.2 7.1 03/06/01 0 15 10 r n 29.04 27.73 4.51 6.76 18.9 419.1 1485.0 42.5 150.5 03/06/01 15 30 10 r n 29.09 27.47 5.57 8.79 35.4 635.2 338.2 83.7 44.6 03/06/01 30 60 10 r n 29.1 27.47 5.60 8.84 9.4 168.6 122.1 44.7 32.4 03/06/01 60 90 10 r n 29.12 27.51 5.53 8.72 5.2 94.8 27.3 24.8 7.1 03/06/01 0 15 11 r n 29.09 27.66 4.92 7.39 26.3 534.7 545.8 59.3 60.5 03/06/01 15 30 11 r n 29.04 27.32 5.92 9.38 26.3 443.8 415.5 62.5 58.5 03/06/01 30 60 11 r n 29.01 27.08 6.65 10.62 4.7 70.2 29.4 22.4 9.4 03/06/01 60 90 11 r n 29.03 27.02 6.92 11.08 8.6 124.9 15.4 41.5 5.1 03/06/01 0 15 12 r s 29.12 27.65 5.05 7.60 52.4 1038.1 1784.7 118.4 203.5 03/06/01 15 30 12 r s 29.12 27.65 5.05 7.92 44.5 880.7 513.9 104.6 61.1 03/06/01 30 60 12 r s 29.02 27.66 4.69 7.33 4.4 93.7 70.1 20.6 15.4 03/06/01 60 90 12 r s 29.06 27.53 5.26 8.28 4.8 90.9 11.8 22.6 2.9 03/06/01 0 15 3 r n 29.15 27.69 5.01 7.54 29.7 592.9 411.5 67.1 46.5 03/06/01 15 30 3 r n 29.1 27.38 5.91 9.36 16.1 271.8 506.6 38.2 71.1 03/06/01 30 60 3 r n 29.07 27.36 5.88 9.31 24.0 408.3 237.1 114.1 66.2 03/06/01 60 90 3 r n 29.01 27.25 6.07 9.62 11.0 180.6 24.9 52.1 7.2 03/06/01 0 15 4 r s 29.04 27.63 4.86 7.30 11.0 225.7 21.9 24.7 2.4 03/06/01 15 30 4 r s 29.1 27.5 5.50 8.67 7.4 134.6 609.2 17.5 79.2 03/06/01 30 60 4 r s 29.07 27.37 5.85 9.25 12.1 206.8 519.6 57.4 144.3 03/06/01 60 90 4 r s 29.01 27.23 6.14 9.74 1.9 30.8 24.6 9.0 7.2 03/07/01 0 15 6 r s 28.9 27.58 4.57 6.84 18.3 401.5 1758.5 41.2 180.5 03/07/01 30 60 6 r s 29.08 27.54 5.30 8.33 3.4 64.6 137.5 16.2 34.4 03/07/01 60 90 6 r s 29 27.44 5.38 8.47 2.3 42.5 11.5 10.8 2.9 03/07/01 15 30 7 r s 29.36 27.93 4.87 7.63 7.5 155.0 158.7 17.7 18.2 03/24/01 0 15 8 r n 29.08 27.29 6.16 9.38 4.2 68.6 1319.3 9.7 185.6 03/24/01 15 30 8 r n 29.05 27.24 6.23 9.90 43.4 696.3 1488.7 103.4 221.1 03/24/01 30 60 8 r n 29.09 27.21 6.46 10.29 52.0 805.0 312.1 248.6 96.4 03/24/01 60 90 8 r n 29.02 27.23 6.17 9.79 9.1 147.9 24.5 43.5 7.2 03/24/01 0 15 9 r n 29.02 27.61 4.86 7.30 3.5 72.7 85.9 8.0 9.4 03/24/01 15 30 9 r n 29.05 27.61 4.96 7.77 14.6 293.9 693.6 34.3 80.9 03/24/01 30 60 9 r n 29.13 27.6 5.25 8.26 19.8 376.2 400.9 93.2 99.3 03/24/01 60 90 9 r n 29.14 27.64 5.15 8.09 13.4 260.7 37.9 63.2 9.2 03/24/01 0 15 10 r n 29.02 27.41 5.55 8.40 8.9 161.3 19.2 20.3 2.4 03/24/01 15 30 10 r n 29.15 27.48 5.73 9.05 21.5 375.0 34.1 50.9 4.6 03/24/01 30 60 10 r n 29.26 27.62 5.60 8.85 18.0 321.6 58.6 85.4 15.6 03/24/01 60 90 10 r n 29.01 27.36 5.69 8.99 6.2 108.7 26.5 29.3 7.1

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118 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/24/01 0 15 11 r n 29.1 27.5 5.50 8.32 7.9 143.9 738.5 18.0 92.2 03/24/01 15 30 11 r n 29.07 27.34 5.95 9.43 28.4 477.2 391.1 67.5 55.3 03/24/01 30 60 11 r n 29.1 27.37 5.95 9.42 16.9 283.9 130.0 80.2 36.7 03/24/01 60 90 11 r n 29.17 27.46 5.86 9.28 18.0 307.5 33.3 85.6 9.3 03/24/01 0 15 12 r s 29.2 27.9 4.45 6.66 22.1 495.5 832.2 49.5 83.2 03/24/01 15 30 12 r s 29.17 27.69 5.07 7.96 34.2 673.3 169.8 80.4 20.3 03/24/01 30 60 12 r s 28.99 27.41 5.45 8.59 23.8 436.5 158.1 112.5 40.7 03/24/01 60 90 12 r s 29.26 27.76 5.13 8.05 22.6 441.6 46.8 106.7 11.3 03/24/01 0 15 13 r s 29.4 27.03 8.06 12.54 8.7 107.4 128.9 20.2 24.2 03/24/01 15 30 13 r s 29.41 27.62 6.09 9.66 34.7 570.8 83.2 82.7 12.0 03/24/01 30 60 13 r s 29.17 27.42 6.00 9.51 16.9 281.3 25.1 80.2 7.2 03/24/01 60 90 13 r s 29.25 27.58 5.71 9.02 8.5 148.7 73.1 40.2 19.8 03/24/01 0 15 3 r n 29.07 26.93 7.36 11.36 28.4 385.8 382.6 65.8 65.2 03/24/01 15 30 3 r n 29.11 27.32 6.15 9.76 84.9 1380.3 1262.8 202.1 184.9 03/24/01 30 60 3 r n 29.06 27.27 6.16 9.78 52.6 854.0 168.7 250.6 49.5 03/24/01 60 90 3 r n 29.31 27.45 6.35 10.10 24.9 393.1 30.8 119.1 9.3 03/24/01 0 15 4 r s 29.28 27.74 5.26 7.94 2.7 51.8 28.7 6.2 3.4 03/24/01 15 30 4 r s 29.09 27.76 4.57 7.14 2.0 44.5 246.8 4.8 26.4 03/24/01 30 60 4 r s 29.13 27.59 5.29 8.32 3.4 63.5 230.2 15.9 57.4 03/24/01 60 90 4 r s 29.04 27.5 5.30 8.34 3.6 68.8 62.0 17.2 15.5 03/24/01 0 15 6 r s 29.29 27.8 5.09 7.66 61.2 1204.0 588.6 138.4 67.7 03/24/01 0 15 7 r s 29.17 27.68 5.11 7.70 4.5 87.2 1328.9 10.1 153.4 03/24/01 15 30 7 r s 29.26 27.57 5.78 9.13 58.4 1010.5 803.0 138.4 110.0 03/24/01 30 60 7 r s 29.74 28.08 5.58 8.81 18.0 323.0 480.7 85.3 127.0 03/24/01 60 90 7 r s 28.94 27.26 5.81 9.18 18.6 320.5 270.9 88.3 74.6 03/24/01 15 30 7 r s 29.15 27.63 5.21 8.20 22.1 423.1 454.9 52.0 55.9 03/24/01 30 60 7 r s 29.5 27.85 5.59 8.83 54.9 981.7 138.2 260.0 36.6 03/24/01 60 90 7 r s 29.25 27.68 5.37 8.45 7.5 139.9 77.8 35.5 19.7 04/03/01 0 15 8 r n 29.04 27.68 4.68 7.03 7.6 163.0 961.9 17.2 101.4 04/03/01 15 30 8 r n 29.38 27.82 5.31 8.36 9.5 178.5 61.9 22.4 7.8 04/03/01 30 60 8 r n 28.91 27.28 5.64 8.90 11.2 197.8 34.6 52.8 9.3 04/03/01 60 90 8 r n 29.68 28.04 5.53 8.71 13.5 243.6 11.2 63.7 2.9 04/03/01 0 15 9 r n 29.67 28.46 4.08 6.08 4.6 113.6 320.2 10.4 29.2 04/03/01 15 30 9 r n 29.35 28.08 4.33 6.74 14.0 324.4 979.4 32.8 99.0 04/03/01 30 60 9 r n 29.34 27.72 5.52 8.71 15.2 275.2 397.4 71.9 103.8 04/03/01 60 90 9 r n 29.35 27.91 4.91 7.69 38.3 779.9 302.4 179.9 69.7 04/03/01 0 15 10 r n 29.51 28.28 4.17 6.22 6.8 162.4 292.0 15.1 27.2 04/03/01 15 30 10 r n 29.58 28.01 5.31 8.35 18.1 340.6 112.1 42.7 14.0 04/03/01 30 60 10 r n 29.17 27.61 5.35 8.42 8.1 151.4 443.6 38.2 112.0 04/03/01 60 90 10 r n 29.15 27.68 5.04 7.91 48.1 953.2 47.5 226.3 11.3 04/03/01 0 15 11 r n 29.15 27.64 5.18 7.81 29.0 560.5 1670.6 65.7 195.8 04/03/01 15 30 11 r n 29.82 28.28 5.16 8.11 51.5 997.8 958.3 121.4 116.6 04/03/01 30 60 11 r n 29.29 27.6 5.77 9.12 34.8 603.2 133.9 165.1 36.7 04/03/01 60 90 11 r n 29.75 27.18 8.64 14.09 29.0 336.1 58.6 142.1 24.8 04/03/01 0 15 12 r s 29.49 28.21 4.34 6.49 2.2 50.9 55.2 5.0 5.4 04/03/01 15 30 12 r s 29.21 28.2 3.46 5.34 14.6 422.7 69.3 33.8 5.5 04/03/01 30 60 12 r s 29.04 27.5 5.30 8.34 40.6 765.0 355.2 191.5 88.9 04/03/01 60 90 12 r s 29.43 27.89 5.23 8.23 70.0 1337.5 249.6 330.1 61.6 04/03/01 0 15 13 r s 28.97 26.83 7.39 11.41 5.8 78.3 62.5 13.4 10.7 04/03/01 15 30 13 r s 29.01 27.67 4.62 7.22 10.0 216.5 523.2 23.4 56.6 04/03/01 30 60 13 r s 29.83 28.19 5.50 8.67 29.0 528.1 67.8 137.3 17.6 04/03/01 60 90 13 r s 29.98 28.31 5.57 8.79 21.5 386.6 43.0 101.9 11.3 04/03/01 0 15 3 r n 29.52 27.75 6.00 9.12 10.6 176.4 817.9 24.1 111.9 04/03/01 15 30 3 r n 29.43 27.74 5.74 9.08 26.2 455.4 312.5 62.0 42.6 04/03/01 30 60 3 r n 29.84 27.87 6.60 10.53 40.6 614.5 56.5 194.2 17.9 04/03/01 60 90 3 r n 29.45 27.57 6.38 10.16 26.2 409.7 37.5 124.9 11.4 04/03/01 0 15 4 r s 29.73 27.89 6.19 9.43 21.5 348.0 60.3 49.2 8.5 04/03/01 15 30 4 r s 29.43 27.83 5.44 8.57 38.3 703.8 191.2 90.4 24.6 04/03/01 30 60 4 r s 29.06 27.5 5.37 8.45 69.4 1293.0 61.2 327.9 15.5

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119 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 04/03/01 60 90 4 r s 29.35 27.72 5.55 8.76 29.0 522.8 19.2 137.4 5.0 04/03/01 0 15 6 r s 29.37 28.81 1.91 2.78 5.6 294.5 498.5 12.3 20.8 04/03/01 15 30 6 r s 29.76 28.28 4.97 7.80 40.6 815.8 1490.0 95.4 174.3 04/03/01 30 60 6 r s 29.38 28.01 4.66 7.29 27.3 585.6 480.1 128.0 105.0 04/03/01 60 90 6 r s 29.86 28.2 5.56 8.77 7.7 138.3 83.1 36.4 21.9 04/03/01 0 15 7 r s 29.1 28.31 2.71 3.99 6.7 247.2 7101.4 14.8 425.1 04/03/01 15 30 7 r s 29.72 28.7 3.43 5.30 26.2 762.0 264.0 60.5 21.0 04/03/01 30 60 7 r s 29.5 27.9 5.42 8.54 12.9 237.6 85.1 60.9 21.8 04/03/01 60 90 7 r s 29.08 27.5 5.43 8.56 13.5 247.8 44.1 63.6 11.3 04/20/01 0 15 8 r n 29.48 27.67 6.14 9.35 0.9 14.2 116.7 2.0 16.4 04/20/01 15 30 8 r n 29.04 27.18 6.40 10.20 0.8 11.8 44.5 1.8 6.8 04/20/01 30 60 8 r n 29.23 27.47 6.02 9.55 0.5 8.8 37.1 2.5 10.6 04/20/01 60 90 8 r n 29.56 27.93 5.51 8.70 0.9 15.8 40.5 4.1 10.6 04/20/01 0 15 9 r n 29.69 28.15 5.19 7.82 24.0 462.1 90.6 54.2 10.6 04/20/01 15 30 9 r n 29.24 27.75 5.10 8.00 13.2 259.5 152.7 31.1 18.3 04/20/01 30 60 9 r n 29.37 27.83 5.24 8.25 8.8 168.7 54.4 41.7 13.4 04/20/01 60 90 9 r n 29.42 27.96 4.96 7.78 9.0 180.5 57.4 42.1 13.4 04/20/01 0 15 10 r n 29.1 26.94 7.42 11.47 1.8 23.9 38.4 4.1 6.6 04/20/01 15 30 10 r n 29.38 27.56 6.19 9.84 5.0 80.7 75.9 11.9 11.2 04/20/01 30 60 10 r n 29.78 28.05 5.81 9.19 1.5 25.7 80.9 7.1 22.3 04/20/01 60 90 10 r n 29.11 27.45 5.70 9.01 3.1 53.9 50.0 14.6 13.5 04/20/01 0 15 11 r n 29.31 27.15 7.37 11.38 1.9 25.6 72.1 4.4 12.3 04/20/01 15 30 11 r n 29.38 27.57 6.16 9.78 9.7 157.3 186.3 23.1 27.3 04/20/01 30 60 11 r n 28.98 27.08 6.56 10.45 1.0 15.9 306.7 5.0 96.2 04/20/01 60 90 11 r n 29.48 27.8 5.70 9.00 1.4 25.2 114.9 6.8 31.0 04/20/01 0 15 12 r s 29.76 28.2 5.24 7.91 1.3 24.1 54.4 2.9 6.5 04/20/01 15 30 12 r s 29 27.51 5.14 8.07 1.0 19.1 43.5 2.3 5.3 04/20/01 30 60 12 r s 29.37 27.91 4.97 7.79 2.1 42.5 44.9 9.9 10.5 04/20/01 60 90 12 r s 29.85 28.23 5.43 8.55 1.9 34.8 41.2 8.9 10.6 04/20/01 0 15 13 r s 29.23 27 7.63 11.81 1.2 15.1 37.4 2.7 6.6 04/20/01 15 30 13 r s 29.22 27.32 6.50 10.36 0.5 7.3 24.9 1.1 3.9 04/20/01 30 60 13 r s 29.18 27.54 5.62 8.87 1.4 24.5 61.7 6.5 16.4 04/20/01 60 90 13 r s 29.21 27.52 5.79 9.15 0.9 16.0 49.3 4.4 13.5 04/20/01 0 15 3 r n 29.15 26.8 8.06 12.54 1.2 15.0 65.9 2.8 12.4 04/20/01 15 30 3 r n 29.31327.33 6.76 10.81 0.6 9.5 42.1 1.5 6.8 04/20/01 30 60 3 r n 29.96 28.14 6.07 9.64 0.4 5.9 67.2 1.7 19.4 04/20/01 60 90 3 r n 29.06 27.44 5.57 8.80 0.6 10.5 51.1 2.8 13.5 04/20/01 0 15 4 r s 29.39 27.54 6.29 9.61 0.8 12.9 45.3 1.9 6.5 04/20/01 15 30 4 r s 29.07 27.26 6.23 9.89 0.5 8.5 45.8 1.3 6.8 04/20/01 30 60 4 r s 29.28 27.63 5.64 8.90 0.2 4.4 50.6 1.2 13.5 04/20/01 60 90 4 r s 29.87 28.09 5.96 9.44 0.4 6.1 47.8 1.7 13.5 04/20/01 0 15 6 r s 29.04 27.32 5.92 9.00 2.5 42.4 58.5 5.7 7.9 04/20/01 15 30 6 r s 29.37 27.86 5.14 8.08 6.1 119.2 55.4 14.4 6.7 04/20/01 30 60 6 r s 29.28 27.77 5.16 8.10 1.6 31.1 31.4 7.6 7.6 04/20/01 60 90 6 r s 29.13 27.61 5.22 8.20 5.0 95.8 31.0 23.6 7.6 04/20/01 0 15 7 r s 29.13 27.12 6.90 10.60 1.1 15.9 41.3 2.5 6.6 04/20/01 15 30 7 r s 29.02 27.22 6.20 9.85 0.5 8.5 36.0 1.3 5.3 04/20/01 30 60 7 r s 29.48 27.74 5.90 9.35 0.3 5.2 37.8 1.4 10.6 04/20/01 60 90 7 r s 29.93 28.3 5.45 8.58 0.9 17.0 41.0 4.4 10.6 05/04/01 0 15 8 r n 29.01 28.07 3.24 4.79 6.8 211.1 65.6 15.2 4.7 05/04/01 15 30 8 r n 29.02 27.76 4.34 6.76 48.0 1106.4 94.9 112.2 9.6 05/04/01 30 60 8 r n 29.89 28.16 5.79 9.15 32.9 568.8 170.6 156.2 46.8 05/04/01 60 90 8 r n 29.31 27.77 5.25 8.26 27.1 515.9 145.5 127.9 36.1 05/04/01 0 15 9 r n 29.15 27.67 5.08 7.65 2.4 47.7 45.3 5.5 5.2 05/04/01 15 30 9 r n 29.65 28.07 5.33 8.39 10.3 192.7 61.9 24.2 7.8 05/04/01 30 60 9 r n 29.21 27.67 5.27 8.29 2.0 38.2 100.4 9.5 25.0 05/04/01 60 90 9 r n 29.24 27.89 4.62 7.21 0.8 17.1 53.6 3.7 11.6 05/04/01 0 15 10 r n 29.07 28.17 3.10 4.57 2.8 91.3 78.1 6.3 5.4 05/04/01 15 30 10 r n 29.19 23.93 18.02 32.75 6.0 33.1 26.1 16.3 12.8

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120 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/04/01 30 60 10 r n 29.54 27.86 5.69 8.98 9.9 174.4 290.9 47.0 78.4 05/04/01 60 90 10 r n 29.13 27.43 5.84 9.23 11.4 195.5 96.8 54.1 26.8 05/04/01 0 15 11 r n 29.32 27.02 7.84 12.17 2.4 30.8 33.1 5.6 6.0 05/04/01 15 30 11 r n 29.65 28.61 3.51 5.42 1.5 42.5 219.6 3.5 17.8 05/04/01 30 60 11 r n 29.5 28.03 4.98 7.81 7.8 157.1 284.9 36.8 66.8 05/04/01 60 90 11 r n 29.28 27.75 5.23 8.22 4.0 76.4 82.2 18.8 20.3 05/04/01 0 15 12 r s 29.08 28.02 3.65 5.41 16.6 456.5 59.9 37.0 4.9 05/04/01 15 30 12 r s 29.78 28.93 2.85 4.38 17.8 623.7 99.1 41.0 6.5 05/04/01 30 60 12 r s 29.49 28.06 4.85 7.59 3.0 61.9 39.0 14.1 8.9 05/04/01 60 90 12 r s 29.36 27.83 5.21 8.19 1.3 24.1 48.6 5.9 12.0 05/04/01 0 15 13 r s 29.6 28.21 4.70 7.05 13.2 280.0 87.7 29.6 9.3 05/04/01 15 30 13 r s 29.11 27.58 5.26 8.27 38.2 725.9 103.0 90.0 12.8 05/04/01 30 60 13 r s 29.76 28.1 5.58 8.80 21.9 392.1 126.5 103.5 33.4 05/04/01 60 90 13 r s 29.49 28.02 4.98 7.82 22.5 450.5 101.5 105.6 23.8 05/04/01 0 15 3 r n 29.64 28.17 4.96 7.46 3.9 79.3 65.3 8.9 7.3 05/04/01 15 30 3 r n 29.06 27.7 4.68 7.32 0.5 10.7 64.2 1.2 7.0 05/04/01 30 60 3 r n 29.06 27.32 5.99 9.49 0.5 8.4 178.3 2.4 50.8 05/04/01 60 90 3 r n 29.49 27.87 5.49 8.66 0.6 10.2 109.2 2.6 28.4 05/04/01 0 15 4 r s 29.42 27.95 5.00 7.52 5.6 112.4 84.8 12.7 9.6 05/04/01 15 30 4 r s 29.35 27.93 4.84 7.58 0.6 11.6 74.2 1.3 8.4 05/04/01 30 60 4 r s 29.12 27.64 5.08 7.98 3.2 62.5 325.5 15.0 77.9 05/04/01 60 90 4 r s 29.04 27.35 5.82 9.21 1.3 21.6 125.3 6.0 34.6 05/04/01 0 15 6 r s 29.49 28.45 3.53 5.23 12.6 356.4 306.9 27.9 24.1 05/04/01 15 30 6 r s 29.14 27.8 4.60 7.18 41.6 905.5 359.8 97.6 38.8 05/04/01 30 60 6 r s 29.37 27.96 4.80 7.51 14.9 310.3 320.2 69.9 72.2 05/04/01 60 90 6 r s 29.16 27.75 4.84 7.57 13.7 284.0 165.3 64.5 37.6 05/04/01 0 15 7 r s 29.61 28.55 3.58 5.31 3.8 106.6 193.8 8.5 15.4 05/04/01 15 30 7 r s 29.57 28.24 4.50 7.02 7.9 176.6 68.1 18.6 7.2 05/04/01 30 60 7 r s 29.28 27.79 5.09 7.99 12.0 235.6 159.4 56.5 38.2 05/04/01 60 90 7 r s 29.08 27.57 5.19 8.16 21.3 410.0 329.9 100.4 80.8 05/25/01 0 15 8 r n 29.64 23.4 21.05 38.13 3.5 16.5 41.3 9.4 23.6 05/25/01 15 30 8 r n 29.46 23.58 19.96 37.16 15.3 76.7 36.2 42.8 20.2 05/25/01 30 60 8 r n 29.43 24.58 16.48 29.40 1.1 6.5 24.6 5.8 21.7 05/25/01 60 90 8 r n 29.63 28.19 4.86 7.61 11.9 243.9 64.2 55.7 14.7 05/25/01 0 15 9 r n 29.91 28.52 4.65 6.97 4.4 94.4 69.7 9.9 7.3 05/25/01 15 30 9 r n 29.05 23.46 19.24 35.50 6.1 31.7 18.7 16.9 9.9 05/25/01 30 60 9 r n 29.38 27.91 5.00 7.85 4.7 93.4 354.2 22.0 83.4 05/25/01 60 90 9 r n 29.1 27.49 5.53 8.73 2.0 37.0 95.7 9.7 25.1 05/25/01 0 15 10 r n 29.72 23.34 21.47 39.09 2.5 11.7 28.8 6.8 16.9 05/25/01 15 30 10 r n 29.4 28.32 3.67 5.68 22.7 618.9 115.4 52.8 9.8 05/25/01 30 60 10 r n 29.85 28.47 4.62 7.22 7.5 161.5 172.9 35.0 37.5 05/25/01 60 90 10 r n 29.6 24.6 16.89 30.28 1.6 9.4 15.4 8.5 14.0 05/25/01 0 15 11 r n 29.53 28.58 3.22 4.75 5.1 157.6 182.8 11.2 13.0 05/25/01 15 30 11 r n 29.27 28.08 4.07 6.31 5.9 144.4 101.3 13.7 9.6 05/25/01 30 60 11 r n 29.7 26.77 9.87 16.31 1.1 11.5 43.6 5.6 21.3 05/25/01 60 90 11 r n 29.14 27.51 5.59 8.83 2.5 44.7 82.1 11.8 21.7 05/25/01 0 15 12 r s 29.17 28.66 1.75 2.54 4.8 273.7 296.1 10.4 11.3 05/25/01 15 30 12 r s 29.11 28.07 3.57 5.52 29.0 812.1 97.3 67.3 8.1 05/25/01 30 60 12 r s 29.18 24.04 17.61 31.86 1.6 9.0 22.1 8.6 21.1 05/25/01 60 90 12 r s 29.42 26.19 10.98 18.38 57.0 519.0 31.1 286.1 17.2 05/25/01 0 15 13 r s 29.34 28.44 3.07 4.53 13.0 424.9 140.1 28.8 9.5 05/25/01 15 30 13 r s 29.24 27.78 4.99 7.83 19.3 386.8 119.0 45.4 14.0 05/25/01 30 60 13 r s 29.18 24.16 17.20 30.96 5.4 31.5 15.8 29.2 14.6 05/25/01 60 90 13 r s 29.44 28.1 4.55 7.11 6.2 135.2 91.8 28.8 19.6 05/25/01 0 15 3 r n 29.06 28.11 3.27 4.83 3.5 106.2 205.1 7.7 14.9 05/25/01 15 30 3 r n 29.45 27.98 4.99 7.83 4.8 97.0 101.4 11.4 11.9 05/25/01 30 60 3 r n 29.08 27.43 5.67 8.96 10.6 186.8 155.4 50.2 41.8 05/25/01 60 90 3 r n 29.8 28.21 5.34 8.40 6.5 121.8 64.0 30.7 16.1 05/25/01 0 15 4 r s 29.63 28.74 3.00 4.43 4.3 144.1 139.1 9.6 9.2

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121 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/25/01 15 30 4 r s 29.56 28.39 3.96 6.14 5.6 142.5 130.8 13.1 12.0 05/25/01 30 60 4 r s 29.78 27.9 6.31 10.04 4.4 70.4 42.9 21.2 12.9 05/25/01 60 90 4 r s 29.21 23.25 20.40 38.20 2.2 10.9 15.6 12.4 17.9 05/25/01 0 15 6 r s 29.03 28.6 1.48 2.15 8.8 596.6 305.9 19.2 9.9 05/25/01 15 30 6 r s 29.87 28.53 4.49 7.00 26.7 595.9 136.3 62.6 14.3 05/25/01 30 60 6 r s 29.15 27.82 4.56 7.12 7.2 158.7 154.6 33.9 33.0 05/25/01 60 90 6 r s 29.63 28.39 4.18 6.51 9.7 231.6 141.9 45.2 27.7 05/25/01 0 15 7 r s 29.55 28.88 2.27 3.32 3.5 153.1 114.4 7.6 5.7 05/25/01 15 30 7 r s 29.03 28 3.55 5.48 2.2 62.5 104.5 5.1 8.6 05/25/01 30 60 7 r s 29.27 27.96 4.48 6.98 6.6 146.4 55.3 30.7 11.6 05/25/01 60 90 7 r s 29.39 28.06 4.53 7.06 2.3 51.5 54.7 10.9 11.6 06/06/01 0 15 8 r n 29.13 27.51 5.56 8.42 13.6 245.2 162.8 31.0 20.6 06/06/01 15 30 8 r n 29.7 28.15 5.22 8.20 17.0 326.5 157.7 40.2 19.4 06/06/01 30 60 8 r n 29.82 27.8 6.77 10.83 10.2 151.0 52.2 49.0 16.9 06/06/01 60 90 8 r n 29.53 28.03 5.08 7.97 6.1 119.6 62.6 28.6 15.0 06/06/01 0 15 9 r n 29.26 27.8 4.99 7.51 6.4 127.5 157.9 14.4 17.8 06/06/01 15 30 9 r n 29.68 28.21 4.95 7.76 6.2 126.1 84.4 14.7 9.8 06/06/01 30 60 9 r n 29.43 27.85 5.37 8.45 3.0 55.0 110.6 14.0 28.1 06/06/01 60 90 9 r n 29.65 28.11 5.19 8.16 3.7 72.2 74.8 17.7 18.3 06/06/01 0 15 10 r n 29.45 28.38 3.63 5.39 34.1 938.0 139.3 75.9 11.3 06/06/01 15 30 10 r n 29.62 28.28 4.52 7.06 57.9 1280.6 339.8 135.6 36.0 06/06/01 30 60 10 r n 29.34 28.11 4.19 6.52 10.1 241.1 189.3 47.2 37.0 06/06/01 60 90 10 r n 29.64 24.54 17.21 30.97 6.6 38.3 37.9 35.6 35.2 06/06/01 0 15 11 r n 29.39 27.82 5.34 8.07 8.9 165.9 138.7 20.1 16.8 06/06/01 15 30 11 r n 29.29 27.86 4.88 7.65 41.5 849.3 196.2 97.4 22.5 06/06/01 30 60 11 r n 29.25 27.86 4.75 7.43 31.2 657.4 186.8 146.6 41.7 06/06/01 60 90 11 r n 29.39 27.93 4.97 7.79 27.3 548.8 129.0 128.2 30.1 06/06/01 0 15 12 r s 29.74 28.62 3.77 5.60 6.9 184.0 100.1 15.4 8.4 06/06/01 15 30 12 r s 29.43 28.2 4.18 6.50 60.2 1440.5 98.6 140.4 9.6 06/06/01 30 60 12 r s 29.41 27.92 5.07 7.95 13.9 273.5 57.0 65.3 13.6 06/06/01 60 90 12 r s 29.37 27.92 4.94 7.74 8.3 169.1 68.0 39.3 15.8 06/06/01 0 15 13 r s 29.27 27.8 5.02 7.56 9.1 180.9 98.4 20.5 11.2 06/06/01 15 30 13 r s 29.14 27.81 4.56 7.13 6.6 144.3 87.7 15.4 9.4 06/06/01 30 60 13 r s 29.68 28.39 4.35 6.77 9.0 206.5 75.9 41.9 15.4 06/06/01 60 90 13 r s 29.46 28.01 4.92 7.71 4.4 90.0 88.5 20.8 20.5 06/06/01 0 15 3 r n 29.43 27.97 4.96 7.46 16.5 332.1 144.6 37.2 16.2 06/06/01 15 30 3 r n 29.21 27.52 5.79 9.15 52.3 903.1 115.9 124.0 15.9 06/06/01 30 60 3 r n 29.47 27.57 6.45 10.27 14.2 220.3 149.5 67.9 46.1 06/06/01 60 90 3 r n 29.24 27.47 6.05 9.60 5.5 90.1 224.8 25.9 64.8 06/06/01 0 15 4 r s 29.44 28.08 4.62 6.93 9.8 211.5 157.8 22.0 16.4 06/06/01 15 30 4 r s 29.85 28.59 4.22 6.57 6.9 162.8 100.4 16.0 9.9 06/06/01 30 60 4 r s 29.61 27.85 5.94 9.42 5.3 88.9 63.4 25.1 17.9 06/06/01 60 90 4 r s 29.31 27.87 4.91 7.70 8.5 173.4 82.7 40.0 19.1 01/09/02 0 15 8 r n 29.57 28.08 5.04 7.59 7.1 140.3 85.8 16.0 9.8 01/09/02 15 30 8 r n 29.41 27.89 5.17 8.12 8.6 165.7 82.5 20.2 10.0 01/09/02 30 60 8 r n 29.15 27.55 5.49 8.65 3.9 71.5 56.2 18.6 14.6 01/09/02 60 90 8 r n 29.5 27.99 5.12 8.04 1.0 19.5 69.5 4.7 16.8 01/09/02 0 15 9 r n 29.4 27.94 4.97 7.47 3.3 67.3 69.2 7.5 7.8 01/09/02 15 30 9 r n 29.47 27.94 5.19 8.16 0.7 13.0 46.9 1.6 5.7 01/09/02 30 60 9 r n 29.78 28.25 5.14 8.07 1.3 25.6 101.3 6.2 24.5 01/09/02 60 90 9 r n 29.71 28.26 4.88 7.65 1.2 23.7 109.1 5.4 25.0 01/09/02 0 15 10 r n 29.73 27.98 5.89 8.94 2.3 39.5 69.4 5.3 9.3 01/09/02 15 30 10 r n 29.27 27.66 5.50 8.67 1.3 23.9 79.6 3.1 10.4 01/09/02 30 60 10 r n 29.31 27.76 5.29 8.32 4.1 77.3 51.6 19.3 12.9 01/09/02 60 90 10 r n 29.23 27.76 5.03 7.89 0.8 15.6 71.9 3.7 17.0 01/09/02 0 15 11 r n 29.27 27.66 5.50 8.32 2.4 43.3 124.6 5.4 15.6 01/09/02 15 30 11 r n 29.23 27.72 5.17 8.12 1.4 27.5 84.8 3.4 10.3 01/09/02 30 60 11 r n 29.43 27.87 5.30 8.34 1.2 22.8 57.1 5.7 14.3 01/09/02 60 90 11 r n 29.36 27.7 5.65 8.93 6.4 113.7 28.5 30.5 7.6

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122 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 01/09/02 0 15 12 r s 29.76 28.36 4.70 7.06 3.2 68.7 70.6 7.3 7.5 01/09/02 15 30 12 r s 29.69 28.01 5.66 8.94 2.2 38.3 26.4 5.1 3.5 01/09/02 30 60 12 r s 29.61 27.98 5.50 8.68 2.7 49.1 47.5 12.8 12.4 01/09/02 60 90 12 r s 29.46 27.9 5.30 8.33 1.5 28.9 34.9 7.2 8.7 01/09/02 0 15 13 r s 29.69 28.24 4.88 7.34 10.3 211.0 36.6 23.2 4.0 01/09/02 15 30 13 r s 29.43 27.82 5.47 8.62 6.4 117.6 93.0 15.2 12.0 01/09/02 30 60 13 r s 29.71 27.94 5.96 9.44 2.6 43.5 73.5 12.3 20.8 01/09/02 60 90 13 r s 29.44 27.83 5.47 8.62 0.6 10.4 27.3 2.7 7.1 01/09/02 0 15 3 r n 29.27 27.69 5.40 8.16 4.6 85.6 172.8 10.5 21.1 01/09/02 15 30 3 r n 29.37 27.86 5.14 8.08 3.8 73.3 45.1 8.9 5.5 01/09/02 30 60 3 r n 29.34 27.6 5.93 9.39 2.7 45.5 67.9 12.8 19.1 01/09/02 60 90 3 r n 29.84 28.32 5.09 8.00 0.9 18.5 37.4 4.4 9.0 01/09/02 0 15 4 r s 29.35 27.86 5.08 7.65 4.6 91.0 37.6 10.4 4.3 01/09/02 15 30 4 r s 29.54 27.89 5.59 8.81 7.5 134.2 59.4 17.7 7.9 01/09/02 30 60 4 r s 29.99 28.31 5.60 8.84 2.3 40.6 61.4 10.8 16.3 01/09/02 60 90 4 r s 29.27 27.79 5.06 7.94 0.9 18.6 105.3 4.4 25.1 01/09/02 0 15 6 r s 29.51 27.93 5.35 8.09 3.4 64.4 52.1 7.8 6.3 01/09/02 15 30 6 r s 29.18 27.48 5.83 9.22 1.8 31.7 50.9 4.4 7.0 01/09/02 30 60 6 r s 29.65 27.91 5.87 9.29 6.2 106.0 80.7 29.5 22.5 01/09/02 60 90 6 r s 30.61 29.12 4.87 7.62 7.1 145.3 57.3 33.2 13.1 01/09/02 0 15 7 r s 29.9 28.63 4.25 6.34 2.9 68.6 53.2 6.5 5.1 01/09/02 15 30 7 r s 32.23 30.48 5.43 8.55 1.1 20.3 72.0 2.6 9.2 01/09/02 30 60 7 r s 30.78 28.99 5.82 9.20 2.0 33.6 63.2 9.3 17.4 01/09/02 60 90 7 r s 33.07 31.17 5.75 9.08 2.7 47.0 37.3 12.8 10.2 01/23/02 0 15 8 r n 29.6 27.92 5.68 8.60 13.2 231.8 624.5 29.9 80.6 01/23/02 15 30 8 r n 29.37 27.43 6.61 10.54 87.8 1328.6 736.3 210.0 116.4 01/23/02 30 60 8 r n 29.85 27.94 6.40 10.19 5.4 83.9 50.0 25.6 15.3 01/23/02 60 90 8 r n 29.44 27.72 5.84 9.25 3.8 64.5 27.3 17.9 7.6 01/23/02 0 15 9 r n 29.48 27.72 5.97 9.08 1.4 23.8 161.2 3.2 22.0 01/23/02 15 30 9 r n 29.63 27.52 7.12 11.42 9.8 138.2 248.0 23.7 42.5 01/23/02 30 60 9 r n 29.72 27.47 7.57 12.20 4.9 65.2 91.5 23.9 33.5 01/23/02 60 90 9 r n 29.61 27.8 6.11 9.70 2.3 37.2 49.5 10.8 14.4 01/23/02 0 15 10 r n 29.45 27.72 5.87 8.92 0.5 7.9 114.0 1.1 15.3 01/23/02 15 30 10 r n 29.03 27.15 6.48 10.32 51.5 795.6 582.7 123.1 90.2 01/23/02 30 60 10 r n 29.52 27.39 7.22 11.59 2.2 30.8 34.8 10.7 12.1 01/23/02 60 90 10 r n 29.49 27.78 5.80 9.17 1.0 17.2 25.5 4.7 7.0 01/23/02 0 15 11 r n 29.64 27.88 5.94 9.03 9.4 157.7 365.1 21.3 49.4 01/23/02 15 30 11 r n 29.46 27.72 5.91 9.35 55.8 944.5 425.3 132.5 59.7 01/23/02 30 60 11 r n 29.97 28.36 5.37 8.46 4.3 80.0 70.2 20.3 17.8 01/23/02 60 90 11 r n 29.05 27.48 5.40 8.51 2.6 48.0 56.0 12.3 14.3 01/23/02 0 15 12 r s 29.56 28.19 4.63 6.95 126.2 2723.4 1829.1 283.9 190.7 01/23/02 15 30 12 r s 29.67 28.17 5.06 7.93 71.8 1419.7 701.1 169.0 83.4 01/23/02 30 60 12 r s 29.3 27.49 6.18 9.81 4.8 78.2 63.9 23.0 18.8 01/23/02 60 90 12 r s 30 28.33 5.57 8.78 2.3 40.9 41.0 10.8 10.8 01/23/02 0 15 13 r s 29.98 28.24 5.80 8.81 142.2 2450.2 1717.6 323.8 227.0 01/23/02 15 30 13 r s 29.38 27.53 6.30 10.01 41.4 657.4 271.4 98.7 40.8 01/23/02 30 60 13 r s 29.01 27.17 6.34 10.09 3.0 47.6 34.2 14.4 10.3 01/23/02 60 90 13 r s 29.79 28.04 5.87 9.30 2.6 44.2 20.3 12.3 5.7 01/23/02 0 15 3 r n 29.27 27.66 5.50 8.32 19.5 355.4 63.4 44.4 7.9 01/23/02 15 30 3 r n 29.24 27.57 5.71 9.03 54.7 958.1 379.5 129.7 51.4 01/23/02 30 60 3 r n 29.82 28.13 5.67 8.95 18.5 326.1 56.5 87.6 15.2 01/23/02 60 90 3 r n 29.47 27.69 6.04 9.58 2.8 46.5 34.0 13.4 9.8 01/23/02 0 15 4 r s 29.26 27.04 7.59 11.74 1.5 19.4 116.3 3.4 20.5 01/23/02 15 30 4 r s 29.62 27.8 6.14 9.75 59.0 959.9 464.8 140.5 68.0 01/23/02 30 60 4 r s 29.5 27.83 5.66 8.94 8.2 144.7 112.3 38.8 30.1 01/23/02 60 90 4 r s 29.46 27.64 6.18 9.81 1.4 23.0 23.9 6.8 7.0 01/23/02 0 15 6 r s 29.92 28.03 6.32 9.64 16.4 258.9 216.0 37.4 31.2 01/23/02 15 30 6 r s 29.16 27.43 5.93 9.40 5.0 85.0 110.0 12.0 15.5 01/23/02 30 60 6 r s 29.91 27.9 6.72 10.73 0.8 11.6 22.0 3.8 7.1

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123 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 01/23/02 60 90 6 r s 29.02 27.07 6.72 10.73 0.4 5.3 20.3 1.7 6.5 01/23/02 0 15 7 r s 29.4 27.67 5.88 8.94 4.3 73.1 128.5 9.8 17.2 01/23/02 15 30 7 r s 29.72 28.03 5.69 8.98 8.8 154.3 98.6 20.8 13.3 01/23/02 30 60 7 r s 29.85 28.08 5.93 9.39 0.9 15.9 36.6 4.5 10.3 01/23/02 60 90 7 r s 29.05 27.18 6.44 10.25 1.1 17.1 31.0 5.3 9.5 01/30/02 0 15 8 f n 29.79 28.17 5.44 8.22 1.3 23.5 48.2 2.9 5.9 01/30/02 15 30 8 f n 29.41 27.56 6.29 10.00 1.2 19.4 65.1 2.9 9.8 01/30/02 30 60 8 f n 29.38 27.83 5.28 8.30 1.2 23.2 35.1 5.8 8.7 01/30/02 60 90 8 f n 29.14 27.57 5.39 8.48 1.0 18.6 39.9 4.7 10.2 01/30/02 0 15 8 r n 29.94 28.26 5.61 8.50 2.8 49.5 792.6 6.3 101.1 01/30/02 15 30 8 r n 29.94 28.35 5.31 8.36 28.3 533.5 282.5 66.9 35.4 01/30/02 30 60 8 r n 29.38 27.62 5.99 9.49 21.4 357.0 108.7 101.7 31.0 01/30/02 60 90 8 r n 29.76 28.06 5.71 9.03 2.5 43.8 49.0 11.9 13.3 01/30/02 0 15 9 f n 29.02 27.32 5.86 8.90 0.8 13.3 66.9 1.8 8.9 01/30/02 15 30 9 f n 29.57 27.83 5.88 9.32 0.3 5.7 110.6 0.8 15.5 01/30/02 30 60 9 f n 29.4 27.72 5.71 9.03 0.3 5.8 59.3 1.6 16.1 01/30/02 60 90 9 f n 29.58 28.02 5.27 8.30 0.4 8.4 35.2 2.1 8.7 01/30/02 0 15 9 r n 29.36 27.54 6.20 9.45 8.1 130.8 365.6 18.5 51.8 01/30/02 15 30 9 r n 29.25 27.44 6.19 9.83 15.6 251.4 366.3 37.1 54.0 01/30/02 30 60 9 r n 29.25 27.67 5.40 8.51 2.4 45.3 35.4 11.6 9.0 01/30/02 60 90 9 r n 29.95 28.16 5.98 9.47 3.4 57.6 34.0 16.4 9.7 01/30/02 0 15 10 f n 29.51 27.76 5.93 9.01 0.7 11.2 67.0 1.5 9.1 01/30/02 15 30 10 f n 29.09 27.39 5.84 9.25 0.6 9.5 67.0 1.3 9.3 01/30/02 30 60 10 f n 29.21 27.62 5.44 8.58 0.4 8.2 74.1 2.1 19.1 01/30/02 60 90 10 f n 29.53 27.91 5.49 8.65 0.3 5.1 30.6 1.3 7.9 01/30/02 0 15 10 r n 29.14 27.39 6.01 9.14 0.7 11.1 153.6 1.5 21.0 01/30/02 15 30 10 r n 29.17 27.3 6.41 10.21 31.1 485.3 280.0 74.3 42.9 01/30/02 30 60 10 r n 29.07 27.21 6.40 10.19 10.1 158.0 81.5 48.3 24.9 01/30/02 60 90 10 r n 29.47 27.94 5.19 8.16 1.4 27.8 92.5 6.8 22.6 01/30/02 0 15 11 f n 29.88 28.21 5.59 8.47 1.2 21.9 19.5 2.8 2.5 01/30/02 15 30 11 f n 29.7 27.8 6.40 10.18 1.3 20.8 64.0 3.2 9.8 01/30/02 30 60 11 f n 29.77 27.96 6.08 9.65 1.2 20.1 43.1 5.8 12.5 01/30/02 60 90 11 f n 29.07 27.55 5.23 8.22 0.9 17.0 36.6 4.2 9.0 01/30/02 0 15 11 r n 29.07 27.48 5.47 8.27 3.7 67.0 72.7 8.3 9.0 01/30/02 15 30 11 r n 29.14 27.43 5.87 9.29 15.6 265.1 167.2 36.9 23.3 01/30/02 30 60 11 r n 29.15 27.38 6.07 9.63 4.2 69.5 34.4 20.1 9.9 01/30/02 60 90 11 r n 29.69 28.11 5.32 8.37 2.1 39.7 35.9 10.0 9.0 01/30/02 0 15 3 f n 29.25 27.27 6.77 10.38 0.7 9.8 26.5 1.5 4.1 01/30/02 15 30 3 f n 29.27 27.25 6.90 11.05 0.4 6.4 20.0 1.1 3.3 01/30/02 30 60 3 f n 29.54 27.73 6.13 9.73 0.5 8.2 38.0 2.4 11.1 01/30/02 60 90 3 f n 29.51 27.78 5.86 9.28 0.3 5.7 51.7 1.6 14.4 01/30/02 0 15 3 r n 29.37 27.52 6.30 9.61 2.3 36.2 247.5 5.2 35.7 01/30/02 15 30 3 r n 29.5 27.55 6.61 10.55 32.8 495.9 271.5 78.4 43.0 01/30/02 30 60 3 r n 29.45 27.43 6.86 10.97 6.4 93.1 53.7 30.7 17.7 01/30/02 60 90 3 r n 28.99 27.23 6.07 9.63 2.1 34.8 54.8 10.0 15.8 02/06/02 0 15 12 f s 29.2 28.08 3.84 5.70 0.4 11.5 24.4 1.0 2.1 02/06/02 15 30 12 f s 29.23 27.86 4.69 7.33 0.3 7.0 17.5 0.8 1.9 02/06/02 30 60 12 f s 29.35 27.99 4.63 7.24 0.3 7.1 27.5 1.5 6.0 02/06/02 60 90 12 f s 29.55 28.11 4.87 7.63 0.3 6.7 18.0 1.5 4.1 02/06/02 0 15 12 r s 29.27 28.13 3.89 5.80 38.8 996.3 1023.8 86.6 89.0 02/06/02 15 30 12 r s 29.8 28.53 4.26 6.63 31.9 749.1 577.4 74.5 57.4 02/06/02 30 60 12 r s 29.49 28.03 4.95 7.76 29.6 598.5 96.5 139.4 22.5 02/06/02 60 90 12 r s 29.64 28.21 4.82 7.55 1.1 23.4 42.8 5.3 9.7 02/06/02 0 15 13 f s 29.2 27.82 4.73 7.09 0.8 17.8 29.3 1.9 3.1 02/06/02 15 30 13 f s 29.9 28.35 5.18 8.15 0.3 6.3 14.8 0.8 1.8 02/06/02 30 60 13 f s 29.48 28.04 4.88 7.65 0.3 5.5 9.9 1.3 2.3 02/06/02 60 90 13 f s 29.79 28.41 4.63 7.24 0.3 7.1 39.7 1.5 8.6 02/06/02 0 15 13 r s 29.84 28.53 4.39 6.57 65.2 1484.4 1500.7 146.2 147.8 02/06/02 15 30 13 r s 29.31 27.75 5.32 8.38 41.1 772.1 281.8 97.0 35.4

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124 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 02/06/02 30 60 13 r s 29.2 27.69 5.17 8.13 12.8 247.6 42.1 60.4 10.3 02/06/02 60 90 13 r s 29.51 28.18 4.51 7.03 1.0 22.5 22.0 4.7 4.6 02/06/02 0 15 6 f s 29.11 27.71 4.81 7.22 0.6 12.8 30.0 1.4 3.3 02/06/02 15 30 6 f s 29.1 27.72 4.74 7.42 0.3 6.9 16.1 0.8 1.8 02/06/02 30 60 6 f s 29.61 28.27 4.53 7.06 0.3 7.2 36.9 1.5 7.8 02/06/02 60 90 6 f s 29.57 28.36 4.09 6.36 0.3 8.0 39.4 1.5 7.5 02/06/02 0 15 6 r s 29.22 27.86 4.65 6.98 8.5 181.9 322.2 19.0 33.7 02/06/02 15 30 6 r s 29.18 27.62 5.35 8.42 9.4 175.2 87.3 22.1 11.0 02/06/02 30 60 6 r s 29.52 27.97 5.25 8.26 0.6 10.6 16.7 2.6 4.1 02/06/02 60 90 6 r s 29.12 27.77 4.64 7.24 0.6 12.0 39.7 2.6 8.6 02/06/02 0 15 7 f s 29.58 28.33 4.23 6.31 0.4 10.4 48.9 1.0 4.6 02/06/02 15 30 7 f s 29.59 28.13 4.93 7.73 0.3 6.6 45.3 0.8 5.3 02/06/02 30 60 7 f s 29.15 27.73 4.87 7.63 0.3 5.5 34.3 1.3 7.8 02/06/02 60 90 7 f s 29.05 27.9 3.96 6.14 0.4 11.1 55.0 2.1 10.1 02/06/02 0 15 7 r s 29.2 27.98 4.18 6.24 3.9 92.9 223.6 8.7 20.9 02/06/02 15 30 7 r s 29.42 27.75 5.68 8.97 41.1 724.0 533.1 97.4 71.7 02/06/02 30 60 7 r s 29.33 27.91 4.84 7.58 3.5 73.0 75.4 16.6 17.1 02/06/02 60 90 7 r s 29.52 28.2 4.47 6.97 0.9 20.1 46.2 4.2 9.7 02/06/02 0 15 4 f s 29.33 28.18 3.92 5.84 0.7 18.6 51.2 1.6 4.5 02/06/02 15 30 4 f s 29.83 28.54 4.32 6.73 0.3 7.6 29.5 0.8 3.0 02/06/02 30 60 4 f s 29.21 27.85 4.66 7.28 0.3 5.8 27.4 1.3 6.0 02/06/02 60 90 4 f s 29.15 27.8 4.63 7.24 0.3 5.8 47.0 1.3 10.2 02/06/02 0 15 4 r s 29.19 27.9 4.42 6.61 14.2 320.3 608.0 31.8 60.3 02/06/02 15 30 4 r s 29.32 27.96 4.64 7.25 62.9 1355.5 932.8 147.4 101.4 02/06/02 30 60 4 r s 29.2 27.85 4.62 7.22 9.1 196.5 71.6 42.6 15.5 02/06/02 60 90 4 r s 29.01 27.73 4.41 6.88 2.4 54.2 71.2 11.2 14.7 02/21/02 0 15 8 f n 29.28 27.74 5.26 7.94 1.6 30.2 146.1 3.6 17.4 02/21/02 15 30 8 f n 29.72 28.23 5.01 7.86 0.5 9.9 59.8 1.2 7.0 02/21/02 30 60 8 f n 29.02 27.7 4.55 7.10 0.4 9.7 46.8 2.1 10.0 02/21/02 60 90 8 f n 29.06 27.71 4.65 7.26 10.3 221.7 98.1 48.3 21.4 02/21/02 0 15 8 r n 29.07 27.26 6.23 9.49 4.8 77.0 56.5 11.0 8.0 02/21/02 15 30 8 r n 29.83 28.44 4.66 7.28 7.7 164.4 250.4 18.0 27.3 02/21/02 30 60 8 r n 29.94 28.42 5.08 7.97 3.2 62.9 121.7 15.0 29.1 02/21/02 60 90 8 r n 29.42 27.99 4.86 7.61 3.5 72.8 36.6 16.6 8.4 02/21/02 0 15 9 f n 29.91 28.4 5.05 7.60 5.4 106.4 121.3 12.1 13.8 02/21/02 15 30 9 f n 29.13 27.78 4.63 7.24 1.1 24.4 129.6 2.6 14.1 02/21/02 30 60 9 f n 29.55 28.19 4.60 7.19 0.3 7.1 50.0 1.5 10.8 02/21/02 60 90 9 f n 29.23 28.04 4.07 6.32 0.8 19.3 97.8 3.7 18.5 02/21/02 0 15 9 r n 29.47 28.16 4.45 6.65 5.6 126.0 351.0 12.6 35.0 02/21/02 15 30 9 r n 29.41 28.04 4.66 7.28 2.6 56.2 179.9 6.1 19.6 02/21/02 30 60 9 r n 29.78 28.47 4.40 6.86 1.2 28.3 148.4 5.8 30.5 02/21/02 60 90 9 r n 29.1 27.94 3.99 6.19 0.9 22.6 121.6 4.2 22.6 02/21/02 0 15 10 f n 29.01 27.7 4.52 6.76 2.6 58.0 75.3 5.9 7.6 02/21/02 15 30 10 f n 29.66 28.3 4.59 7.16 0.8 17.1 81.7 1.8 8.8 02/21/02 30 60 10 f n 29.81 28.51 4.36 6.79 0.4 10.1 84.6 2.1 17.2 02/21/02 60 90 10 f n 29.42 28.19 4.18 6.50 0.3 7.8 64.7 1.5 12.6 02/21/02 0 15 10 r n 29.16 27.89 4.36 6.51 9.2 210.2 273.2 20.5 26.7 02/21/02 15 30 10 r n 29.95 28.57 4.61 7.20 8.9 192.4 197.0 20.8 21.3 02/21/02 30 60 10 r n 29.91 28.65 4.21 6.55 4.9 116.6 83.5 22.9 16.4 02/21/02 60 90 10 r n 29.58 28.42 3.92 6.08 2.3 59.5 66.1 10.9 12.1 02/21/02 0 15 11 f n 29.46 28.07 4.72 7.08 6.4 135.7 89.3 14.4 9.5 02/21/02 15 30 11 f n 29.05 27.57 5.09 8.00 1.8 35.7 87.2 4.3 10.5 02/21/02 30 60 11 f n 29.3 27.93 4.68 7.31 0.8 16.8 100.0 3.7 21.9 02/21/02 60 90 11 f n 29.47 28.25 4.14 6.43 0.4 10.7 51.4 2.1 9.9 02/21/02 0 15 11 r n 29.28 28 4.37 6.54 6.7 154.3 1307.8 15.1 128.2 02/21/02 15 30 11 r n 29.01 27.58 4.93 7.73 8.4 169.4 232.0 19.6 26.9 02/21/02 30 60 11 r n 29.4 28.1 4.42 6.89 8.6 194.0 86.1 40.1 17.8 02/21/02 60 90 11 r n 29.54 28.25 4.37 6.80 8.1 186.0 91.1 38.0 18.6 02/21/02 0 15 3 f n 29.44 27.98 4.96 7.46 4.7 94.4 184.2 10.6 20.6

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125 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 02/21/02 15 30 3 f n 29.71 28.01 5.72 9.04 2.3 39.8 45.3 5.4 6.1 02/21/02 30 60 3 f n 29.06 27.62 4.96 7.77 0.7 13.5 38.3 3.2 8.9 02/21/02 60 90 3 f n 29.38 28.13 4.25 6.62 0.7 15.8 73.1 3.1 14.5 02/21/02 0 15 3 r n 29.17 27.7 5.04 7.59 16.0 316.7 571.5 36.1 65.1 02/21/02 15 30 3 r n 29.08 27.58 5.16 8.10 7.5 146.3 288.9 17.8 35.1 02/21/02 30 60 3 r n 29.2 27.97 4.21 6.55 1.1 26.8 116.5 5.3 22.9 02/21/02 60 90 3 r n 29.25 27.84 4.82 7.55 1.6 32.9 118.6 7.5 26.8 02/27/02 0 15 12 f s 29.44 27.42 6.86 10.53 4.5 66.2 51.5 10.5 8.1 02/27/02 15 30 12 f s 29.11 27.35 6.05 9.59 3.8 63.3 38.2 9.1 5.5 02/27/02 30 60 12 f s 29.23 27.87 4.65 7.27 0.7 14.9 53.4 3.2 11.6 02/27/02 60 90 12 f s 29.73 28.32 4.74 7.42 0.4 7.7 64.6 1.7 14.4 02/27/02 0 15 12 r s 29.44 28.04 4.76 7.14 12.6 265.1 877.6 28.4 94.0 02/27/02 15 30 12 r s 29.39 27.92 5.00 7.84 34.3 685.0 519.8 80.6 61.2 02/27/02 30 60 12 r s 29.64 28.25 4.69 7.33 12.9 275.8 77.8 60.7 17.1 02/27/02 60 90 12 r s 29.86 28.67 3.99 6.18 3.5 87.8 55.0 16.3 10.2 02/27/02 0 15 13 f s 29.64 27.54 7.09 10.90 10.8 153.1 60.5 25.0 9.9 02/27/02 15 30 13 f s 29.8 27.95 6.21 9.86 2.8 45.7 30.6 6.8 4.5 02/27/02 30 60 13 f s 29.25 27.77 5.06 7.94 0.7 13.7 21.4 3.3 5.1 02/27/02 60 90 13 f s 29.64 28.07 5.30 8.33 0.3 5.8 38.1 1.5 9.5 02/27/02 0 15 13 r s 29.45 27.8 5.60 8.49 58.1 1036.5 3288.1 132.0 418.6 02/27/02 15 30 13 r s 29.08 27.44 5.64 8.91 44.2 783.0 440.3 104.6 58.8 02/27/02 30 60 13 r s 29.52 28.05 4.98 7.81 12.7 255.3 113.1 59.8 26.5 02/27/02 60 90 13 r s 29.29 27.78 5.16 8.10 2.5 48.6 88.9 11.8 21.6 02/27/02 0 15 6 f s 29.5 26.99 8.51 13.30 2.7 31.4 37.4 6.3 7.5 02/27/02 15 30 6 f s 29.69 28 5.69 8.99 2.0 34.4 47.7 4.6 6.4 02/27/02 30 60 6 f s 29.85 28.4 4.86 7.61 0.6 12.0 37.9 2.7 8.7 02/27/02 60 90 6 f s 29.27 28.24 3.52 5.43 0.2 5.6 52.4 0.9 8.5 02/27/02 0 15 6 r s 29.47 27.99 5.02 7.56 28.2 561.8 1329.9 63.7 150.8 02/27/02 15 30 6 r s 29.73 28.16 5.28 8.31 36.1 683.1 348.9 85.1 43.5 02/27/02 30 60 6 r s 29.23 27.77 4.99 7.83 9.0 180.1 94.0 42.3 22.1 02/27/02 60 90 6 r s 29.15 27.93 4.19 6.51 1.7 40.2 84.4 7.9 16.5 02/27/02 0 15 7 f s 29.2 27.33 6.40 9.78 2.9 46.0 73.4 6.8 10.8 02/27/02 15 30 7 f s 29.77 27.53 7.52 12.12 2.6 34.8 29.1 6.3 5.3 02/27/02 30 60 7 f s 29.26 27.31 6.66 10.64 0.8 12.0 39.9 3.8 12.7 02/27/02 60 90 7 f s 29.67 27.92 5.90 9.34 0.4 7.1 35.2 2.0 9.9 02/27/02 0 15 7 r s 29.47 27.8 5.67 8.59 35.6 628.9 1374.0 81.0 177.0 02/27/02 15 30 7 r s 29.37 27.52 6.30 10.02 92.2 1463.3 579.3 219.8 87.0 02/27/02 30 60 7 r s 29.35 27.22 7.26 11.66 12.8 176.7 65.5 61.8 22.9 02/27/02 60 90 7 r s 29.67 27.94 5.83 9.23 3.4 59.0 74.6 16.3 20.6 02/27/02 0 15 4 f s 29.82 27.94 6.30 9.62 2.2 34.5 45.9 5.0 6.6 02/27/02 15 30 4 f s 29.58 27.87 5.78 9.14 1.6 28.2 34.9 3.9 4.8 02/27/02 30 60 4 f s 29.49 27.95 5.22 8.21 0.6 11.2 42.0 2.7 10.3 02/27/02 60 90 4 f s 29.48 27.93 5.26 8.27 0.5 10.0 67.2 2.5 16.7 02/27/02 0 15 4 r s 29.51 27.76 5.93 9.01 29.0 489.6 713.5 66.2 96.5 02/27/02 15 30 4 r s 29.39 27.98 4.80 7.51 19.7 410.4 56.6 46.2 6.4 02/27/02 30 60 4 r s 29.75 27.96 6.02 9.54 5.5 91.0 51.9 26.1 14.9 02/27/02 60 90 4 r s 29.73 28.13 5.38 8.47 2.2 40.5 54.8 10.3 13.9 03/07/02 0 15 8 f n 29.4 27.72 5.71 8.67 0.8 14.5 86.3 1.9 11.2 03/07/02 15 30 8 f n 29.53 27.78 5.93 9.39 0.3 4.6 97.0 0.6 13.7 03/07/02 30 60 8 f n 29.31 27.67 5.60 8.83 0.3 4.9 106.9 1.3 28.3 03/07/02 60 90 8 f n 29.82 28.35 4.93 7.73 0.3 5.5 154.4 1.3 35.8 03/07/02 0 15 8 r n 29.71 28.1 5.42 8.19 3.8 70.7 393.7 8.7 48.4 03/07/02 15 30 8 r n 29.59 27.74 6.25 9.94 1.1 16.8 210.8 2.5 31.4 03/07/02 30 60 8 r n 29.11 27.53 5.43 8.55 1.4 25.5 105.9 6.5 27.2 03/07/02 60 90 8 r n 29.22 27.75 5.03 7.89 3.0 59.6 121.2 14.1 28.7 03/07/02 0 15 9 f n 29.63 28.02 5.43 8.22 0.9 17.3 69.3 2.1 8.5 03/07/02 15 30 9 f n 29.3 27.56 5.94 9.41 0.3 4.6 65.4 0.6 9.2 03/07/02 30 60 9 f n 29.73 28.2 5.15 8.08 0.3 5.3 93.5 1.3 22.7 03/07/02 60 90 9 f n 29.7 28.15 5.22 8.20 0.3 5.2 83.3 1.3 20.5

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126 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/07/02 0 15 10 r n 29.06 27.54 5.23 7.89 0.8 15.8 54.2 1.9 6.4 03/07/02 15 30 10 r n 29.61 27.86 5.91 9.36 0.4 6.5 38.1 0.9 5.3 03/07/02 30 60 10 r n 29.24 27.69 5.30 8.34 0.3 5.1 71.0 1.3 17.8 03/07/02 60 90 10 r n 29.93 28.39 5.15 8.08 0.3 5.3 34.7 1.3 8.4 03/07/02 0 15 11 f n 29.03 27.39 5.65 8.56 1.2 20.6 40.9 2.6 5.2 03/07/02 15 30 11 f n 29.5 27.56 6.58 10.49 0.4 5.8 20.9 0.9 3.3 03/07/02 30 60 11 f n 29.41 27.82 5.41 8.52 0.3 5.0 45.9 1.3 11.7 03/07/02 60 90 11 f n 29.01 27.52 5.14 8.07 0.3 5.3 37.0 1.3 9.0 03/07/02 0 15 11 r n 29.88 28.13 5.86 8.90 3.7 63.5 881.7 8.5 117.7 03/07/02 15 30 11 r n 29.68 27.87 6.10 9.68 1.9 31.8 184.6 4.6 26.8 03/07/02 30 60 11 r n 29.79 27.98 6.08 9.64 0.7 10.9 85.9 3.1 24.9 03/07/02 60 90 11 r n 29.38 27.81 5.34 8.41 3.6 66.5 53.0 16.8 13.4 03/07/02 0 15 3 f n 29.17 27.75 4.87 7.32 1.1 21.6 27.1 2.4 3.0 03/07/02 15 30 3 f n 29.35 27.43 6.54 10.43 0.6 9.3 25.5 1.4 4.0 03/07/02 30 60 3 f n 29.3 27.46 6.28 9.98 0.3 4.3 32.1 1.3 9.6 03/07/02 60 90 3 f n 29.68 28.05 5.49 8.66 0.3 4.9 34.6 1.3 9.0 03/07/02 0 15 3 r n 29.5 28.05 4.92 7.39 4.3 87.0 255.2 9.6 28.3 03/07/02 15 30 3 r n 29.31 27.39 6.55 10.44 1.2 17.7 459.1 2.8 71.9 03/07/02 30 60 3 r n 29.25 27.37 6.43 10.23 5.6 87.3 70.4 26.8 21.6 03/07/02 60 90 3 r n 29.69 28.15 5.19 8.15 13.8 266.9 31.0 65.3 7.6 03/15/02 0 15 12 f s 29.67 28.03 5.53 8.37 1.4 25.5 36.4 3.2 4.6 03/15/02 15 30 12 f s 29.57 27.78 6.05 9.60 0.9 14.2 38.6 2.0 5.6 03/15/02 30 60 12 f s 29.18 27.69 5.11 8.02 0.4 8.2 39.4 2.0 9.5 03/15/02 60 90 12 f s 29.21 28 4.14 6.44 0.5 11.4 30.2 2.2 5.8 03/15/02 0 15 12 r s 29.21 27.97 4.25 6.34 7.9 185.5 1217.8 17.6 115.8 03/15/02 15 30 12 r s 29.33 28.11 4.16 6.47 8.0 192.0 1426.0 18.6 138.3 03/15/02 30 60 12 r s 29.55 28.17 4.67 7.30 5.3 114.5 803.9 25.1 176.0 03/15/02 60 90 12 r s 29.42 28.12 4.42 6.89 3.2 71.7 283.0 14.8 58.5 03/15/02 0 15 13 f s 29.14 28.13 3.47 5.13 1.7 48.5 83.2 3.7 6.4 03/15/02 15 30 13 f s 29.87 27.55 7.77 12.55 0.6 8.2 46.9 1.5 8.8 03/15/02 30 60 13 f s 29.68 28.42 4.25 6.61 0.5 11.1 73.0 2.2 14.5 03/15/02 60 90 13 f s 29.63 28.35 4.32 6.73 0.4 9.7 74.3 2.0 15.0 03/15/02 0 15 13 r s 29.74 28.39 4.54 6.80 75.7 1667.0 1498.6 170.0 152.9 03/15/02 15 30 13 r s 29.12 27.64 5.08 7.98 10.3 202.6 331.7 24.2 39.7 03/15/02 30 60 13 r s 29.18 27.69 5.11 8.02 2.1 41.6 165.2 10.0 39.7 03/15/02 60 90 13 r s 29.37 27.95 4.83 7.57 3.7 76.9 120.4 17.5 27.4 03/15/02 0 15 6 f s 29.25 27.8 4.96 7.46 4.8 97.2 38.4 10.9 4.3 03/15/02 15 30 6 f s 29.69 27.99 5.73 9.05 4.2 72.6 61.8 9.9 8.4 03/15/02 30 60 6 f s 29.64 28.11 5.16 8.11 0.6 12.4 36.9 3.0 9.0 03/15/02 60 90 6 f s 29.62 28.24 4.66 7.28 0.8 17.2 57.2 3.8 12.5 03/15/02 0 15 6 r s 29.63 28.2 4.83 7.25 7.1 146.5 131.9 15.9 14.4 03/15/02 15 30 6 r s 29.6 28.09 5.10 8.01 3.3 65.3 60.8 7.8 7.3 03/15/02 30 60 6 r s 29.86 28.31 5.19 8.16 0.9 16.5 47.2 4.0 11.5 03/15/02 60 90 6 r s 29.19 27.92 4.35 6.78 0.7 15.9 48.8 3.2 9.9 03/15/02 0 15 7 f s 29.25 27.74 5.16 7.78 3.7 70.9 30.5 8.3 3.6 03/15/02 15 30 7 f s 29.44 27.95 5.06 7.94 1.7 34.3 37.6 4.1 4.5 03/15/02 30 60 7 f s 29.71 28.4 4.41 6.87 0.5 12.0 40.7 2.5 8.4 03/15/02 60 90 7 f s 29.77 28.55 4.10 6.37 0.5 11.5 70.4 2.2 13.4 03/15/02 0 15 7 r s 29.81 28.59 4.09 6.10 10.1 246.2 1130.2 22.5 103.4 03/15/02 15 30 7 r s 29.37 27.81 5.31 8.36 2.9 54.5 665.8 6.8 83.5 03/15/02 30 60 7 r s 29.71 28.42 4.34 6.76 4.1 94.5 262.9 19.2 53.3 03/15/02 60 90 7 r s 29.38 28.19 4.05 6.29 2.2 53.8 162.6 10.1 30.7 03/15/02 0 15 4 f s 29.74 28.26 4.98 7.49 1.1 21.7 62.3 2.4 7.0 03/15/02 15 30 4 f s 29.71 28.3 4.75 7.42 0.5 11.1 44.7 1.2 5.0 03/15/02 30 60 4 f s 29.36 28.12 4.22 6.57 0.3 6.0 52.8 1.2 10.4 03/15/02 60 90 4 f s 29.49 28.21 4.34 6.76 0.7 17.2 36.3 3.5 7.4 03/15/02 0 15 4 r s 29.52 28.27 4.23 6.32 26.0 614.3 1478.0 58.3 140.2 03/15/02 15 30 4 r s 29.31 27.79 5.19 8.15 16.9 326.6 703.0 39.9 85.9 03/15/02 30 60 4 r s 29.24 27.79 4.96 7.77 3.4 69.4 1854.8 16.2 432.6

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127 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/15/02 60 90 4 f s 29.49 28.21 4.34 6.76 0.7 17.2 36.3 3.5 7.4 03/15/02 0 15 4 r s 29.52 28.27 4.23 6.32 26.0 614.3 1478.0 58.3 140.2 03/15/02 15 30 4 r s 29.31 27.79 5.19 8.15 16.9 326.6 703.0 39.9 85.9 03/15/02 30 60 4 r s 29.24 27.79 4.96 7.77 3.4 69.4 1854.8 16.2 432.6 03/15/02 60 90 4 r s 29.87 28.6 4.25 6.62 3.1 71.9 160.0 14.3 31.8 03/20/02 0 15 8 f n 29.62 27.64 6.68 10.24 2.2 32.7 48.2 5.0 7.4 03/20/02 15 30 8 f n 29.72 27.7 6.80 10.87 1.1 16.5 28.9 2.7 4.7 03/20/02 30 60 8 f n 29.74 28.1 5.51 8.70 0.6 11.7 45.0 3.1 11.7 03/20/02 60 90 8 f n 29.53 28.13 4.74 7.42 0.3 5.8 51.1 1.3 11.4 03/20/02 0 15 8 r n 29.54 28 5.21 7.87 60.2 1154.5 640.0 136.2 75.5 03/20/02 15 30 8 r n 29.32 27.87 4.95 7.75 18.4 371.9 444.0 43.2 51.6 03/20/02 30 60 8 r n 29.89 28.21 5.62 8.87 3.4 59.8 390.7 15.9 104.0 03/20/02 60 90 8 r n 29.86 28.29 5.26 8.27 3.6 67.9 150.3 16.9 37.3 03/20/02 0 15 9 f n 29.74 27.86 6.32 9.65 1.9 29.6 47.4 4.3 6.9 03/20/02 15 30 9 f n 29.76 27.82 6.52 10.39 1.4 22.1 37.2 3.5 5.8 03/20/02 30 60 9 f n 29.62 28.01 5.44 8.56 0.7 12.9 128.6 3.3 33.0 03/20/02 60 90 9 f n 29.18 27.87 4.49 7.00 0.4 8.5 43.8 1.8 9.2 03/20/02 0 15 9 r n 29.46 27.85 5.47 8.27 38.6 706.4 777.6 87.6 96.4 03/20/02 15 30 9 r n 29.78 28.09 5.67 8.96 9.6 169.8 127.1 22.8 17.1 03/20/02 30 60 9 r n 29.64 27.92 5.80 9.18 3.7 63.4 122.4 17.5 33.7 03/20/02 60 90 9 r n 29.53 28.03 5.08 7.97 12.7 249.5 130.8 59.7 31.3 03/20/02 0 15 10 f n 29.43 27.5 6.56 10.04 2.9 44.7 43.1 6.7 6.5 03/20/02 15 30 10 f n 29.56 27.71 6.26 9.95 1.2 19.7 26.9 2.9 4.0 03/20/02 30 60 10 f n 29.63 28.03 5.40 8.51 0.8 14.9 39.6 3.8 10.1 03/20/02 60 90 10 f n 29.45 28.08 4.65 7.27 1.2 26.5 75.4 5.8 16.4 03/20/02 0 15 10 r n 29.91 28.34 5.25 7.92 83.6 1592.6 1037.8 189.2 123.3 03/20/02 15 30 10 r n 29.58 28.14 4.87 7.62 8.9 182.6 79.1 20.9 9.0 03/20/02 30 60 10 r n 29.62 28.08 5.20 8.17 5.1 97.3 70.8 23.9 17.3 03/20/02 60 90 10 r n 29.4 28.05 4.59 7.17 2.5 54.6 85.1 11.7 18.3 03/20/02 0 15 11 f n 29.73 27.83 6.39 9.76 3.4 53.4 57.6 7.8 8.4 03/20/02 15 30 11 f n 29.63 27.81 6.14 9.75 1.7 27.0 46.0 3.9 6.7 03/20/02 30 60 11 f n 29.24 27.66 5.40 8.51 1.0 18.8 45.9 4.8 11.7 03/20/02 60 90 11 f n 29.56 28.19 4.63 7.24 0.4 9.3 31.4 2.0 6.8 03/20/02 0 15 11 r n 29.88 28.21 5.59 8.47 48.5 867.5 382.7 110.2 48.6 03/20/02 15 30 11 r n 29.36 27.99 4.67 7.29 16.8 359.9 59.3 39.4 6.5 03/20/02 30 60 11 r n 29.2 27.66 5.27 8.30 4.4 83.9 158.4 20.9 39.4 03/20/02 60 90 11 r n 29.09 27.65 4.95 7.76 1.7 33.5 98.5 7.8 22.9 03/20/02 0 15 3 f n 29.31 27.32 6.79 10.42 2.6 38.5 32.3 6.0 5.1 03/20/02 15 30 3 f n 29.16 27.36 6.17 9.80 1.7 27.7 22.6 4.1 3.3 03/20/02 30 60 3 f n 29.69 28.03 5.59 8.82 0.7 12.5 37.2 3.3 9.9 03/20/02 60 90 3 f n 29.73 28.32 4.74 7.42 0.4 8.0 34.3 1.8 7.6 03/20/02 0 15 3 r n 29.07 27.48 5.47 8.27 31.5 575.2 162.2 71.4 20.1 03/20/02 15 30 3 r n 29.33 27.84 5.08 7.97 5.3 103.8 192.6 12.4 23.0 03/20/02 30 60 3 r n 29.19 27.66 5.24 8.24 2.3 43.8 174.7 10.8 43.2 03/20/02 60 90 3 r n 29.05 27.72 4.58 7.15 1.9 40.8 145.1 8.8 31.1 03/27/02 0 15 12 f s 29.71 27.78 6.50 9.93 2.3 35.4 44.0 5.3 6.6 03/27/02 15 30 12 f s 29.31 27.29 6.89 11.03 1.2 18.1 19.7 3.0 3.3 03/27/02 30 60 12 f s 29.33 27.66 5.69 9.00 1.4 23.8 44.1 6.4 11.9 03/27/02 60 90 12 f s 29.13 27.6 5.25 8.26 0.3 5.8 21.5 1.4 5.3 03/27/02 0 15 12 r s 29.34 28.16 4.02 5.99 75.8 1885.8 1399.9 169.5 125.8 03/27/02 15 30 12 r s 29.07 27.87 4.13 6.42 7.9 191.1 112.6 18.4 10.8 03/27/02 30 60 12 r s 29.08 27.37 5.88 9.31 6.3 107.8 95.7 30.1 26.7 03/27/02 60 90 12 r s 29.4 27.84 5.31 8.35 1.7 31.8 34.3 8.0 8.6 03/27/02 0 15 13 f s 29.81 27.79 6.78 10.39 1.6 23.3 25.2 3.6 3.9 03/27/02 15 30 13 f s 29.2 27.4 6.16 9.79 1.4 22.0 23.9 3.2 3.5 03/27/02 30 60 13 f s 29.47 27.96 5.12 8.05 0.7 13.5 55.8 3.3 13.5 03/27/02 60 90 13 f s 29.44 28.13 4.45 6.94 0.4 8.1 56.5 1.7 11.8 03/27/02 0 15 13 r s 29.76 28.08 5.65 8.56 21.7 384.9 343.0 49.4 44.0 03/27/02 15 30 13 r s 29.55 28.2 4.57 7.13 11.2 245.4 524.9 26.3 56.2

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128 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 03/27/02 30 60 13 r s 29.5 28.07 4.85 7.59 3.2 66.8 206.6 15.2 47.1 03/27/02 60 90 13 r s 29.22 27.85 4.69 7.33 1.9 40.7 121.3 9.0 26.7 03/27/02 0 15 6 f s 29.45 27.37 7.06 10.87 4.6 64.7 36.4 10.5 5.9 03/27/02 15 30 6 f s 29.28 27.31 6.73 10.75 1.9 28.4 30.5 4.6 4.9 03/27/02 30 60 6 f s 29.59 27.93 5.61 8.86 1.6 28.1 27.3 7.5 7.3 03/27/02 60 90 6 f s 29.49 28.15 4.54 7.09 0.5 11.6 59.1 2.5 12.6 03/27/02 0 15 6 r s 29.74 28.32 4.77 7.17 78.9 1652.1 1420.9 177.7 152.8 03/27/02 15 30 6 r s 29.34 27.97 4.67 7.30 6.0 128.6 150.2 14.1 16.4 03/27/02 30 60 6 r s 29.36 27.78 5.38 8.47 1.7 31.4 100.3 8.0 25.5 03/27/02 60 90 6 r s 29.55 28.08 4.97 7.80 2.0 40.6 50.5 9.5 11.8 03/27/02 0 15 7 f s 29.22 27.21 6.88 10.56 1.6 22.9 16.4 3.6 2.6 03/27/02 15 30 7 f s 29.48 27.84 5.56 8.78 0.9 15.4 34.8 2.0 4.6 03/27/02 30 60 7 f s 29.24 27.93 4.48 6.99 0.9 20.4 31.6 4.3 6.6 03/27/02 60 90 7 f s 29.53 28.19 4.54 7.08 0.3 6.7 30.0 1.4 6.4 03/27/02 0 15 7 r s 29.32 28.04 4.37 6.53 31.3 716.5 311.4 70.2 30.5 03/27/02 15 30 7 r s 29.3 28.02 4.37 6.81 5.3 122.3 58.9 12.5 6.0 03/27/02 30 60 7 r s 29.45 28.13 4.48 6.99 3.0 67.3 74.1 14.1 15.5 03/27/02 60 90 7 r s 29.14 27.85 4.43 6.90 5.3 120.7 78.9 25.0 16.3 03/27/02 0 15 4 f s 29.38 27.71 5.68 8.62 1.0 18.0 44.2 2.3 5.7 03/27/02 15 30 4 f s 29.31 27.44 6.38 10.15 0.8 12.6 47.5 1.9 7.2 03/27/02 30 60 4 f s 29.09 27.42 5.74 9.07 0.6 10.1 29.7 2.8 8.1 03/27/02 60 90 4 f s 29.41 27.99 4.83 7.56 0.4 7.5 41.3 1.7 9.4 03/27/02 0 15 4 r s 29.14 27.55 5.46 8.25 51.2 938.5 158.2 116.2 19.6 03/27/02 15 30 4 r s 29.49 28.09 4.75 7.43 57.8 1218.5 31.1 135.7 3.5 03/27/02 30 60 4 r s 29.39 28.03 4.63 7.23 22.3 481.5 41.8 104.4 9.1 03/27/02 60 90 4 r s 29.15 27.81 4.60 7.18 8.4 183.6 54.7 39.6 11.8 04/03/02 0 15 8 f n 29.66 27.38 7.69 11.91 1.2 16.0 24.7 2.9 4.4 04/03/02 15 30 8 f n 29.06 26.97 7.19 11.55 0.2 3.5 10.0 0.6 1.7 04/03/02 30 60 8 f n 29.22 27.34 6.43 10.25 0.4 6.4 33.1 2.0 10.2 04/03/02 60 90 8 f n 29.13 27.26 6.42 10.22 0.5 7.3 25.0 2.2 7.7 04/03/02 0 15 8 r n 29.32 27.4 6.55 10.02 23.2 354.0 397.2 53.2 59.7 04/03/02 15 30 8 r n 29.84 27.93 6.40 10.19 60.2 940.6 287.0 143.8 43.9 04/03/02 30 60 8 r n 29 27.32 5.79 9.16 7.2 123.7 225.9 34.0 62.1 04/03/02 60 90 8 r n 29 27.31 5.83 9.22 1.6 26.7 74.9 7.4 20.7 04/03/02 0 15 9 f n 29.2 27.38 6.23 9.51 0.7 11.9 88.8 1.7 12.7 04/03/02 15 30 9 f n 29.33 27.5 6.24 9.92 0.6 10.1 44.5 1.5 6.6 04/03/02 30 60 9 f n 29.71 27.91 6.06 9.61 0.3 5.0 35.2 1.4 10.1 04/03/02 60 90 9 f n 29.13 27.2 6.63 10.57 0.6 8.7 23.3 2.8 7.4 04/03/02 0 15 9 r n 29.24 27.35 6.46 9.88 3.7 57.8 38.4 8.6 5.7 04/03/02 15 30 9 r n 29.92 28.24 5.61 8.86 21.0 374.1 52.6 49.7 7.0 04/03/02 30 60 9 r n 29.68 27.82 6.27 9.96 31.9 509.0 76.2 152.1 22.8 04/03/02 60 90 9 r n 29.58 27.92 5.61 8.86 13.9 248.2 56.8 66.0 15.1 04/03/02 0 15 10 f n 29.07 26.8 7.81 12.11 0.7 8.8 34.8 1.6 6.3 04/03/02 15 30 10 f n 29.14 27.02 7.28 11.69 0.5 7.2 27.7 1.3 4.9 04/03/02 30 60 10 f n 29.65 27.54 7.12 11.42 0.4 5.8 16.7 2.0 5.7 04/03/02 60 90 10 f n 29.53 27.59 6.57 10.48 0.3 4.6 14.6 1.5 4.6 04/03/02 0 15 10 r n 29.29 27.36 6.59 10.09 19.9 302.3 269.9 45.7 40.8 04/03/02 15 30 10 r n 29.55 27.71 6.23 9.89 38.4 617.2 200.7 91.6 29.8 04/03/02 30 60 10 r n 29.86 27.98 6.30 10.01 15.6 247.2 88.0 74.2 26.4 04/03/02 60 90 10 r n 29.04 27.32 5.92 9.38 4.5 75.9 26.1 21.4 7.3 04/03/02 0 15 11 f n 29.01 26.9 7.27 11.22 0.8 10.9 34.1 1.8 5.7 04/03/02 15 30 11 f n 29.52 27.37 7.28 11.70 0.5 6.4 8.3 1.1 1.5 04/03/02 30 60 11 f n 29.06 27.03 6.99 11.19 0.7 9.8 22.1 3.3 7.4 04/03/02 60 90 11 f n 29.25 27.39 6.36 10.12 0.8 13.3 13.2 4.0 4.0 04/03/02 0 15 11 r n 29.49 27.52 6.68 10.24 23.2 347.1 204.7 53.3 31.4 04/03/02 15 30 11 r n 29.02 27.43 5.48 8.64 25.4 462.9 51.8 60.0 6.7 04/03/02 30 60 11 r n 29.25 27.53 5.88 9.31 12.3 209.1 40.2 58.4 11.2 04/03/02 60 90 11 r n 29.61 27.86 5.91 9.36 3.2 54.0 53.9 15.2 15.1 04/03/02 0 15 3 f n 29.53 27.21 7.86 12.19 0.6 7.3 37.6 1.3 6.9

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129 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 04/03/02 15 30 3 f n 29.22 26.95 7.77 12.55 0.5 6.0 16.1 1.1 3.0 04/03/02 30 60 3 f n 29.22 27.26 6.71 10.71 0.3 4.5 16.0 1.5 5.1 04/03/02 60 90 3 f n 29.78 27.82 6.58 10.50 0.2 3.8 11.8 1.2 3.7 04/03/02 0 15 3 r n 29.12 27.06 7.07 10.89 3.1 43.5 53.4 7.1 8.7 04/03/02 15 30 3 r n 29.14 27.17 6.76 10.80 6.0 89.1 118.4 14.4 19.2 04/03/02 30 60 3 r n 29.98 27.81 7.24 11.63 23.2 320.3 118.7 111.7 41.4 04/03/02 60 90 3 r n 29.69 27.65 6.87 10.99 12.8 186.9 125.0 61.6 41.2 04/12/02 0 15 13 f s 28.98 26.39 8.94 14.03 0.7 7.7 27.1 1.6 5.7 04/12/02 15 30 13 f s 29.42 27.02 8.16 13.23 0.4 5.1 24.7 1.0 4.9 04/12/02 30 60 13 f s 29.23 27.23 6.84 10.94 0.4 5.2 19.1 1.7 6.3 04/12/02 60 90 13 f s 29.69 27.75 6.53 10.42 0.9 13.8 14.6 4.3 4.6 04/12/02 0 15 13 r s 29 26.82 7.52 11.62 12.3 163.6 172.3 28.5 30.0 04/12/02 15 30 13 r s 29.08 27.07 6.91 11.06 23.2 335.4 47.8 55.7 7.9 04/12/02 30 60 13 r s 29.21 27.14 7.09 11.36 3.0 41.9 19.3 14.3 6.6 04/12/02 60 90 13 r s 29.95 27.71 7.48 12.04 4.9 65.9 33.2 23.8 12.0 04/12/02 0 15 4 f s 29.46 26.85 8.86 13.90 0.8 9.6 24.1 2.0 5.0 04/12/02 15 30 4 f s 29.65 26.94 9.14 14.99 1.1 12.3 13.0 2.8 2.9 04/12/02 30 60 4 f s 29.77 26.92 9.57 15.77 0.5 4.9 18.0 2.3 8.5 04/12/02 60 90 4 f s 29.4 27.04 8.03 13.00 0.7 8.5 13.4 3.3 5.2 04/12/02 0 15 4 r s 29.36 27.12 7.63 11.81 10.2 133.2 31.0 23.6 5.5 04/12/02 15 30 4 r s 29.25 27.24 6.87 10.99 82.0 1193.1 202.2 196.8 33.3 04/12/02 30 60 4 r s 29.8 27.09 9.09 14.91 12.3 135.2 7.9 60.5 3.5 04/12/02 60 90 4 r s 29.63 27 8.88 14.51 3.2 35.9 14.7 15.6 6.4 04/17/02 0 15 8 f n 29.57 26.71 9.67 15.31 1.0 10.3 469.6 2.4 107.8 04/17/02 15 30 8 f n 29.01 26.55 8.48 13.81 0.4 4.2 25.1 0.9 5.2 04/17/02 30 60 8 f n 29.72 27.58 7.20 11.56 0.2 2.8 102.9 1.0 35.7 04/17/02 60 90 8 f n 29.39 27.42 6.70 10.70 0.3 4.6 139.7 1.5 44.9 04/17/02 0 15 8 r n 29.25 26.9 8.03 12.49 7.9 98.8 215.2 18.5 40.3 04/17/02 15 30 8 r n 29.29 27.3 6.79 10.86 31.9 469.1 63.5 76.4 10.3 04/17/02 30 60 8 r n 29.79 27.98 6.08 9.64 8.1 133.2 28.5 38.5 8.2 04/17/02 0 15 9 f n 29.26 26.8 8.41 13.13 0.7 8.7 39.0 1.7 7.7 04/17/02 15 30 9 f n 29.13 26.97 7.42 11.93 0.3 4.1 61.2 0.7 11.0 04/17/02 30 60 9 f n 29.33 27.39 6.61 10.55 0.4 6.2 90.4 2.0 28.6 04/17/02 60 90 9 f n 29.17 27.18 6.82 10.91 0.3 4.5 43.9 1.5 14.4 04/17/02 0 15 9 r n 29.27 26.75 8.61 13.47 3.0 34.5 26.1 7.0 5.3 04/17/02 15 30 9 r n 29.36 27.51 6.30 10.02 10.5 167.2 93.0 25.1 14.0 04/17/02 30 60 9 r n 29.11 27.19 6.60 10.52 9.5 143.8 34.1 45.4 10.7 04/17/02 60 90 9 r n 29.31 27.45 6.35 10.10 12.7 199.6 210.1 60.4 63.6 04/17/02 0 15 10 f n 28.94 26.28 9.19 14.47 1.2 12.6 250.6 2.7 54.4 04/17/02 15 30 10 f n 29.08 26.79 7.87 12.74 0.4 5.2 379.9 1.0 72.6 04/17/02 30 60 10 f n 29.42 27.57 6.29 10.00 2.8 43.9 50.3 13.2 15.1 04/17/02 60 90 10 f n 29.12 27.21 6.56 10.46 0.4 6.3 359.9 2.0 112.9 04/17/02 0 15 10 r n 29.21 26.84 8.11 12.63 34.5 425.7 206.1 80.6 39.0 04/17/02 15 30 10 r n 29.83 27.77 6.91 11.05 21.2 307.0 117.3 50.9 19.4 04/17/02 30 60 10 r n 29.66 27.93 5.83 9.23 10.5 180.5 103.4 50.0 28.6 04/17/02 60 90 10 r n 29.47 27.71 5.97 9.46 4.1 68.6 63.6 19.5 18.0 04/17/02 0 15 11 f n 29.21 26.54 9.14 14.39 1.1 12.1 55.3 2.6 11.9 04/17/02 15 30 11 f n 28.98 26.85 7.35 11.82 0.3 4.2 64.1 0.7 11.4 04/17/02 30 60 11 f n 29.14 27.13 6.90 11.04 0.5 7.5 73.3 2.5 24.3 04/17/02 60 90 11 f n 29.07 27.45 5.57 8.79 0.3 4.5 96.9 1.2 25.6 04/17/02 0 15 11 r n 29.95 27.21 9.15 14.40 4.1 45.3 49.0 9.8 10.6 04/17/02 15 30 11 r n 29.75 27.81 6.52 10.39 18.0 276.0 91.7 43.0 14.3 04/17/02 30 60 11 r n 29.19 27.2 6.82 10.90 26.5 389.2 78.4 127.3 25.6 04/17/02 60 90 11 r n 28.97 27.2 6.11 9.70 15.9 259.7 61.2 75.5 17.8 04/17/02 0 15 3 f n 29.64 26.94 9.11 14.33 3.5 37.9 58.0 8.2 12.5 04/17/02 15 30 3 f n 29.4 27 8.16 13.24 0.4 4.4 155.6 0.9 30.9 04/17/02 30 60 3 f n 29.21 26.92 7.84 12.67 0.8 10.0 27.2 3.8 10.3 04/17/02 60 90 3 f n 29.8 27.7 7.05 11.30 0.4 5.9 20.5 2.0 6.9 04/17/02 0 15 3 r n 29.59 27.28 7.81 12.11 1.0 12.8 214.2 2.3 38.9

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130 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 04/17/02 15 30 3 r n 29.16 27.14 6.93 11.09 10.4 150.5 50.6 25.0 8.4 04/17/02 30 60 3 r n 29.45 27.41 6.93 11.09 16.9 244.4 48.2 81.3 16.0 04/17/02 60 90 3 r n 29.54 27.42 7.18 11.52 28.7 399.5 53.7 138.1 18.6 04/24/02 0 15 12 f s 29.09 27.01 7.15 11.01 1.3 17.8 93.4 2.9 15.4 04/24/02 15 30 12 f s 29.05 27.05 6.88 11.02 0.3 4.4 41.9 0.7 6.9 04/24/02 30 60 12 f s 29.26 27.22 6.97 11.17 0.4 5.1 44.7 1.7 15.0 04/24/02 60 90 12 f s 29.49 27.83 5.63 8.89 0.4 6.3 52.3 1.7 13.9 04/24/02 0 15 12 r s 29.05 27.38 5.75 8.72 2.3 39.9 113.1 5.2 14.8 04/24/02 15 30 12 r s 29.18 27.77 4.83 7.57 7.5 155.3 84.6 17.6 9.6 04/24/02 30 60 12 r s 29.57 28.09 5.01 7.85 12.7 253.8 63.4 59.8 14.9 04/24/02 60 90 12 r s 29.52 27.94 5.35 8.43 10.6 197.1 47.4 49.8 12.0 04/24/02 0 15 13 f s 29.25 26.88 8.10 12.61 1.2 14.3 45.5 2.7 8.6 04/24/02 15 30 13 f s 29.51 27.44 7.01 11.24 0.6 8.9 39.5 1.5 6.7 04/24/02 30 60 13 f s 29.03 27.22 6.23 9.91 0.5 8.3 58.2 2.5 17.3 04/24/02 60 90 13 f s 29.08 27.31 6.09 9.66 0.5 8.5 38.9 2.5 11.3 04/24/02 0 15 13 r s 29.84 28.18 5.56 8.42 26.7 479.6 497.7 60.6 62.9 04/24/02 15 30 13 r s 29.02 27.77 4.31 6.71 40.7 943.9 261.9 95.0 26.4 04/24/02 30 60 13 r s 29.1 27.51 5.46 8.61 16.5 301.3 162.1 77.9 41.9 04/24/02 60 90 13 r s 29.06 27.41 5.68 8.97 9.5 166.9 99.4 44.9 26.7 04/24/02 0 15 6 f s 29.33 26.87 8.39 13.09 2.5 29.2 74.1 5.7 14.6 04/24/02 15 30 6 f s 29.54 27.45 7.08 11.34 0.6 8.8 277.7 1.5 47.3 04/24/02 30 60 6 f s 29.15 27.32 6.28 9.98 0.6 9.1 157.6 2.7 47.2 04/24/02 60 90 6 f s 29.8 28.11 5.67 8.96 0.3 5.3 49.8 1.4 13.4 04/24/02 0 15 6 r s 29.23 27.51 5.88 8.94 21.3 362.0 314.3 48.6 42.2 04/24/02 15 30 6 r s 29.61 28.2 4.76 7.45 18.6 390.9 106.4 43.7 11.9 04/24/02 30 60 6 r s 29.66 27.92 5.87 9.29 11.6 198.2 62.9 55.2 17.5 04/24/02 60 90 6 r s 29.07 27.5 5.40 8.51 6.5 121.1 37.4 30.9 9.6 04/24/02 0 15 7 f s 29.44 27.22 7.54 11.66 1.1 14.7 52.7 2.6 9.2 04/24/02 15 30 7 f s 29.69 27.53 7.28 11.69 0.9 12.3 167.4 2.2 29.4 04/24/02 30 60 7 f s 29.56 27.67 6.39 10.18 0.3 4.7 77.5 1.4 23.6 04/24/02 60 90 7 f s 29.09 27.47 5.57 8.79 0.2 4.5 55.9 1.2 14.7 04/24/02 0 15 7 r s 29.12 27.58 5.29 7.98 2.3 44.3 89.3 5.3 10.7 04/24/02 15 30 7 r s 29.11 28.03 3.71 5.74 12.7 342.3 149.0 29.5 12.8 04/24/02 30 60 7 r s 29.37 27.86 5.14 8.08 5.0 97.9 69.5 23.7 16.8 04/24/02 60 90 7 r s 29.79 28.28 5.07 7.96 9.5 186.9 70.5 44.6 16.8 04/24/02 0 15 4 f s 29.35 27.24 7.19 11.08 0.9 13.2 47.3 2.2 7.9 04/24/02 15 30 4 f s 29.48 27.44 6.92 11.08 0.4 5.9 209.2 1.0 34.8 04/24/02 30 60 4 f s 29.32 27.45 6.38 10.15 0.4 5.6 30.8 1.7 9.4 04/24/02 60 90 4 f s 29.25 27.53 5.88 9.31 0.5 8.8 110.6 2.5 30.9 04/24/02 0 15 4 r s 29.63 27.56 6.99 10.74 3.5 49.7 59.4 8.0 9.6 04/24/02 15 30 4 r s 29.04 27.76 4.41 6.87 20.2 458.9 125.4 47.3 12.9 04/24/02 30 60 4 r s 29.19 27.56 5.58 8.81 33.7 602.9 78.4 159.4 20.7 04/24/02 60 90 4 r s 29.29 27.65 5.60 8.84 36.4 649.3 47.4 172.2 12.6 05/01/02 0 15 8 f n 29.11 26.74 4.67 12.67 1.5 31.8 113.4 6.0 21.6 05/01/02 15 30 8 f n 29.18 27.05 3.84 11.73 0.6 16.3 42.2 2.9 7.4 05/01/02 30 60 8 f n 29.44 27.53 3.02 10.34 0.6 18.9 38.4 5.9 11.9 05/01/02 60 90 8 f n 29.26 27.59 2.22 9.02 0.5 20.9 129.8 5.6 35.1 05/01/02 0 15 8 r n 29.27 26.99 4.34 12.08 2.1 47.9 37.3 8.7 6.8 05/01/02 15 30 8 r n 29.89 28.22 2.21 8.82 1.4 62.4 49.9 8.3 6.6 05/01/02 30 60 8 r n 29.8 28 2.65 9.58 0.9 35.7 28.6 10.3 8.2 05/01/02 60 90 8 r n 29.33 27.65 2.28 9.05 1.3 55.6 189.1 15.1 51.4 05/01/02 0 15 9 f n 29.79 27.79 3.29 10.29 3.6 110.5 51.0 17.1 7.9 05/01/02 15 30 9 f n 29.61 27.71 2.94 10.22 2.6 87.1 31.7 13.4 4.9 05/01/02 30 60 9 f n 29.86 28.12 2.38 9.22 1.9 78.3 44.0 21.7 12.2 05/01/02 60 90 9 f n 29.41 27.9 1.67 8.06 1.3 76.2 114.5 18.4 27.7 05/01/02 0 15 9 r n 29.06 27.06 3.37 10.57 9.1 270.4 102.6 42.9 16.3 05/01/02 15 30 9 r n 29.16 27.72 1.44 7.74 26.7 1852.3 104.5 215.1 12.1 05/01/02 30 60 9 r n 29.11 27.59 1.31 8.21 19.2 1467.2 106.5 361.3 26.2 05/01/02 60 90 9 r n 29.54 28.05 1.08 7.91 9.4 869.8 80.6 206.5 19.1

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131 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/01/02 0 15 10 f n 29.23 26.9 3.97 12.39 1.1 27.9 33.6 5.2 6.2 05/01/02 15 30 10 f n 29.12 26.95 3.43 12.00 0.7 21.3 23.8 3.8 4.3 05/01/02 30 60 10 f n 29.36 27.38 2.72 10.78 0.7 26.9 84.8 8.7 27.4 05/01/02 60 90 10 f n 29.09 27.46 1.58 8.84 0.8 49.7 22.5 13.2 6.0 05/01/02 0 15 10 r n 29.7 27.96 1.92 8.90 5.7 295.9 69.4 39.5 9.3 05/01/02 15 30 10 r n 29.58 28.05 1.22 8.13 45.0 3694.1 180.3 450.3 22.0 05/01/02 30 60 10 r n 29.41 27.5 2.48 10.35 3.6 146.5 51.4 45.5 16.0 05/01/02 60 90 10 r n 29.54 27.75 2.10 9.61 19.7 938.1 140.1 270.5 40.4 05/01/02 0 15 11 f n 29.14 26.81 4.26 12.43 1.6 37.4 48.9 7.0 9.1 05/01/02 15 30 11 f n 29.3 27.45 2.59 10.04 0.5 19.9 46.9 3.0 7.1 05/01/02 30 60 11 f n 29.52 27.73 2.37 9.62 0.5 21.8 141.0 6.3 40.7 05/01/02 60 90 11 f n 29.23 27.54 1.98 9.14 0.4 20.7 38.2 5.7 10.5 05/01/02 0 15 11 r n 29.09 27.07 3.13 10.67 2.1 66.4 44.4 10.6 7.1 05/01/02 15 30 11 r n 29 27.58 1.03 7.67 7.7 746.4 145.5 85.9 16.7 05/01/02 30 60 11 r n 28.96 27.3 1.93 9.06 4.9 254.7 71.9 69.2 19.5 05/01/02 60 90 11 r n 29.49 27.72 2.17 9.51 3.5 160.1 40.2 45.7 11.5 05/01/02 0 15 3 f n 28.92 26.97 2.90 10.34 2.1 73.3 43.9 11.4 6.8 05/01/02 15 30 3 f n 29.1 27.06 3.16 11.23 1.8 57.2 38.5 9.6 6.5 05/01/02 30 60 3 f n 29.01 27.24 2.24 9.68 1.1 47.1 59.5 13.7 17.3 05/01/02 60 90 3 f n 29.41 27.9 1.36 8.06 0.4 26.2 68.4 6.3 16.6 05/01/02 0 15 3 r n 29.53 27.31 4.10 11.62 1.3 31.0 22.7 5.4 4.0 05/01/02 15 30 3 r n 29.09 27.33 2.27 9.60 17.0 749.4 122.0 107.9 17.6 05/01/02 30 60 3 r n 29.55 27.89 2.23 8.87 3.9 172.4 118.8 45.9 31.6 05/01/02 60 90 3 r n 29.17 27.48 2.37 9.16 8.5 360.5 202.1 99.1 55.5 05/06/02 0 15 12 f s 29.62 28.40 4.12 6.14 1.1 27.6 118.5 2.5 10.9 05/06/02 15 30 12 f s 29.32 27.76 5.32 8.37 0.4 6.7 97.2 0.8 12.2 05/06/02 30 60 12 f s 29.28 27.82 4.99 7.82 0.4 7.2 102.6 1.7 24.1 05/06/02 60 90 12 f s 29.58 28.18 4.73 7.40 0.4 7.6 81.1 1.7 18.0 05/06/02 0 15 12 r s 29.43 28.54 3.02 4.46 2.4 78.0 165.3 5.2 11.1 05/06/02 15 30 12 r s 29.51 28.79 2.44 3.73 5.7 233.5 228.6 13.0 12.8 05/06/02 30 60 12 r s 29.56 28.16 4.74 7.41 2.5 53.3 58.9 11.9 13.1 05/06/02 60 90 12 r s 29.19 27.85 4.59 7.17 1.1 24.8 68.4 5.3 14.7 05/06/02 0 15 13 f s 29.83 28.11 5.77 8.75 2.7 46.7 61.5 6.1 8.1 05/06/02 15 30 13 f s 29.40 27.37 6.90 11.05 1.5 21.3 51.4 3.5 8.5 05/06/02 30 60 13 f s 29.89 27.56 7.80 12.60 1.5 18.9 73.0 7.1 27.6 05/06/02 60 90 13 f s 29.15 27.19 6.72 10.74 1.7 26.0 42.4 8.4 13.7 05/06/02 0 15 13 r s 29.76 28.38 4.64 6.95 1.9 40.1 92.7 4.2 9.7 05/06/02 15 30 13 r s 29.18 27.86 4.52 7.06 6.0 133.3 154.1 14.1 16.3 05/06/02 30 60 13 r s 29.20 27.59 5.51 8.69 7.4 134.6 78.0 35.1 20.3 05/06/02 60 90 13 r s 29.64 28.00 5.53 8.73 4.9 88.9 113.4 23.3 29.7 05/06/02 0 15 6 f s 29.21 27.67 5.27 7.96 1.4 25.8 133.3 3.1 15.9 05/06/02 15 30 6 f s 28.96 27.42 5.32 8.37 0.7 14.1 74.3 1.8 9.3 05/06/02 30 60 6 f s 29.48 27.92 5.29 8.33 0.3 5.7 53.8 1.4 13.4 05/06/02 60 90 6 f s 29.45 27.81 5.57 8.79 0.3 5.4 46.0 1.4 12.1 05/06/02 0 15 6 r s 29.29 28.40 3.04 4.48 2.6 85.0 126.3 5.7 8.5 05/06/02 15 30 6 r s 28.96 27.98 3.38 5.22 19.9 586.9 188.9 45.9 14.8 05/06/02 30 60 6 r s 29.11 27.56 5.32 8.38 6.8 126.8 52.4 31.9 13.2 05/06/02 60 90 6 r s 29.68 28.14 5.19 8.15 3.5 66.9 67.2 16.4 16.4 05/06/02 0 15 7 f s 29.76 28.29 4.94 7.43 0.6 11.8 65.9 1.3 7.3 05/06/02 15 30 7 f s 29.24 27.74 5.13 8.06 0.4 7.0 62.3 0.8 7.5 05/06/02 30 60 7 f s 29.69 28.04 5.56 8.77 0.4 6.4 62.8 1.7 16.5 05/06/02 60 90 7 f s 28.94 27.46 5.11 8.03 0.4 7.0 87.5 1.7 21.1 05/06/02 0 15 7 r s 29.38 28.35 3.51 5.20 1.8 51.4 253.5 4.0 19.8 05/06/02 15 30 7 r s 29.78 28.94 2.82 4.32 5.3 186.2 197.8 12.1 12.8 05/06/02 30 60 7 r s 29.01 27.66 4.65 7.27 4.5 96.1 33.8 21.0 7.4 05/06/02 60 90 7 r s 29.41 27.99 4.83 7.56 1.3 27.0 24.1 6.1 5.5 05/06/02 0 15 4 f s 28.95 27.42 5.28 7.98 0.6 11.0 8.9 1.3 1.1 05/06/02 15 30 4 f s 29.49 27.77 5.83 9.23 0.4 7.1 10.0 1.0 1.4 05/06/02 30 60 4 f s 28.92 27.31 5.57 8.78 0.2 4.4 33.5 1.2 8.8

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132 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/06/02 60 90 4 f s 28.91 27.37 5.33 8.38 0.2 4.6 27.3 1.2 6.9 05/06/02 0 15 4 r s 29.28 27.95 4.54 6.80 1.0 22.6 89.6 2.3 9.1 05/06/02 15 30 4 r s 29.00 27.47 5.28 8.30 0.7 14.2 154.1 1.8 19.2 05/06/02 30 60 4 r s 29.57 27.90 5.65 8.92 0.9 16.2 55.6 4.3 14.9 05/06/02 60 90 4 r s 29.17 27.46 5.86 9.28 0.8 13.7 49.6 3.8 13.8 05/15/02 0 15 8 f n 29.36 27.78 5.38 8.13 2.0 37.8 37.8 4.6 4.6 05/15/02 15 30 8 f n 29.12 27.51 5.53 8.72 2.6 47.7 58.9 6.2 7.7 05/15/02 30 60 8 f n 29.18 27.73 4.97 7.79 0.5 10.3 32.8 2.4 7.7 05/15/02 60 90 8 f n 29.30 28.01 4.40 6.86 0.5 10.4 44.9 2.1 9.3 05/15/02 0 15 8 r n 29.18 27.88 4.46 6.67 3.6 81.2 96.5 8.1 9.7 05/15/02 15 30 8 r n 29.70 28.80 3.03 4.66 2.0 65.4 118.9 4.6 8.3 05/15/02 30 60 8 r n 29.13 27.96 4.02 6.23 1.0 24.9 86.8 4.7 16.2 05/15/02 60 90 8 r n 29.81 28.55 4.23 6.58 1.5 36.6 61.9 7.2 12.2 05/15/02 0 15 9 f n 29.34 27.83 5.15 7.76 1.8 35.3 72.3 4.1 8.4 05/15/02 15 30 9 f n 29.06 27.49 5.40 8.51 0.8 15.5 53.8 2.0 6.9 05/15/02 30 60 9 f n 29.11 27.87 4.26 6.63 0.5 12.0 51.9 2.4 10.3 05/15/02 60 90 9 f n 29.11 27.98 3.88 6.02 0.5 13.2 101.8 2.4 18.4 05/15/02 0 15 9 r n 29.15 28.10 3.60 5.34 4.0 111.0 116.2 8.9 9.3 05/15/02 15 30 9 r n 29.04 28.20 2.89 4.44 2.3 77.9 132.6 5.2 8.8 05/15/02 30 60 9 r n 29.28 28.13 3.93 6.09 3.9 99.0 118.4 18.1 21.6 05/15/02 60 90 9 r n 29.39 28.22 3.98 6.18 4.8 119.6 118.2 22.2 21.9 05/15/02 0 15 10 f n 29.26 27.83 4.89 7.35 3.7 75.1 175.9 8.3 19.4 05/15/02 15 30 10 f n 29.09 27.42 5.74 9.07 0.9 15.5 73.9 2.1 10.1 05/15/02 30 60 10 f n 29.21 27.81 4.79 7.50 0.6 12.9 70.4 2.9 15.8 05/15/02 60 90 10 f n 29.16 27.96 4.12 6.39 0.4 9.8 48.1 1.9 9.2 05/15/02 0 15 10 r n 28.85 27.94 3.15 4.66 10.4 330.7 48.0 23.1 3.4 05/15/02 15 30 10 r n 28.90 27.93 3.36 5.17 70.5 2100.8 183.5 163.1 14.2 05/15/02 30 60 10 r n 29.02 27.87 3.96 6.15 20.5 518.3 82.2 95.6 15.2 05/15/02 60 90 10 r n 29.30 28.01 4.40 6.86 7.9 180.0 55.5 37.0 11.4 05/15/02 0 15 11 f n 29.60 28.01 5.37 8.12 1.2 22.7 36.8 2.8 4.5 05/15/02 15 30 11 f n 29.29 27.89 4.78 7.48 0.5 10.7 98.5 1.2 11.0 05/15/02 30 60 11 f n 29.57 28.19 4.67 7.29 0.4 8.6 107.1 1.9 23.4 05/15/02 60 90 11 f n 29.05 27.77 4.41 6.87 0.3 6.6 73.9 1.4 15.2 05/15/02 0 15 11 r n 28.99 27.91 3.73 5.53 1.9 51.7 176.2 4.3 14.6 05/15/02 15 30 11 r n 29.85 28.94 3.05 4.69 3.9 127.6 103.0 9.0 7.2 05/15/02 30 60 11 r n 29.55 28.26 4.37 6.80 2.9 66.6 42.7 13.6 8.7 05/15/02 60 90 11 r n 29.02 27.77 4.31 6.71 5.0 115.6 67.5 23.3 13.6 05/15/02 0 15 3 f n 29.21 27.61 5.48 8.29 0.8 14.3 81.7 1.8 10.2 05/15/02 15 30 3 f n 29.18 27.43 6.00 9.51 0.5 7.6 69.8 1.1 9.9 05/15/02 30 60 3 f n 29.47 27.72 5.94 9.41 0.5 7.7 64.6 2.2 18.2 05/15/02 60 90 3 f n 29.07 27.64 4.92 7.71 0.3 5.9 73.4 1.4 17.0 05/15/02 0 15 3 r n 29.21 27.82 4.76 7.14 2.8 58.8 52.6 6.3 5.6 05/15/02 15 30 3 r n 28.89 27.68 4.19 6.51 1.2 29.1 51.4 2.8 5.0 05/15/02 30 60 3 r n 29.33 27.73 5.46 8.60 0.3 5.4 38.4 1.4 9.9 05/15/02 60 90 3 r n 29.98 28.41 5.24 8.23 0.3 5.6 36.7 1.4 9.1 05/22/02 0 15 12 f s 29.43 27.90 5.20 7.84 2.7 51.8 58.2 6.1 6.8 05/22/02 15 30 12 f s 29.55 28.03 5.14 8.08 2.4 46.0 110.7 5.6 13.4 05/22/02 30 60 12 f s 29.59 28.19 4.73 7.40 0.7 15.4 70.0 3.4 15.5 05/22/02 60 90 12 f s 29.66 28.24 4.79 7.49 0.4 8.4 53.5 1.9 12.0 05/22/02 0 15 12 r s 29.59 28.84 2.53 3.72 5.8 228.7 155.9 12.8 8.7 05/22/02 15 30 12 r s 29.53 28.92 2.07 3.14 19.4 941.5 798.6 44.4 37.6 05/22/02 30 60 12 r s 29.11 28.06 3.61 5.58 15.4 425.9 220.6 71.2 36.9 05/22/02 60 90 12 r s 29.45 28.41 3.53 5.45 3.2 91.6 49.5 15.0 8.1 05/22/02 0 15 13 f s 29.38 27.31 7.05 10.84 3.4 48.2 38.8 7.8 6.3 05/22/02 15 30 13 f s 29.05 27.07 6.82 10.90 4.3 63.5 384.0 10.4 62.8 05/22/02 30 60 13 f s 29.16 27.71 4.97 7.80 0.7 14.7 46.8 3.4 10.9 05/22/02 60 90 13 f s 29.86 28.48 4.62 7.22 0.4 8.7 36.5 1.9 7.9 05/22/02 0 15 13 r s 29.96 28.00 6.54 10.01 2.4 37.0 40.0 5.6 6.0 05/22/02 15 30 13 r s 29.32 28.17 3.92 6.08 14.0 356.9 65.2 32.6 6.0

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133 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/22/02 30 60 13 r s 29.03 27.52 5.20 8.18 5.5 106.2 49.2 26.1 12.1 05/22/02 60 90 13 r s 29.09 27.63 5.02 7.87 1.5 29.7 39.4 7.0 9.3 05/22/02 0 15 6 f s 29.33 27.42 6.51 9.96 1.6 24.6 38.4 3.7 5.7 05/22/02 15 30 6 f s 29.95 28.23 5.74 9.08 1.5 26.0 70.8 3.5 9.6 05/22/02 30 60 6 f s 29.39 27.78 5.48 8.64 0.5 9.3 84.9 2.4 22.0 05/22/02 60 90 6 f s 29.91 28.79 3.74 5.80 0.3 7.8 74.5 1.4 13.0 05/22/02 0 15 6 r s 29.29 28.04 4.27 6.37 3.0 70.7 96.7 6.8 9.2 05/22/02 15 30 6 r s 29.58 28.57 3.41 5.27 13.5 394.0 105.6 31.1 8.3 05/22/02 30 60 6 r s 29.44 28.20 4.21 6.55 2.1 50.9 63.5 10.0 12.5 05/22/02 60 90 6 r s 29.02 27.69 4.58 7.16 1.5 32.5 55.8 7.0 12.0 05/22/02 0 15 7 f s 29.47 27.76 5.80 8.81 1.8 30.4 46.1 4.0 6.1 05/22/02 15 30 7 f s 29.56 27.92 5.55 8.75 1.0 18.0 47.2 2.4 6.2 05/22/02 30 60 7 f s 29.68 28.58 3.71 5.73 0.4 10.8 145.8 1.9 25.1 05/22/02 60 90 7 f s 29.82 28.51 4.39 6.85 0.3 7.9 82.0 1.6 16.9 05/22/02 0 15 7 r s 29.90 28.88 3.41 5.05 6.6 193.9 134.6 14.7 10.2 05/22/02 15 30 7 r s 29.40 28.52 2.99 4.60 18.9 631.6 285.3 43.6 19.7 05/22/02 30 60 7 r s 29.62 28.50 3.78 5.86 4.4 115.8 44.7 20.3 7.8 05/22/02 60 90 7 r s 29.96 28.76 4.01 6.22 3.9 97.1 90.0 18.1 16.8 05/22/02 0 15 4 f s 29.78 28.16 5.44 8.23 2.7 50.5 51.3 6.2 6.3 05/22/02 15 30 4 f s 29.73 28.19 5.18 8.14 1.9 36.2 52.8 4.4 6.4 05/22/02 30 60 4 f s 29.11 27.83 4.40 6.85 0.5 11.6 50.3 2.4 10.3 05/22/02 60 90 4 f s 29.63 28.36 4.29 6.67 0.5 10.6 97.6 2.1 19.5 05/22/02 0 15 4 r s 29.35 28.67 2.32 3.39 6.6 285.5 125.5 14.5 6.4 05/22/02 15 30 4 r s 29.36 28.67 2.35 3.59 12.9 549.3 148.4 29.5 8.0 05/22/02 30 60 4 r s 29.94 28.98 3.21 4.94 6.0 185.9 61.7 27.5 9.1 05/22/02 60 90 4 r s 29.07 27.92 3.96 6.14 5.5 138.3 58.8 25.5 10.8 05/29/02 0 15 8 f n 29.28 27.99 4.41 6.59 1.1 24.8 56.8 2.5 5.6 05/29/02 15 30 8 f n 29.06 27.75 4.51 7.03 0.5 12.0 80.0 1.3 8.4 05/29/02 30 60 8 f n 29.62 28.44 3.98 6.18 0.9 21.9 115.2 4.1 21.4 05/29/02 60 90 8 f n 28.84 27.48 4.72 7.37 0.5 11.5 71.5 2.5 15.8 05/29/02 0 15 8 r n 28.93 27.88 3.63 5.39 5.1 141.7 70.5 11.4 5.7 05/29/02 15 30 8 r n 29.71 29.23 1.62 2.45 7.6 469.4 870.2 17.2 31.9 05/29/02 30 60 8 r n 29.58 28.59 3.35 5.16 4.0 120.5 97.3 18.7 15.1 05/29/02 60 90 8 r n 28.91 27.53 4.77 7.47 13.0 271.5 75.5 60.8 16.9 05/29/02 0 15 9 f n 29.80 28.58 4.09 6.10 0.9 22.7 61.1 2.1 5.6 05/29/02 15 30 9 f n 29.74 28.70 3.50 5.40 1.2 32.9 103.1 2.7 8.3 05/29/02 30 60 9 f n 29.46 28.44 3.46 5.34 0.8 22.0 260.0 3.5 41.7 05/29/02 60 90 9 f n 29.57 28.42 3.89 6.03 0.3 8.2 53.9 1.5 9.7 05/29/02 0 15 9 r n 29.61 28.76 2.87 4.23 4.6 161.8 73.0 10.3 4.6 05/29/02 15 30 9 r n 29.35 28.61 2.52 3.85 4.2 166.6 92.3 9.6 5.3 05/29/02 30 60 9 r n 29.19 28.08 3.80 5.89 2.6 68.2 45.9 12.0 8.1 05/29/02 60 90 9 r n 29.06 27.84 4.20 6.53 1.3 31.4 69.3 6.1 13.6 05/29/02 0 15 10 f n 29.05 27.85 4.13 6.16 2.4 57.4 98.5 5.3 9.1 05/29/02 15 30 10 f n 29.19 28.19 3.43 5.29 2.9 83.8 120.5 6.6 9.6 05/29/02 30 60 10 f n 28.92 27.70 4.22 6.56 1.0 24.6 82.7 4.9 16.3 05/29/02 60 90 10 f n 29.52 28.26 4.27 6.64 0.9 20.5 85.8 4.1 17.1 05/29/02 0 15 10 r n 29.08 27.29 6.16 9.38 19.1 309.7 317.1 43.6 44.6 05/29/02 15 30 10 r n 29.05 28.24 2.79 4.27 18.2 653.9 272.9 41.9 17.5 05/29/02 30 60 10 r n 29.10 28.17 3.20 4.92 10.2 318.4 163.6 47.0 24.1 05/29/02 60 90 10 r n 29.39 28.22 3.98 6.18 4.8 119.5 118.2 22.1 21.9 05/29/02 0 15 11 f n 29.29 28.11 4.03 6.00 11.7 291.2 150.0 26.2 13.5 05/29/02 15 30 11 f n 29.78 28.83 3.19 4.91 3.6 114.3 214.9 8.4 15.8 05/29/02 30 60 11 f n 29.55 28.58 3.28 5.06 1.6 50.2 102.7 7.6 15.6 05/29/02 60 90 11 f n 29.60 28.46 3.85 5.97 0.5 14.0 40.8 2.5 7.3 05/29/02 0 15 11 r n 29.48 28.47 3.43 5.07 6.5 190.6 117.1 14.5 8.9 05/29/02 15 30 11 r n 29.25 28.16 3.73 5.77 8.7 233.3 93.6 20.2 8.1 05/29/02 30 60 11 r n 29.32 28.29 3.51 5.42 18.2 519.0 109.2 84.5 17.8 05/29/02 60 90 11 r n 29.44 28.29 3.91 6.06 3.7 94.8 53.6 17.2 9.7 05/29/02 0 15 3 f n 29.67 28.32 4.55 6.82 1.1 24.1 38.4 2.5 3.9

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134 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 05/29/02 15 30 3 f n 29.41 28.28 3.84 5.95 1.0 25.6 33.4 2.3 3.0 05/29/02 30 60 3 f n 29.52 28.32 4.07 6.31 0.6 14.7 37.2 2.8 7.1 05/29/02 60 90 3 f n 29.74 28.59 3.87 5.99 0.5 12.5 57.2 2.3 10.3 05/29/02 0 15 3 r n 29.54 28.36 3.99 5.95 1.9 46.8 58.3 4.2 5.2 05/29/02 15 30 3 r n 29.34 28.54 2.73 4.18 2.2 80.8 115.2 5.1 7.2 05/29/02 30 60 3 r n 29.53 28.42 3.76 5.82 1.0 27.7 60.4 4.8 10.5 05/29/02 60 90 3 r n 29.85 28.63 4.09 6.35 0.5 11.9 135.1 2.3 25.7 06/05/02 0 15 12 f s 29.22 27.78 4.93 7.41 6.0 122.2 60.1 13.6 6.7 06/05/02 15 30 12 f s 29.24 27.75 5.10 8.00 2.3 45.4 55.8 5.4 6.7 06/05/02 30 60 12 f s 29.80 28.36 4.83 7.57 0.8 16.9 78.0 3.8 17.7 06/05/02 60 90 12 f s 29.37 28.21 3.95 6.13 0.7 16.5 36.9 3.0 6.8 06/05/02 0 15 12 r s 29.20 28.39 2.77 4.08 9.9 358.5 148.4 21.9 9.1 06/05/02 15 30 12 r s 29.54 28.54 3.39 5.22 9.5 280.7 373.0 22.0 29.2 06/05/02 30 60 12 r s 29.54 28.17 4.64 7.25 9.7 209.6 66.3 45.6 14.4 06/05/02 60 90 12 r s 29.57 28.21 4.60 7.18 5.1 110.5 34.2 23.8 7.4 06/05/02 0 15 13 f s 29.18 27.81 4.69 7.04 6.5 138.9 58.1 14.7 6.1 06/05/02 15 30 13 f s 28.96 27.63 4.59 7.17 2.2 48.0 64.5 5.2 6.9 06/05/02 30 60 13 f s 29.00 27.81 4.10 6.38 0.8 20.0 53.8 3.8 10.3 06/05/02 60 90 13 f s 29.46 28.32 3.87 6.00 0.8 19.7 58.6 3.5 10.5 06/05/02 0 15 13 r s 29.47 28.60 2.95 4.35 11.5 389.9 206.0 25.4 13.4 06/05/02 15 30 13 r s 29.35 28.44 3.10 4.77 8.7 281.9 173.8 20.2 12.4 06/05/02 30 60 13 r s 29.12 27.89 4.22 6.57 3.5 83.6 50.9 16.5 10.0 06/05/02 60 90 13 r s 29.80 28.62 3.96 6.14 3.3 83.6 42.6 15.4 7.9 06/05/02 0 15 6 f s 28.92 27.62 4.50 6.73 4.1 92.1 50.4 9.3 5.1 06/05/02 15 30 6 f s 29.16 27.97 4.08 6.34 2.3 56.7 45.6 5.4 4.3 06/05/02 30 60 6 f s 29.65 28.49 3.91 6.07 0.9 22.3 55.0 4.1 10.0 06/05/02 60 90 6 f s 29.10 28.05 3.61 5.58 0.7 19.6 94.9 3.3 15.9 06/05/02 0 15 6 r s 29.18 28.58 2.06 3.00 9.3 454.6 228.3 20.5 10.3 06/05/02 15 30 6 r s 29.01 28.24 2.65 4.06 8.9 335.4 218.2 20.4 13.3 06/05/02 30 60 6 r s 29.49 28.57 3.12 4.80 4.5 145.2 65.2 20.9 9.4 06/05/02 60 90 6 r s 29.59 28.51 3.65 5.64 2.9 78.6 41.5 13.3 7.0 06/05/02 0 15 7 f s 28.96 27.67 4.45 6.67 3.4 76.8 162.5 7.7 16.2 06/05/02 15 30 7 f s 29.08 27.85 4.23 6.58 1.5 36.4 82.3 3.6 8.1 06/05/02 30 60 7 f s 29.06 27.85 4.16 6.47 0.7 15.7 93.3 3.0 18.1 06/05/02 60 90 7 f s 29.17 28.03 3.91 6.06 0.5 13.9 29.9 2.5 5.4 06/05/02 0 15 7 r s 29.17 28.63 1.85 2.70 14.3 771.3 528.4 31.2 21.4 06/05/02 15 30 7 r s 29.00 27.44 5.38 8.47 17.6 327.2 226.1 41.6 28.7 06/05/02 30 60 7 r s 29.59 28.59 3.38 5.21 17.6 520.8 294.6 81.4 46.1 06/05/02 60 90 7 r s 29.78 28.74 3.49 5.39 3.6 104.3 78.1 16.9 12.6 06/05/02 0 15 4 f s 29.00 27.40 5.52 8.35 5.0 90.1 31.7 11.3 4.0 06/05/02 15 30 4 f s 28.99 27.00 6.86 10.98 3.6 53.1 24.6 8.7 4.1 06/05/02 30 60 4 f s 29.04 27.45 5.48 8.63 1.4 26.1 64.6 6.8 16.7 06/05/02 60 90 4 f s 29.14 27.68 5.01 7.86 1.1 21.9 42.9 5.2 10.1 06/05/02 0 15 4 r s 29.40 28.67 2.48 3.64 10.5 422.8 170.4 23.1 9.3 06/05/02 15 30 4 r s 29.49 28.40 3.70 5.72 4.2 113.2 61.3 9.7 5.3 06/05/02 30 60 4 r s 28.99 27.61 4.76 7.45 7.4 155.6 57.3 34.8 12.8 06/05/02 60 90 4 r s 29.20 27.99 4.14 6.44 5.4 130.7 77.0 25.3 14.9 06/12/02 0 15 8 r n 29.04 27.27 6.10 9.28 17.6 288.8 37.2 40.2 5.2 06/12/02 15 30 8 r n 29.01 27.52 5.14 8.07 8.9 173.4 52.0 21.0 6.3 06/12/02 30 60 8 r n 29.33 27.80 5.22 8.20 3.1 59.2 18.0 14.6 4.4 06/12/02 60 90 8 r n 28.95 27.52 4.94 7.74 5.2 105.1 50.6 24.4 11.7 06/12/02 0 15 9 r n 29.75 28.08 5.61 8.50 9.6 171.4 65.1 21.9 8.3 06/12/02 15 30 9 r n 29.06 27.39 5.75 9.08 3.8 65.3 45.5 8.9 6.2 06/12/02 30 60 9 r n 29.62 27.98 5.54 8.73 2.2 39.8 42.0 10.4 11.0 06/12/02 60 90 9 r n 29.71 28.14 5.28 8.31 1.0 18.6 37.4 4.6 9.3 06/12/02 0 15 10 r n 29.12 27.01 7.25 11.17 14.8 204.7 75.1 34.3 12.6 06/12/02 15 30 10 r n 29.18 27.68 5.14 8.07 6.9 133.3 43.0 16.2 5.2 06/12/02 30 60 10 r n 29.02 27.41 5.55 8.75 3.0 54.7 36.7 14.4 9.6 06/12/02 60 90 10 r n 29.42 27.94 5.03 7.89 5.7 113.1 32.4 26.8 7.7

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135 Table A-1. Continued Date Depth (cm) Well FurrowRow Half wet wtdry wt % (mass) %q (vol) ug NO3N/gm wet soil mg NO3N/L mg NH4N/L kg N/haNO3 kg N/haNH4 06/12/02 0 15 11 r n 29.39 27.54 6.29 9.61 10.4 165.2 46.1 23.8 6.6 06/12/02 15 30 11 r n 29.72 28.01 5.75 9.10 4.8 83.5 35.4 11.4 4.8 06/12/02 30 60 11 r n 29.76 28.08 5.65 8.91 2.2 39.0 43.2 10.4 11.6 06/12/02 60 90 11 r n 29.04 27.56 5.10 8.00 1.2 23.7 34.3 5.7 8.2 06/12/02 0 15 3 r n 29.76 27.97 6.01 9.15 10.5 173.8 36.7 23.9 5.0 06/12/02 15 30 3 r n 29.39 27.83 5.31 8.35 3.5 66.5 41.6 8.3 5.2 06/12/02 30 60 3 r n 29.61 27.99 5.47 8.62 1.4 25.1 34.1 6.5 8.8 06/12/02 60 90 3 r n 29.61 28.16 4.90 7.67 1.0 20.1 40.4 4.6 9.3

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APPENDIX B PLANT SAMPLE ANALYSIS RESULTS

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137 Table B-1. Potato crop analysis results (2001) Date DAP Location Tissue Type LA Total Fresh Weight Total Dry Weight Moisture Content TKN N Mass per sample Plant N per area cm2 g/area sampled g/plant % mg/kg mg/plant kg N/ha 03/24/01 37 Well 10 Leaves 873.70 32.37 4.58 0.859 58400 267.472 9.64 03/24/01 37 Well 10 Stems 38.69 2.87 0.926 38200 109.634 03/24/01 37 Well 10 Tubers 3.9 0.5 0.872 36000 18 03/24/01 37 Well 10 Leaves 525.51 16.78 2.32 0.862 67300 156.136 5.88 03/24/01 37 Well 10 Stems 22.43 2.16 0.904 38400 82.944 03/24/01 37 Well 10 Tubers 0.69 0.06 0.913 37000 2.22 03/24/01 37 Well 8 Leaves 935.61 30.03 3.91 0.870 52000 203.32 7.80 03/24/01 37 Well 8 Stems 46.62 3.06 0.934 35600 108.936 03/24/01 37 Well 8 Tubers 1.81 0.21 0.884 36000 7.56 03/24/01 37 Well 8 Leaves 641.08 20.09 2.76 0.863 70200 193.752 7.51 03/24/01 37 Well 8 Stems 36.66 2.99 0.918 37400 111.826 03/24/01 37 Well 8 Tubers 0.45 0.06 0.867 38300 2.298 03/24/01 37 Well 6 Leaves 592.50 19.55 2.52 0.871 64500 162.54 5.66 03/24/01 37 Well 6 Stems 28.11 1.78 0.937 38000 67.64 03/24/01 37 Well 6 Tubers 0.45 0.04 0.911 46800 1.872 03/24/01 37 Well6 Leaves 1039.92 36.28 4.59 0.873 56600 259.794 8.65 03/24/01 37 Well6 Stems 54.53 3.26 0.940 27400 89.324 03/24/01 37 Well6 Tubers 2.26 0.26 0.885 20800 5.408 03/24/01 37 SE corner Leaves 725.96 23.13 2.75 0.881 64700 177.925 6.13 03/24/01 37 SE corner Stems 32.34 1.93 0.940 37200 71.796 03/24/01 37 SE corner Tubers 1.23 0.13 0.894 11200 1.456 03/24/01 37 SE corner Leaves 618.52 17.31 2.4 0.861 66600 159.84 7.06 03/24/01 37 SE corner Stems 41.82 3.54 0.915 36000 127.44 03/24/01 37 SE corner Tubers 0.61 0.06 0.902 39700 2.382 03/27/01 40 Well 4 Leaves 846.70 26.03 5.32 0.796 44800 238.336 8.31 03/27/01 40 Well 4 Stems 43.47 3.96 0.909 20700 81.972 03/27/01 40 Well 4 Tubers 4.16 0.84 0.798 24200 20.328 03/27/01 40 Well 4 Leaves 804.50 24.9 4.38 0.824 51400 225.132 8.56 03/27/01 40 Well 4 Stems 41.18 3.5 0.915 26000 91 03/27/01 40 Well 4 Tubers 6.97 1.56 0.776 22400 34.944 04/03/01 47 Well 8 Leaves 2056.17 74.92 7.46 0.900 57200 426.712 16.93 04/03/01 47 Well 8 Stems 79.7 4.33 0.946 28900 125.137 04/03/01 47 Well 8 Tubers 39.41 5.47 0.861 26000 142.22 04/03/01 47 Well 6 Leaves 1200.33 39.99 4.21 0.895 57600 242.496 9.90 04/03/01 47 Well 6 Stems 50.72 3.15 0.938 31200 98.28 04/03/01 47 Well 6 Tubers 18.98 2.78 0.854 23400 65.052 04/03/01 47 Well 8 Leaves 979.91 34.22 4.25 0.876 59200 251.6 9.68 04/03/01 47 Well 8 Stems 49.69 3 0.940 33400 100.2 04/03/01 47 Well 8 Tubers 11.19 1.75 0.844 25800 45.15 04/03/01 47 Well 6 Leaves 2416.31 88.93 9.27 0.896 50000 463.5 18.64 04/03/01 47 Well 6 Stems 74.87 4.33 0.942 25200 109.116 04/03/01 47 Well 6 Tubers 58.93 8.64 0.853 22200 191.808 04/03/01 47 near W12 Leaves 1153.75 38.86 4.43 0.886 49100 217.513 9.41 04/03/01 47 near W12 Stems 37.41 2.29 0.939 29200 66.868 04/03/01 47 near W12 Tubers 31.9 4.98 0.844 20400 101.592 04/03/01 47 near W12 Leaves 1864.10 66.66 7.94 0.881 53200 422.408 15.76 04/03/01 47 near W12 Stems 75.2 5.12 0.932 29200 149.504 04/03/01 47 near W12 Tubers 19.98 2.93 0.853 25400 74.422 04/03/01 47 Well 10 Leaves 1384.06 45.15 5.32 0.882 58400 310.688 11.60 04/03/01 47 Well 10 Stems 53.47 3.35 0.937 27800 93.13 04/03/01 47 Well 10 Tubers 21.11 3.35 0.841 21400 71.69 04/03/01 47 Well 10 Leaves 2118.64 70.5 2.94 0.958 48000 141.12 11.69 04/03/01 47 Well 10 Stems 88.32 5.03 0.943 30200 151.906 04/03/01 47 Well 10 Tubers 20.05 7.77 0.612 24000 186.48 05/04/01 78 Well 8 Leaves 5447.30 204.22 26.34 0.871 24300 640.062 52.59 05/04/01 78 Well 8 Stems 105.76 7.98 0.925 18600 148.428 05/04/01 78 Well 8 Tubers 620.04 113.99 0.816 12000 1367.88

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138 Table B-1. Continued Date DAP Location Tissue Type LA Total Fresh Weight Total Dry Weight Moisture Content TKN N Mass per sample Plant N per area cm2 g/area sampled g/plant % mg/kg mg/plant kg N/ha 05/04/01 78 Well 6 Leaves 2461.60 83.92 8.72 0.896 35600 310.432 25.87 05/04/01 78 Well 6 Stems 77.25 4.18 0.946 16400 68.552 05/04/01 78 Well 6 Tubers 287.22 49.76 0.827 13700 681.712 05/04/01 78 Well 11 Leaves 6561.84 244.21 37.6 0.846 35800 1346.08 80.27 05/04/01 78 Well 11 Stems 158.98 11.88 0.925 20000 237.6 05/04/01 78 Well 11 Tubers 874.03 161.1 0.816 10600 1707.66 05/04/01 78 Well 10 Leaves 7138.00 272.2 37.62 0.862 23800 895.356 59.73 05/04/01 78 Well 10 Stems 266.35 15.82 0.941 17800 281.596 05/04/01 78 Well 10 Tubers 730.88 124.72 0.829 10200 1272.144 05/04/01 78 Well 7 Leaves 2109.90 72.95 7.57 0.896 46300 350.491 24.88 05/04/01 78 Well 7 Stems 37.18 2.66 0.928 21600 57.456 05/04/01 78 Well 7 Tubers 271.4 46.38 0.829 13200 612.216 05/04/01 78 Well 4 Leaves 2310.60 75.88 10.75 0.858 45400 488.05 30.28 05/04/01 78 Well 4 Stems 65.4 5.45 0.917 19900 108.455 05/04/01 78 Well 4 Tubers 306.3 49.64 0.838 13000 645.32 05/04/01 78 Well 12 Leaves 4185.80 155.22 19.42 0.875 31800 617.556 53.52 05/04/01 78 Well 12 Stems 109.6 7.52 0.931 20000 150.4 05/04/01 78 Well 12 Tubers 573.6 104.89 0.817 13600 1426.504 05/04/01 78 Well 9 Leaves 1554.80 58.77 6.62 0.887 38700 256.194 19.48 05/04/01 78 Well 9 Stems 55.7 3.81 0.932 20700 78.867 05/04/01 78 Well 9 Tubers 213.08 38.63 0.819 12000 463.56 Table B-2. Potato crop analysis results (2002) Date DAP Well Half Tissue Type Area Sampled LA Total Fresh Weight Moisture Content Total Dry Weight TKN N Mass per sample Plant N per area cm2 cm2 g/area sampled % g/area sampled mg/kg mg/area sampled kg N/ha 4/3/2002 47 11 N stem 1 plant 120.0 0.95 6.50 41300 268.5 24.75 4/3/2002 47 11 N tuber 1 plant 12.7 0.85 1.90 21000 39.9 4/3/2002 47 11 N leaves 1 plant 2336 82.5 0.87 10.40 67950 706.7 4/3/2002 47 3 N tuber 1 plant 12.0 0.83 2.00 23050 46.1 21.64 4/3/2002 47 3 N tuber 1 plant 8.6 0.85 1.30 22050 28.7 4/3/2002 47 3 N leaves 1 plant 2186 71.9 0.87 9.50 60700 576.7 4/3/2002 47 3 N leaves 1 plant 2636 86.2 0.85 12.70 60650 770.3 26.23 4/3/2002 47 3 N stem 1 plant 97.6 0.93 6.60 40100 264.7 4/3/2002 47 3 N stem 1 plant 105.6 0.93 7.00 39500 276.5 4/3/2002 47 8 N leaves 1 plant 1830 64.2 0.82 11.40 64150 731.3 22.19 4/3/2002 47 8 N leaves 1 plant 2109 78.1 0.82 13.80 64150 885.3 4/3/2002 47 8 N stem 1 plant 55.0 0.92 4.20 36700 154.1 4/3/2002 47 8 N stem 1 plant 81.7 0.92 6.30 31350 197.5 26.41 4/3/2002 47 8 N tuber 1 plant 6.3 0.87 0.80 30500 24.4 4/3/2002 47 9 N leaves 1 plant 2123 80.1 0.86 11.20 63950 716.2 21.85 4/3/2002 47 9 N leaves 1 plant 1491 50.2 0.87 6.70 66150 443.2 4/3/2002 47 9 N stem 1 plant 63.6 0.94 4.10 39350 161.3 4/3/2002 47 9 N stem 1 plant 87.9 0.94 5.70 36550 208.3 16.21 4/3/2002 47 9 N tuber 1 plant 4.8 0.86 0.70 26150 18.3 4/3/2002 47 9 N tuber 1 plant 3.7 0.86 0.50 26150 13.1 4/12/2002 56 4 S leaves 90x90 1225 275.1 0.86 37.62 43540 1637.9 27.55 4/12/2002 56 4 S stem 90x90 253.3 0.92 20.36 14600 297.3 4/12/2002 56 4 S tuber 90x90 260.4 0.91 23.72 12500 296.6 4/12/2002 56 13 S leaves 90x90 1240 645.2 0.86 89.95 58600 5270.8 79.28 4/12/2002 56 13 S stem 90x90 717.7 0.96 32.07 26600 853.1 4/12/2002 56 13 S tuber 90x90 241.0 0.94 14.03 21200 297.4 4/24/2002 68 7 S leaves 45x90 2031 483.4 0.88 57.48 54450 3129.7 142.06 4/24/2002 68 7 S stem 45x90 502.2 0.93 35.02 23800 833.4 4/24/2002 68 7 S tuber 45x90 923.7 0.87 120.15 14900 1790.2

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139 Table B-2. Continued Date DAP Well Half Tissue Type Area Sampled LA Total Fresh Weight Moisture Content Total Dry Weight TKN N Mass per sample Plant N per area cm2 cm2 g/area sampled % g/area sampled mg/kg mg/area sampled kg N/ha 4/24/2002 68 11 N leaves 45x90 425.1 0.82 77.99 45550 3552.5 213.43 4/24/2002 68 11 N stem 45x90 466.7 0.93 30.67 26100 800.5 4/24/2002 68 11 N tuber 45x90 1056.5 0.85 160.21 14150 2266.9 4/24/2002 68 11 N leaves 45x90 447.6 0.86 64.46 44650 2878.2 198.30 4/24/2002 68 11 N stem 45x90 554.1 0.95 27.71 23550 652.5 4/24/2002 68 11 N tuber 45x90 1007.5 0.85 153.60 14250 2188.8 4/24/2002 68 4 S leaves 45x90 658.0 0.83 111.78 36700 4102.2 166.50 4/24/2002 68 4 S stem 45x90 668.9 0.92 52.40 22200 1163.3 4/24/2002 68 4 S tuber 45x90 1224.4 0.85 183.08 15500 2837.8 5/6/2002 80 6 S leaves 90x90 1084.0 0.88 128.29 37350 4791.5 146.10 5/6/2002 80 6 S stem 90x90 931.0 0.93 65.34 16950 1107.6 5/6/2002 80 6 S tuber 90x90 2881.7 0.85 435.86 13600 5927.6 5/6/2002 80 7 S leaves 90x90 633.9 0.85 95.57 31600 3019.9 163.46 5/6/2002 80 7 S stem 90x90 609.4 0.92 46.28 17000 786.8 5/6/2002 80 7 S tuber 90x90 1912.6 0.84 297.52 12100 3599.9 5/6/2002 80 12 S leaves 90x90 862.1 0.87 112.19 30600 3433.0 141.22 5/6/2002 80 12 S stem 90x90 872.1 0.93 58.08 17300 1004.7 5/6/2002 80 12 S tuber 90x90 2768.0 0.85 417.13 13550 5652.1 5/6/2002 80 8 N leaves 45x90 470.7 0.81 87.20 28650 2498.3 200.08 5/6/2002 80 8 N stem 45x90 579.9 0.93 43.49 22050 959.0 5/6/2002 80 8 N tuber 45x90 2111.1 0.83 355.26 14900 5293.4 5/6/2002 80 8 N leaves 45x90 411.6 0.86 58.54 30450 1782.5 153.25 5/6/2002 80 8 N stem 45x90 402.9 0.93 29.75 22950 682.8 5/6/2002 80 8 N tuber 45x90 1346.3 0.83 222.15 14650 3254.6 5/6/2002 80 4 S leaves 45x90 418.5 0.87 53.97 26550 1432.9 98.14 5/6/2002 80 4 S stem 45x90 375.7 0.91 33.85 14100 477.3 5/6/2002 80 4 S tuber 45x90 1405.8 0.83 246.00 9250 2275.5 5/6/2002 80 3 N leaves 45x90 207.1 0.88 24.78 33100 820.2 137.67 5/6/2002 80 3 N stem 45x90 203.1 0.92 16.47 22500 370.5 5/6/2002 80 3 N tuber 45x90 682.4 0.80 134.19 14775 1982.6 5/6/2002 80 10 N leaves 45x90 454.8 0.90 45.12 32717 1476.2 229.41 5/6/2002 80 10 N stem 45x90 481.5 0.94 28.97 22500 651.9 5/6/2002 80 10 N tuber 45x90 1428.9 0.85 207.59 14775 3067.2

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APPENDIX C SUBSTOR/DSSAT INPUT FILES

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141SUBSTOR Input File Created from DSSAT FILEX *MODEL INPUT FILE I 1 5 1 3 0 *FILES MODEL PTSUB980.EXE FILEX REDLASOD.PTX FILEA REDLASOD.PTA FILET REDLASOD.PTT SPECIES PTSUB980.SPE C:\DSSAT35\GENOTYPE\ ECOTYPE CULTIVAR PTSUB980.CUL C:\DSSAT35\GENOTYPE\ PESTS PTSUB980.PST C:\DSSAT35\PEST\ SOILS SOIL.SOL C:\DSSAT35\SOIL\ WEATHER UFSU0101.WTH C:\DSSAT35\WEATHER\ OUTPUT OVERVIEW *SIMULATION CONTROL 1 1 I 1001 2150 REDSODA1 Y Y N N N N N N M M E R R C R 1 U R R R N R N Y Y 1 Y N Y Y N Y Y N N !AUTOMATIC MANAGEM 1354 1354 40. 100. 30. 40. 10. 30. 50. 100. GS000 IR001 10.0 1.000 30. 50. 25. FE001 GS000 100. 1 20. 0 2354 100. 0. *EXP.DETAILS 5REDLASOD PT REDLASODPT *TREATMENTS 10 0 0 NORTHHALF *CULTIVARS PT UF0001 RED LASODA *FIELDS UFSW0001 UFSU0101 .0 0. DR000 0. 100. 00000 FSA 60. UF00850002 -83.04000 30.08000 13.70 99.0 995. 1.0 .0 *INITIAL CONDITIONS CO 01001 1. 0. 1.00 1.00 200.0 0 .00 .00 100. 15. 5. .084 3.2 5.3 15. .084 3.2 5.3 30. .094 3.2 5.3 45. .083 3.2 5.3 60. .083 3.1 2.5 90. .089 3.0 1.1 *PLANTING DETAILS 1046 1066 2.7 2.3 S R 90. 101. 16.0 1500. -99. -99.0 -99.0 5.0

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142*IRRIGATION .900 60. 50. 100. GS000 IR001 10.0 1007 IR004 5.0 0 1012 IR004 3.0 0 1013 IR004 5.0 0 1037 IR004 3.0 0 1043 IR004 7.0 0 1048 IR004 6.0 0 1051 IR004 5.0 0 1053 IR004 7.0 0 1055 IR004 9.0 0 1060 IR004 8.0 0 1066 IR004 4.0 0 1071 IR004 5.0 0 1083 IR004 9.0 0 1085 IR004 6.0 0 1091 IR004 8.0 0 1092 IR004 9.0 0 1093 IR004 8.0 0 1094 IR004 9.0 0 1095 IR004 8.0 0 1096 IR004 9.0 0 1097 IR004 8.0 0 1098 IR004 9.0 0 1099 IR004 8.0 0 1100 IR004 9.0 0 1101 IR004 8.0 0 1102 IR004 9.0 0 1103 IR004 8.0 0 1104 IR004 9.0 0 1105 IR004 8.0 0 1106 IR004 9.0 0 1107 IR004 8.0 0 1108 IR004 9.0 0 1109 IR004 8.0 0 1110 IR004 9.0 0 1111 IR004 8.0 0 1112 IR004 9.0 0 1113 IR004 8.0 0 1114 IR004 9.0 0 1115 IR004 8.0 0 1116 IR004 9.0 0 1117 IR004 8.0 0 1118 IR004 9.0 0 1119 IR004 8.0 0 1120 IR004 9.0 0 1121 IR004 8.0 0

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143 1122 IR004 9.0 0 1123 IR004 8.0 0 1124 IR004 9.0 0 1125 IR004 8.0 0 1126 IR004 9.0 0 1127 IR004 8.0 0 1128 IR004 9.0 0 1129 IR004 8.0 0 1130 IR004 9.0 0 1131 IR004 8.0 0 1132 IR004 9.0 0 1133 IR004 8.0 0 1134 IR004 9.0 0 1135 IR004 8.0 0 1136 IR004 9.0 0 1137 IR004 8.0 0 1138 IR004 9.0 0 1139 IR004 8.0 0 1140 IR004 9.0 0 *FERTILIZERS 1007 FE001 AP005 0. 1. 0. 0. 0. 0. 1012 FE001 AP005 0. 1. 0. 0. 0. 0. 1013 FE001 AP005 0. 1. 0. 0. 0. 0. 1018 FE001 AP009 15. 38. 0. 0. 0. 0. 1037 FE001 AP005 0. 1. 0. 0. 0. 0. 1043 FE001 AP005 0. 1. 0. 0. 0. 0. 1046 FE001 AP004 15. 17. 0. 0. 0. 0. 1048 FE001 AP005 0. 1. 0. 0. 0. 0. 1051 FE001 AP005 0. 1. 0. 0. 0. 0. 1053 FE001 AP005 0. 1. 0. 0. 0. 0. 1055 FE001 AP005 0. 2. 0. 0. 0. 0. 1060 FE001 AP005 0. 2. 0. 0. 0. 0. 1064 FE001 AP009 15. 112. 0. 0. 0. 0. 1066 FE001 AP005 0. 1. 0. 0. 0. 0. 1071 FE001 AP005 0. 1. 0. 0. 0. 0. 1083 FE001 AP005 0. 2. 0. 0. 0. 0. 1084 FE001 AP009 15. 112. 0. 0. 0. 0. 1091 FE001 AP005 0. 2. 0. 0. 0. 0. 1092 FE001 AP005 0. 2. 0. 0. 0. 0. 1093 FE001 AP005 0. 2. 0. 0. 0. 0. 1094 FE001 AP005 0. 2. 0. 0. 0. 0. 1095 FE001 AP005 0. 2. 0. 0. 0. 0. 1096 FE001 AP005 0. 2. 0. 0. 0. 0. 1097 FE001 AP005 0. 2. 0. 0. 0. 0. 1098 FE001 AP005 0. 2. 0. 0. 0. 0. 1099 FE001 AP005 0. 2. 0. 0. 0. 0. 1100 FE001 AP005 0. 2. 0. 0. 0. 0.

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144 1101 FE001 AP005 0. 2. 0. 0. 0. 0. 1102 FE001 AP005 0. 2. 0. 0. 0. 0. 1103 FE001 AP005 0. 2. 0. 0. 0. 0. 1104 FE001 AP005 0. 2. 0. 0. 0. 0. 1105 FE001 AP005 0. 2. 0. 0. 0. 0. 1106 FE001 AP005 0. 2. 0. 0. 0. 0. 1107 FE001 AP005 0. 2. 0. 0. 0. 0. 1108 FE001 AP005 0. 2. 0. 0. 0. 0. 1109 FE001 AP005 0. 2. 0. 0. 0. 0. 1110 FE001 AP005 0. 2. 0. 0. 0. 0. 1111 FE001 AP005 0. 2. 0. 0. 0. 0. 1112 FE001 AP005 0. 2. 0. 0. 0. 0. 1113 FE001 AP005 0. 34. 0. 0. 0. 0. 1114 FE001 AP005 0. 2. 0 0 0 0 1115 FE001 AP005 0. 2. 0. 0. 0. 0. 1116 FE001 AP005 0. 2. 0 0 0 0 1117 FE001 AP005 0. 2. 0. 0. 0. 0. 1118 FE001 AP005 0. 2. 0 0 0 0 1119 FE001 AP005 0. 2. 0. 0. 0. 0. 1120 FE001 AP005 0. 2. 0 0 0 0 1121 FE001 AP005 0. 2. 0. 0. 0. 0. 1122 FE001 AP005 0. 2. 0 0 0 0 1123 FE001 AP005 0. 2. 0. 0. 0. 0. 1124 FE001 AP005 0. 2. 0 0 0 0 1125 FE001 AP005 0. 2. 0. 0. 0. 0. 1126 FE001 AP005 0. 2. 0 0 0 0 1127 FE001 AP005 0. 2. 0. 0. 0. 0. 1128 FE001 AP005 0. 2. 0 0 0 0 1129 FE001 AP005 0. 2. 0. 0. 0. 0. 1130 FE001 AP005 0. 2. 0 0 0 0 1131 FE001 AP005 0. 2. 0. 0. 0. 0. 1132 FE001 AP005 0. 2. 0 0 0 0 1133 FE001 AP005 0. 2. 0. 0. 0. 0. 1134 FE001 AP005 0. 2. 0 0 0 0 1135 FE001 AP005 0. 2. 0. 0. 0. 0. 1136 FE001 AP005 0. 2. 0 0 0 0 1137 FE001 AP005 0. 2. 0. 0. 0. 0. 1138 FE001 AP005 0. 2. 0 0 0 0 1139 FE001 AP005 0. 2. 0. 0. 0. 0. 1140 FE001 AP005 0. 2. 0 0 0 0 *RESIDUES *CHEMICALS *TILLAGE *ENVIRONMENT *HARVEST 1141 GS000 L A 100. 0. *SOIL

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145 UF00850002 SCS FSA 60. TEMPLATE TEMPLATE USA -82.000 24.000 00 GROSSARENIC PALEUDULTS G .13 5.6 .50 75. 1.00 1.00 IB001 IB001 IB001 5. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 15. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 30. .017 .097 .388 .500 188.0 1.48 .02 1.2 3.7 1.1 -9.00 5.3 4.8 4.0 .0 45. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 60. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 90. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 5. .0 .0 .0 .0 .0 .0 .0 .0 15. .0 .0 .0 .0 .0 .0 .0 .0 30. .0 .0 .0 .0 .0 .0 .0 .0 45. .0 .0 .0 .0 .0 .0 .0 .0 60. .0 .0 .0 .0 .0 .0 .0 .0 90. .0 .0 .0 .0 .0 .0 .0 .0 *CULTIVAR UF0001 RED LASODA IB0001 2000. 22.0 .20 .7 .4 19.0

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146Cultivar File *POTATO GENOTYPE COEFFICIENTS PTSUB980 MODEL COEFF DEFINITIONS ======== =========== VAR# Identification code or number for a specific cultivar VAR-NAME Name of cultivar ECO# Ecotype code or this cultivar, points to the Ecotype in the ECO file (currently not used). G2 Leaf area expansion rate in degree days G3 Potential tuber growth rate G4 Currently not used in the model PD Index that supresses tuber growth during the period that immediately follows tuber induction P2 Index that relates photoperiod response to tuber initiation TC Upper critical temperature for tuber intitiation @VAR# VAR-NAME........ ECO# G2 G3 G4 PD P2 TC SW0001 REDLASOD IB0001 2000. 25.0 0.20 0.7 0.6 19.0 Soil File *POTATO GENOTYPE COEFFICIENTS PTSUB980 MODEL COEFF DEFINITIONS ======== =========== VAR# Identification code or number for a specific cultivar VAR-NAME Name of cultivar ECO# Ecotype code or this cultivar, points to the Ecotype in the ECO file (currently not used). G2 Leaf area expansion rate in degree days G3 Potential tuber growth rate G4 Currently not used in the model PD Index that supresses tuber growth during the period that immediately follows tuber induction P2 Index that relates photoperiod response to tuber initiation TC Upper critical temperature for tuber intitiation @VAR# VAR-NAME........ ECO# G2 G3 G4 PD P2 TC SW0001 REDLASOD IB0001 2000. 25.0 0.20 0.7 0.6 19.0 2001 Weather File *WEATHER DATA : SuwanneFarms,FL @ INSI LAT LONG ELEV TAV AMP REFHT WNDHT UFSU 29.000 -82.000 10 21.2 5.8 2.0 3.0 @DATE SRAD TMAX TMIN RAIN 01001 12.6 9.8 -4.9 0.0 01002 10.6 7.6 -3.4 0.0 01003 12.9 8.6 -6.3 0.0 01004 14.9 10.0 -5.9 0.9 01005 14.1 15.5 -5.2 0.0 01006 15.5 16.8 0.7 0.0 01007 14.7 18.9 -2.3 0.0 01008 10.2 19.3 7.7 2.9 01009 13.4 8.3 -2.4 0.0 01010 15.2 13.6 -5.7 0.0 01011 12.2 18.6 -1.4 4.4 01012 5.2 15.9 5.5 1.5 01013 13.2 17.2 2.4 0.0

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14701014 11.1 20.5 6.6 0.0 01015 9.7 23.6 5.6 0.1 01016 9.8 23.7 7.8 0.0 01017 8.8 23.8 11.6 0.0 01018 9.7 24.4 14.7 0.0 01019 10.4 25.5 15.1 4.3 01020 5.8 19.3 2.0 6.6 01021 15.0 10.6 -2.7 0.0 01022 14.1 12.7 -1.7 0.0 01023 15.3 15.0 1.2 0.1 01024 15.5 16.3 -0.3 0.0 01025 15.0 14.6 0.5 0.0 01026 16.5 15.6 -2.2 0.0 01027 12.4 20.8 0.4 0.0 01028 15.6 23.5 6.7 0.1 01029 12.3 21.6 8.0 0.1 01030 3.5 19.2 14.3 2.0 01031 2.0 15.7 12.4 8.7 01032 5.2 16.6 12.6 1.8 01033 4.8 12.8 8.9 1.2 01034 10.9 14.4 7.4 0.1 01035 8.6 14.4 6.2 5.0 01036 17.6 18.1 5.0 0.1 01037 17.5 21.4 0.4 0.1 01038 17.3 24.0 2.1 0.2 01039 17.5 25.8 6.2 0.0 01040 17.1 26.5 10.6 0.1 01041 6.1 22.4 11.5 0.9 01042 12.2 21.5 12.4 0.0 01043 12.0 21.6 11.6 0.0 01044 13.2 26.4 11.6 0.0 01045 13.5 26.2 14.1 0.0 01046 12.1 25.1 12.9 0.2 01047 11.8 25.5 14.9 0.2 01048 17.0 21.7 9.6 1.1 01049 19.7 20.4 4.4 0.0 01050 19.4 24.2 5.1 0.0 01051 11.0 24.5 10.0 0.0 01052 14.4 26.3 10.3 0.0 01053 15.3 25.0 12.1 0.8 01054 10.1 19.1 13.5 0.0 01055 12.7 26.7 11.4 0.0 01056 15.9 26.8 19.3 0.0 01057 14.7 26.3 18.4 0.0 01058 19.4 28.7 11.3 0.0 01059 17.3 26.6 13.1 1.6 01060 10.3 23.0 17.3 10.0 01061 14.3 26.4 19.0 0.0 01062 15.2 27.2 19.2 0.0 01063 12.0 23.5 14.3 16.4 01064 22.4 18.3 8.0 0.0 01065 22.9 15.5 5.1 0.0 01066 22.7 17.5 2.2 0.0 01067 22.7 19.3 0.2 0.0 01068 11.3 19.9 3.7 13.5 01069 22.2 20.3 7.6 0.0 01070 17.7 25.3 8.1 0.0

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14801071 16.7 27.5 12.7 0.0 01072 15.6 26.8 16.0 9.3 01073 17.9 24.7 12.3 0.8 01074 3.5 23.6 15.1 15.3 01075 19.9 25.3 13.0 6.4 01076 4.9 14.9 10.7 4.1 01077 3.5 12.2 9.6 19.1 01078 3.1 16.7 10.5 8.4 01079 14.6 17.5 8.2 8.4 01080 7.3 10.7 5.4 0.0 01081 24.9 21.4 5.7 0.0 01082 24.5 23.5 6.3 0.0 01083 24.2 25.4 6.5 0.0 01084 5.4 18.2 12.0 8.9 01085 25.4 18.0 6.6 0.1 01086 24.2 17.2 4.8 0.0 01087 20.6 21.3 4.8 0.0 01088 10.7 22.1 13.8 21.1 01089 12.6 23.8 15.7 1.2 01090 19.6 25.0 11.5 0.2 01091 25.6 24.2 9.5 0.0 01092 26.9 25.1 4.3 0.0 01093 22.9 25.4 9.8 0.0 01094 13.9 25.9 17.3 0.1 01095 20.4 26.2 15.8 0.0 01096 24.7 28.3 13.2 0.0 01097 22.4 28.7 14.8 0.0 01098 21.5 28.8 15.5 0.0 01099 22.4 28.5 17.2 0.1 01100 24.9 30.5 16.0 0.0 01101 19.8 28.6 17.0 0.0 01102 20.3 28.4 15.3 0.1 01103 22.3 28.0 17.3 0.1 01104 12.8 28.8 20.4 3.2 01105 23.9 28.4 20.6 5.9 01106 27.5 25.6 14.2 0.1 01107 26.4 24.1 10.5 0.0 01108 28.5 18.3 5.6 0.0 01109 27.7 22.7 3.2 0.0 01110 26.7 26.2 9.0 0.0 01111 25.7 27.7 12.8 0.0 01112 23.7 28.7 14.3 0.0 01113 26.0 29.3 15.1 0.0 01114 23.1 28.2 16.9 0.0 01115 10.4 22.3 15.5 5.6 01116 28.4 23.1 12.8 0.0 01117 28.9 26.6 6.6 0.0 01118 26.8 28.3 8.7 0.0 01119 25.8 27.7 12.4 0.0 01120 20.5 24.9 17.2 0.0 01121 24.4 27.7 14.2 0.0 01122 22.8 27.8 14.1 0.0 01123 24.2 28.1 16.5 0.0 01124 24.9 28.7 15.0 0.0 01125 25.7 29.9 14.0 0.0 01126 28.4 30.9 12.4 0.0 01127 12.8 23.7 16.6 1.8

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14901128 24.3 27.6 17.7 0.0 01129 18.1 27.8 13.0 2.6 01130 23.1 29.0 13.8 0.0 01131 27.0 30.1 13.4 0.0 01132 21.8 29.0 16.8 0.0 01133 26.1 29.9 16.6 0.0 01134 24.9 31.1 13.7 0.0 01135 24.0 30.5 18.0 0.0 01136 27.2 33.3 15.8 0.0 01137 26.6 33.3 18.1 0.0 01138 27.6 32.1 17.6 0.0 01139 28.5 31.7 14.7 0.0 01140 18.1 29.0 19.0 0.0 01141 28.7 31.8 17.8 0.0 01142 26.3 32.9 17.6 0.0 01143 27.0 28.6 16.1 0.0 01144 27.8 32.9 10.8 0.0 01145 12.2 31.9 18.3 0.0 01146 28.0 31.8 18.2 0.0 01147 26.8 32.6 15.8 0.0 01148 23.7 31.5 18.0 0.0 01149 15.6 28.4 20.4 0.0 01150 20.8 31.2 22.4 0.0 01151 25.3 33.5 19.7 0.0 01152 8.0 25.1 20.2 0.1 01153 26.2 30.5 19.9 0.1 01154 28.3 32.3 21.6 0.0 01155 24.6 34.7 22.1 0.0 01156 22.7 33.7 20.1 15.9 01157 20.0 30.3 20.2 0.0 01158 25.7 33.0 21.4 2.2 01159 14.7 30.1 22.7 5.0 01160 14.4 29.4 22.1 12.7 01161 8.2 25.8 22.0 0.7 01162 12.3 29.7 21.4 31.4 01163 12.8 28.3 23.3 25.4 01164 19.0 30.6 21.7 7.4 01165 18.7 31.0 21.1 0.0 01166 24.4 33.1 20.4 4.0 01167 16.2 32.1 21.9 0.0 01168 25.4 32.4 20.3 25.9 01169 15.1 30.7 21.4 8.9 01170 27.6 32.7 19.8 3.9 01171 22.7 32.1 20.1 10.7 01172 23.6 32.1 21.0 13.2 01173 19.1 29.8 20.9 22.7 01174 15.0 27.8 20.2 0.0 01175 28.8 30.6 19.7 0.0 01176 28.0 31.9 16.9 0.0 01177 28.6 33.5 18.0 0.3 01178 21.7 33.4 20.9 0.5 01179 18.5 30.8 21.2 30.7 01180 10.7 29.5 20.6 40.3 01181 22.6 31.8 20.2 58.0 01182 17.7 31.6 21.2 0.0 01183 17.2 31.2 21.6 0.0 01184 26.6 32.9 21.7 1.0

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15001185 16.0 31.2 22.6 1.1 01186 27.3 33.4 22.0 2.2 01187 20.9 31.1 21.6 0.0 01188 28.5 34.3 21.3 2.1 01189 22.9 34.2 24.6 0.0 01190 23.2 34.2 23.8 13.1 01191 17.7 32.6 23.9 28.1 01192 11.2 30.5 23.6 28.1 01193 20.4 30.7 23.9 0.5 01194 20.5 32.1 22.4 22.1 01195 21.3 30.2 22.8 1.2 01196 24.0 30.6 20.2 0.0 01197 21.6 31.1 19.3 0.0 01198 23.7 32.3 20.8 1.0 01199 20.3 31.5 21.8 0.3 01200 25.1 34.0 22.3 0.0 01201 17.0 34.4 22.6 0.0 01202 16.4 29.8 21.9 0.0 01203 21.8 31.3 23.4 0.0 01204 23.3 31.4 23.0 0.0 01205 7.6 26.5 22.4 0.0 01206 24.3 32.4 21.6 0.0 01207 26.5 30.7 21.8 3.4 01208 16.2 31.3 22.3 4.6 01209 27.2 33.0 21.0 0.0 01210 22.8 32.3 22.8 0.0 01211 20.7 32.8 22.8 13.8 01212 12.9 28.3 23.5 0.1 01213 18.0 30.7 22.0 5.3 01214 19.7 29.6 21.4 0.1 01215 21.6 30.1 20.8 0.9 01216 19.5 30.6 21.7 0.1 01217 8.1 27.1 22.1 13.1 01218 15.3 30.0 22.1 0.0 01219 19.0 32.7 23.1 0.0 01220 25.3 33.1 21.8 0.0 01221 25.9 33.1 21.6 0.3 01222 22.8 32.1 23.3 0.0 01223 14.6 30.7 21.8 9.8 01224 26.5 32.4 21.9 0.0 01225 23.2 32.5 21.9 0.0 01226 17.7 30.5 21.5 2.8 01227 21.1 33.0 23.5 0.1 01228 22.7 33.7 23.0 0.0 01229 18.7 33.8 24.1 1.5 01230 23.1 32.9 23.8 0.0 01231 13.9 30.0 23.4 2.8 01232 25.9 33.9 22.7 0.0 01233 23.8 33.6 21.2 0.0 01234 23.7 33.9 20.1 0.0 01235 20.8 33.4 20.8 0.0 01236 23.8 33.6 19.3 0.0 01237 17.4 34.5 20.8 0.0 01238 23.0 34.3 21.0 0.0 01239 20.9 33.1 21.1 0.0 01240 22.2 33.1 20.8 0.0 01241 23.2 34.5 20.3 0.0

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15101242 20.3 34.7 21.7 0.0 01243 18.3 33.7 21.0 7.5 01244 13.7 30.3 22.4 10.0 01245 17.0 31.4 22.2 4.4 01246 13.1 31.2 21.3 32.0 01247 18.8 31.4 21.2 0.1 01248 21.5 32.8 20.9 0.0 01249 21.0 32.2 22.0 3.3 01250 17.5 31.3 21.6 0.3 01251 20.5 32.3 21.5 0.1 01252 17.7 31.8 21.7 0.0 01253 14.5 31.4 22.3 14.7 01254 13.2 29.9 22.2 3.2 01255 21.3 30.4 21.8 0.1 01256 13.7 28.4 21.7 1.6 01257 3.1 23.5 20.7 10.7 01258 20.6 25.9 19.8 0.0 01259 24.4 28.0 14.7 0.0 01260 21.7 28.7 14.1 0.0 01261 20.3 30.4 16.8 0.0 01262 21.8 30.9 19.5 0.0 01263 16.3 30.9 20.2 0.0 01264 15.6 30.2 20.2 5.3 01265 19.2 31.7 20.7 0.5 01266 17.1 31.3 20.6 5.4 01267 9.1 27.4 21.0 3.7 01268 17.0 25.4 15.5 1.1 01269 15.4 24.1 12.5 0.0 01270 17.5 27.7 13.7 0.0 01271 21.0 27.9 15.3 0.1 01272 19.4 24.0 15.2 0.0 01273 22.2 23.8 11.5 0.0 01274 22.3 23.7 7.0 0.0 01275 22.4 27.4 6.4 0.0 01276 21.9 28.3 7.1 0.0 01277 20.4 29.3 12.0 0.0 01278 15.2 29.4 17.6 0.0 01279 14.4 29.6 19.9 0.0 01280 12.1 22.8 16.2 0.0 01281 14.4 25.2 14.7 0.0 01282 17.6 27.4 14.9 0.0 01283 13.9 27.3 15.9 0.0 01284 17.0 29.9 18.8 0.0 01285 13.1 27.7 18.4 0.0 01286 15.7 29.7 19.4 0.0 01287 8.9 28.5 17.9 0.0 01288 20.0 27.9 14.2 0.1 01289 17.1 26.8 12.9 0.0 01290 19.9 19.5 6.9 0.0 01291 19.2 24.3 3.1 0.0 01292 14.6 27.6 13.5 0.0 01293 17.9 29.6 16.3 0.0 01294 16.3 30.1 15.8 0.0 01295 14.6 30.0 18.5 0.0 01296 13.4 30.3 19.0 0.1 01297 10.6 29.1 18.5 1.3 01298 17.0 30.8 18.1 3.9

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15201299 18.9 23.7 7.2 0.0 01300 17.5 17.9 3.7 0.0 01301 19.1 17.1 1.9 0.0 01302 17.4 22.1 6.2 0.0 01303 18.1 23.9 4.5 0.0 01304 11.9 26.4 9.7 0.0 01305 16.4 29.0 15.1 0.0 01306 13.6 28.6 16.5 0.0 01307 14.1 28.8 18.2 0.0 01308 12.4 27.3 17.3 0.0 01309 10.1 21.2 8.0 0.0 01310 17.5 22.4 3.7 0.0 01311 17.3 24.1 0.0 0.0 01312 16.5 25.2 3.0 0.0 01313 16.1 25.9 6.2 0.0 01314 15.6 25.6 4.4 0.0 01315 15.0 25.8 6.3 0.0 01316 15.1 25.4 7.2 0.0 01317 6.5 21.8 12.1 0.0 01318 6.5 19.6 13.2 6.4 01319 11.7 22.8 14.6 0.0 01320 14.9 24.8 11.5 0.0 01321 15.2 25.9 7.3 0.0 01322 13.9 26.2 10.0 0.0 01323 14.4 26.2 10.2 0.0 01324 11.4 24.4 9.8 0.0 01325 14.5 22.9 8.3 0.0 01326 9.5 23.2 9.1 0.1 01327 4.6 23.2 15.9 11.4 01328 11.9 25.8 14.0 0.1 01329 8.4 26.0 16.5 0.7 01330 13.8 28.1 16.3 0.0 01331 13.3 27.1 14.9 0.0 01332 13.7 26.8 12.9 0.0 01333 12.2 26.5 14.6 0.1 01334 8.4 26.2 16.1 0.0 01335 6.0 24.8 17.7 0.1 01336 12.3 25.1 12.9 0.0 01337 9.6 21.8 7.5 0.0 01338 12.8 23.9 11.5 0.1 01339 10.2 26.5 15.0 0.0 01340 10.7 26.5 14.7 0.0 01341 12.6 27.8 13.6 0.0 01342 5.3 25.0 17.0 5.2 01343 4.2 23.1 19.0 0.2 01344 5.0 23.7 17.9 0.7 01345 7.7 24.5 16.7 0.2 01346 7.8 26.1 16.6 0.0 01347 9.0 26.3 17.2 0.0 01348 6.4 25.3 16.0 3.2 01349 8.0 26.8 19.0 0.3 01350 10.1 26.4 15.5 0.0 01351 10.3 26.6 15.8 4.1 01352 13.7 21.0 8.7 0.1 01353 12.9 20.7 4.2 0.0 01354 13.9 17.8 3.5 0.1 01355 13.9 18.9 -2.0 0.0

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15301356 13.7 22.1 -1.3 0.0 01357 6.2 21.8 6.4 11.8 01358 13.4 17.1 6.1 9.1 01359 2.4 7.6 5.6 0.0 01360 14.0 10.9 -1.5 0.0 01361 8.1 12.6 -4.0 0.0 01362 10.7 18.7 -1.8 0.0 01363 11.9 22.2 8.4 0.0 01364 11.4 15.8 2.6 0.1 01365 4.6 9.9 -1.2 0.0 2002 Weather File *WEATHER DATA : SuwanneFarms,FL @ INSI LAT LONG ELEV TAV AMP REFHT WNDHT UFSU 29.000 -82.000 10 21.2 5.8 2.00 3.00 @DATE SRAD TMAX TMIN RAIN 02001 10.5 13.1 -2.5 2.3 02002 0.9 7.5 1.8 15.7 02003 7.7 5.4 0.8 0.1 02004 14.2 10.0 -4.2 0.0 02005 12.3 14.4 -6.9 0.1 02006 11.8 18.1 7.0 5.9 02007 12.2 11.2 1.3 0.0 02008 14.4 10.8 -3.8 0.0 02009 14.0 17.9 -5.7 0.0 02010 14.2 21.9 2.1 0.2 02011 9.2 20.9 5.7 0.1 02012 4.0 18.7 10.2 10.1 02013 13.9 16.4 3.0 8.2 02014 1.3 11.5 6.3 48.8 02015 12.4 17.6 5.2 0.3 02016 14.3 18.8 -0.4 0.1 02017 12.7 20.3 -0.2 0.0 02018 12.6 24.3 2.1 0.0 02019 12.7 25.3 9.0 1.7 02020 11.6 22.0 10.1 1.6 02021 3.6 21.1 15.0 46.7 02022 4.6 17.9 15.2 0.1 02023 11.7 26.1 12.6 0.0 02024 10.2 24.7 15.7 0.0 02025 2.5 20.9 16.0 17.0 02026 3.5 15.6 13.2 0.1 02027 4.2 18.4 13.4 0.8 02028 10.4 26.4 15.4 11.4 02029 12.1 26.9 17.7 0.1 02030 10.2 27.0 18.5 0.0 02031 14.1 27.9 18.1 0.0 02032 15.4 27.8 14.6 0.0 02033 14.3 20.6 10.0 0.0 02034 13.5 20.7 4.7 0.0 02035 15.2 15.6 4.5 0.0 02036 6.9 10.6 3.0 0.0 02037 7.5 22.4 6.7 0.7 02038 4.6 19.5 3.9 7.1

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15402039 16.1 17.6 0.4 0.0 02040 14.4 23.0 3.3 0.0 02041 9.6 22.2 13.7 0.0 02042 16.2 18.6 6.5 0.0 02043 15.0 19.4 1.9 0.0 02044 5.0 13.4 3.6 0.5 02045 17.0 19.6 4.9 0.0 02046 13.2 22.4 7.9 0.0 02047 14.0 23.0 10.9 0.0 02048 18.4 20.8 1.8 0.0 02049 18.1 18.0 0.2 0.0 02050 18.6 23.1 1.2 0.0 02051 8.9 23.4 8.1 3.5 02052 12.1 23.9 15.8 0.0 02053 5.9 19.5 12.9 0.0 02054 2.2 15.6 7.7 8.4 02055 17.0 18.8 1.1 0.0 02056 17.0 22.2 2.2 0.0 02057 16.8 23.0 3.2 0.0 02058 18.1 16.0 -1.6 0.0 02059 18.5 11.3 -6.3 0.0 02060 14.0 19.0 -4.4 0.0 02061 2.1 20.5 14.7 69.8 02062 2.3 21.3 11.2 63.8 02063 9.5 10.5 -0.5 0.0 02064 19.6 15.4 -4.3 0.0 02065 18.7 21.7 -0.4 0.0 02066 18.4 23.5 7.6 0.0 02067 16.9 26.9 10.5 0.0 02068 19.2 28.3 15.4 0.0 02069 21.5 23.0 11.8 0.0 02070 20.4 25.5 4.6 0.0 02071 11.9 26.0 13.7 5.7 02072 17.5 23.4 13.2 3.0 02073 21.2 24.5 8.5 0.2 02074 19.1 28.7 10.2 0.0 02075 17.1 30.1 15.1 0.0 02076 17.2 31.3 16.7 0.0 02077 20.1 31.0 17.2 0.0 02078 20.5 30.7 13.1 0.1 02079 18.2 27.6 15.9 0.0 02080 9.1 24.7 16.7 3.7 02081 18.7 18.9 8.6 0.0 02082 21.5 21.2 3.4 0.0 02083 19.8 27.1 6.8 0.0 02084 18.0 29.2 13.8 0.0 02085 17.6 28.5 15.3 0.0 02086 18.0 25.5 13.2 0.0 02087 23.3 27.2 7.7 0.0 02088 20.8 27.1 8.6 0.0 02089 20.4 28.9 13.5 0.1 02090 18.6 28.1 18.3 16.2 02091 20.2 26.4 17.9 0.1 02092 17.8 28.0 15.6 0.0 02093 13.8 26.1 18.0 1.8 02094 17.8 27.5 18.0 0.0 02095 18.6 22.7 10.9 0.0

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15502096 24.4 24.0 8.5 0.0 02097 20.3 24.3 10.6 0.0 02098 20.3 26.2 13.8 0.0 02099 18.9 27.5 17.2 0.0 02100 11.2 25.4 18.3 18.8 02101 7.4 24.7 18.7 20.9 02102 17.0 26.1 17.0 1.1 02103 10.9 23.5 18.3 3.5 02104 19.9 27.0 17.7 0.0 02105 19.4 28.3 14.8 0.1 02106 23.1 30.4 16.4 29.6 02107 22.7 30.1 18.3 0.1 02108 20.0 29.0 18.2 0.0 02109 25.9 31.9 19.1 0.2 02110 23.2 31.7 17.9 0.0 02111 24.5 31.7 17.5 0.0 02112 22.3 31.3 17.9 0.0 02113 22.3 29.4 16.8 0.0 02114 24.8 30.2 14.8 0.0 02115 22.5 29.8 20.9 0.0 02116 22.4 30.0 17.8 0.0 02117 20.4 30.3 17.9 0.0 02118 22.2 28.9 17.8 0.0 02119 17.0 29.8 19.2 0.0 02120 19.4 30.1 18.4 0.0 02121 23.4 29.6 19.5 0.1 02122 22.5 29.9 19.2 0.0 02123 24.2 31.7 20.4 0.1 02124 23.2 33.2 20.2 0.1 02125 19.9 30.7 19.7 0.1 02126 21.3 30.3 18.8 0.0 02127 22.3 31.4 18.6 0.0 02128 23.5 33.5 18.7 0.0 02129 22.3 33.7 19.1 0.0 02130 24.5 34.8 20.1 0.0 02131 25.0 33.6 19.9 0.0 02132 24.9 33.8 19.0 0.0 02133 22.7 31.0 21.2 0.0 02134 26.3 28.1 16.5 2.2 02135 24.7 29.1 9.4 0.0 02136 26.0 32.0 14.4 0.0 02137 21.9 31.7 19.0 0.0 02138 11.3 27.8 20.6 8.1

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APPENDIX D HYDRUS INPUT FILES

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157Flat Surface Input Files BOUNDARY.IN Pcp_File_Version=2 *** BLOCK ?: BOUNDARY INFORMATION ********************************************* NumBP NObs SeepF FreeD DrainF qQWLF 62 0 f t f f Node Number Array 1 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 Width Array 1.5 1.5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1.5 1.5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Length of soil surface associated with transpiration 90 *** BLOCK ?: Solute transport boundary conditions ***************************** KodCB(1),KodCB(2),.....,KodCB(NumBP) -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 *** End of input file 'BOUNDARY.IN' ******************************************* DIMENSIO.IN Pcp_File_Version=2 NumNPD NumElD NumBPD MBandD NSeepD NumSPD NDrD NElDrD NMatD NObsD NSD 206 291 62 15 1 1 1 20 4 1 3

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158158ATMOSPH.IN Pcp_File_Version=2 *** BLOCK I: ATMOSPHERIC INFORMATION ********************************** MaxAL (MaxAL = number of atmospheric data-records) 130 hCritS (max. allowed pressure head at the soil surface) 0 tAtm Prec rSoil rRoot hCritA rt ht cValue1 cValue2 cValue3 1 0 0.249 0 10000 0 0 0 0 0 0 0 0 0 0 0 2 0.001 0.289 0 10000 0 0 180.399 0 0 0 0 0 639.58 0 0 3 0 0.191 0 10000 0 0 0 0 0 0 0 0 0 0 0 4 1.1 0.084 0 10000 0 0 0 0 0 0 0 0 0 0 0 5 0.8 0.264 0 10000 0 0 0 0 0 0 0 0 0 0 0 6 4.9 0.024 0 10000 0 0 0 0 0 0 0 0 0 0 0 7 0.001 0.245 0 10000 0 0 62.7 0 0 0 0 0 222.3 0 0 8 0 0.272 0 10000 0 0 0 0 0 0 0 0 0 0 0 9 0 0.248 0 10000 0 0 0 0 0 0 0 0 0 0 0 10 0 0.265 0 10000 0 0 0 0 0 0 0 0 0 0 0 11 0.2 0.288 0 10000 0 0 0 0 0 0 0 0 0 0 0 12 0.1 0.254 0 10000 0 0 0 0 0 0 0 0 0 0 0 13 4.7 0.081 0 10000 0 0 0 0 0 0 0 0 0 0 0 14 0 0.1 0 10000 0 0 0 0 0 0 0 0 0 0 0 15 0 0.276 0 10000 0 0 0 0 0 0 0 0 0 0 0 16 0 0.242 0 10000 0 0 0 0 0 0 0 0 0 0 0 17 1.7 0.057 0 10000 0 0 0 0 0 0 0 0 0 0 0 18 0 0.072 0 10000 0 0 0 0 0 0 0 0 0 0 0

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159159 19 0.1 0.09 0 10000 0 0 0 0 0 0 0 0 0 0 0 20 1.1 0.252 0 10000 0 0 0 0 0 0 0 0 0 0 0 21 0 0.3 0 10000 0 0 0 0 0 0 0 0 0 0 0 22 0 0.254 0 10000 0 0 0 0 0 0 0 0 0 0 0 23 0 0.354 0 10000 0 0 0 0 0 0 0 0 0 0 0 24 0 0.376 0 10000 0 0 0 0 0 0 0 0 0 0 0 25 0 0.308 0 10000 0 0 0 0 0 0 0 0 0 0 0 26 0 0.277 0 10000 0 0 0 0 0 0 0 0 0 0 0 27 0 0.289 0 10000 0 0 0 0 0 0 0 0 0 0 0 28 0 0.12 0 10000 0 0 0 0 0 0 0 0 0 0 0 29 0.1 0.16 0 10000 0 0 0 0 0 0 0 0 0 0 0 30 0.7 0.092 0 10000 0 0 0 0 0 0 0 0 0 0 0 31 0 0.303 0 10000 0 0 0 0 0 0 0 0 0 0 0 32 0 0.301 0 10000 0 0 0 0 0 0 0 0 0 0 0 33 0 0.218 0 10000 0 0 0 0 0 0 0 0 0 0 0 34 0 0.329 0 10000 0 0 0 0 0 0 0 0 0 0 0 35 0 0.294 0 10000 0 0 0 0 0 0 0 0 0 0 0 36 0.1 0.091 0 10000 0 0 0.374 0 0 0 0 0 1.326 0 0 37 0 0.344 0 10000 0 0 0 0 0 0 0 0 0 0 0 38 0 0.285 0 10000 0 0 0 0 0 0 0 0 0 0 0 39 0 0.313 0 10000 0 0 0 0 0 0 0 0 0 0 0 40 0 0.368 0 10000 0 0 0 0 0 0 0 0 0 0 0 41 0 0.342 0 10000 0 0 0 0 0 0 0 0 0 0 0

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160160 42 0 0.382 0 10000 0 0 0 0 0 0 0 0 0 0 0 43 0.3 0.195 0 10000 0 0 0 0 0 0 0 0 0 0 0 44 0 0.285 0 10000 0 0 0 0 0 0 0 0 0 0 0 45 0 0.128 0 10000 0 0 0 0 0 0 0 0 0 0 0 46 0.9 0.043 0 10000 0 0 0 0 0 0 0 0 0 0 0 47 0 0.328 0 10000 0 0 0 0 0 0 0 0 0 0 0 48 0 0.348 0 10000 0 0 0 0 0 0 0 0 0 0 0 49 0 0.351 0 10000 0 0 0 0 0 0 0 0 0 0 0 50 0 0.326 0 10000 0 0 0 0 0 0 0 0 0 0 0 51 0.6 0.292 0 10000 0 0 0 0 0 0 0 0 0 0 0 52 0 0.257 0 10000 0 0 0 0 0 0 0 0 0 0 0 53 6.9 0.047 0 10000 0 0 0 0 0 0 0 0 0 0 0 54 6.4 0.05 0 10000 0 0 0 0 0 0 0 0 0 0 0 55 0 0.158 0 10000 0 0 0 0 0 0 0 0 0 0 0 56 0 0.339 0 10000 0 0 0 0 0 0 0 0 0 0 0 57 0 0.371 0 10000 0 0 0 0 0 0 0 0 0 0 0 58 0 0.403 0 10000 0 0 0 0 0 0 0 0 0 0 0 59 0 0.395 0 10000 0 0 0 0 0 0 0 0 0 0 0 60 0 0.475 0 10000 0 0 0 0 0 0 0 0 0 0 0 61 0 0.482915 0.0020855 10000 0 0 0 0 0 0 0 0 0 0 0 62 0 0.444082 0.0019178 10000 0 0 0 0 0 0 0 0 0 0 0 63 0.6 0.280787 0.0012126 10000 0 0 0 0 0 0 0 0 0 0 0 64 0.3 0.397551 0.0034486 10000 0 0 0 1599.27 0 0 0 0 0.744335 0 0

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161161 65 0.8 0.466898 0.0061017 10000 0 0 0 0 0 0 0 0 0 0 0 66 0 0.444239 0.009761 10000 0 0 0 0 0 0 0 0 0 0 0 67 0.7 0.416087 0.0129129 10000 0 0 0 0 0 0 0 0 0 0 0 68 0 0.424895 0.0171054 10000 0 0 0 0 0 0 0 0 0 0 0 69 0 0.491593 0.0244068 10000 0 0 0 0 0 0 0 0 0 0 0 70 0.9 0.479603 0.0283972 10000 0 0 0 0 0 0 0 0 0 0 0 71 0 0.413453 0.0305472 10000 0 0 0 0 0 0 0 0 0 0 0 72 0.4 0.199283 0.0157165 10000 0 0 0 0 0 0 0 0 0 0 0 73 0 0.350062 0.032938 10000 0 0 0 0 0 0 0 0 0 0 0 74 0.9 0.388314 0.0446856 10000 0 0 0 0 0 0 0 0 0 0 0 75 0.9 0.389663 0.0533372 10000 0 0 0 0 0 0 0 0 0 0 0 76 0.5 0.374132 0.0618684 10000 0 0 8.36816 0 0 0 0 0 29.6689 0 0 77 0.9 0.35456 0.0714402 10000 0 0 0 0 0 0 0 0 0 0 0 78 0.9 0.332278 0.079722 10000 0 0 0 0 0 0 0 0 0 0 0 79 0.9 0.396257 0.122744 10000 0 0 0 0 0 0 0 0 0 0 0 80 0.9 0.334312 0.129688 10000 0 0 0 0 0 0 0 0 0 0 0 81 0.9 0.323809 0.157191 10000 0 0 0 0 0 0 0 0 0 0 0 82 2.5 0.278477 0.169523 10000 0 0 0 0 0 0 0 0 0 0 0 83 0.9 0.284262 0.189738 10000 0 0 0 0 0 0 0 0 0 0 0 84 0 0.232518 0.182482 10000 0 0 0 0 0 0 0 0 0 0 0 85 0.2 0.172411 0.146589 10000 0 0 0 0 0 0 0 0 0 0 0 86 1 0.215676 0.201324 10000 0 0 0 0 0 0 0 0 0 0 0 87 0.9 0.193082 0.193918 10000 0 0 0 0 0 0 0 0 0 0 0

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162162 88 0.9 0.237761 0.266239 10000 0 0 0 0 0 0 0 0 0 0 0 89 0.9 0.191996 0.235004 10000 0 0 0 0 0 0 0 0 0 0 0 90 0.9 0.194315 0.253685 10000 0 0 0 0 0 0 0 0 0 0 0 91 0.9 0.182315 0.251685 10000 0 0 0 0 0 0 0 0 0 0 0 92 1.9 0.104176 0.148824 10000 0 0 0 0 0 0 0 0 0 0 0 93 2.1 0.0683525 0.0976475 10000 0 0 0 0 0 0 0 0 0 0 0 94 0.1 0.157923 0.224077 10000 0 0 0 0 0 0 0 0 0 0 0 95 0.3 0.0996166 0.140383 10000 0 0 0 0 0 0 0 0 0 0 0 96 0 0.189613 0.265387 10000 0 0 0 0 0 0 0 0 0 0 0 97 1 0.184097 0.255903 10000 0 0 0 0 0 0 0 0 0 0 0 98 3.6 0.228103 0.314897 10000 0 0 0 0 0 0 0 0 0 0 0 99 0.9 0.227752 0.312248 10000 0 0 0 0 0 0 0 0 0 0 0 100 0.5 0.199023 0.270977 10000 0 0 0 0 0 0 0 0 0 0 0 101 0.7 0.268696 0.363304 10000 0 0 0 0 0 0 0 0 0 0 0 102 0.7 0.239997 0.320003 10000 0 0 0 0 0 0 0 0 0 0 0 103 0.7 0.253867 0.336133 10000 0 0 0 0 0 0 0 0 0 0 0 104 0.7 0.231989 0.305011 10000 0 0 0 0 0 0 0 0 0 0 0 105 0.9 0.226884 0.294116 10000 0 0 0 0 0 0 0 0 0 0 0 106 0.9 0.251841 0.324159 10000 0 0 0 0 0 0 0 0 0 0 0 107 0.9 0.240201 0.304799 10000 0 0 0 0 0 0 0 0 0 0 0 108 0.8 0.236355 0.295645 10000 0 0 0 0 0 0 0 0 0 0 0 109 0.8 0.217652 0.268348 10000 0 0 0 0 0 0 0 0 0 0 0 110 0.8 0.235201 0.285799 10000 0 0 0 0 0 0 0 0 0 0 0

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163163 111 0.8 0.185212 0.221788 10000 0 0 0 0 0 0 0 0 0 0 0 112 0.8 0.2137 0.2503 10000 0 0 0 0 0 0 0 0 0 0 0 113 0.9 0.26045 0.30055 10000 0 0 0 0 0 0 0 0 0 0 0 114 0.8 0.253727 0.286273 10000 0 0 0 0 0 0 0 0 0 0 0 115 0.7 0.283236 0.314764 10000 0 0 0 0 0 0 0 0 0 0 0 116 0 0.278986 0.303014 10000 0 0 0 0 0 0 0 0 0 0 0 117 0 0.235295 0.249705 10000 0 0 0 0 0 0 0 0 0 0 0 118 0.6 0.252374 0.261626 10000 0 0 0 0 0 0 0 0 0 0 0 119 0.6 0.270329 0.273671 10000 0 0 0 0 0 0 0 0 0 0 0 120 0 0.295218 0.291782 10000 0 0 0 0 0 0 0 0 0 0 0 121 0.4 0.286182 0.273818 10000 0 0 0 0 0 0 0 0 0 0 0 122 0.4 0.324807 0.303193 10000 0 0 0 0 0 0 0 0 0 0 0 123 0.4 0.332148 0.299852 10000 0 0 0 0 0 0 0 0 0 0 0 124 0 0.33403 0.29397 10000 0 0 0 0 0 0 0 0 0 0 0 125 0 0.306591 0.258409 10000 0 0 0 0 0 0 0 0 0 0 0 126 0.2 0.338003 0.274997 10000 0 0 0 0 0 0 0 0 0 0 0 127 0 0.310517 0.241483 10000 0 0 0 0 0 0 0 0 0 0 0 128 0 0.358684 0.266316 10000 0 0 0 0 0 0 0 0 0 0 0 129 0 0.318505 0.225495 10000 0 0 0 0 0 0 0 0 0 0 0 130 0.8 0.159253 0.112747 10000 0 0 0 0 0 0 0 0 0 0 0 *** END OF INPUT FILE 'ATMOSPH.IN' *************************************

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164164SELECTOR.IN Pcp_File_Version=2 *** BLOCK A: BASIC INFORMATION ***************************************** Heading Welcome to HYDRUS-2D LUnit TUnit MUnit (indicated units are obligatory for all input data) cm days -mg Kat (0:horizontal plane, 1:axisymmetric vertical flow, 2:vertical plane) 2 MaxIt TolTh TolH InitH/W (max. number of iterations and tolerances) 10000 0.0001 0.1 t lWat lChem lSink Short Flux lScrn AtmIn lTemp lWTDep lEquil lExtGen lInv t t t f t t t f f t t f *** BLOCK B: MATERIAL INFORMATION ************************************** NMat NLay hTab1 hTabN 4 5 1e-006 10000 Model Hysteresis 2 0 thr ths Alfa n Ks l 0.03 0.3883 0.061 0.753 4515 2 0.03 0.3883 0.061 0.753 4515 2 0.03 0.3526 0.053 0.754 3759 2 0.03 0.3526 0.053 0.754 3759 2 *** BLOCK C: TIME INFORMATION ****************************************** dt dtMin dtMax DMul DMul2 ItMin ItMax MPL 0.0001 1e-005 0.0001 1.5 0.1 3 7 100 tInit tMax 0 130 TPrint(1),TPrint(2),...,TPrint(MPL) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 71 73 75 77 79 81 82 84 86 88 90 92 94 96 98

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165165 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 *** BLOCK G: SOLUTE TRANSPORT INFORMATION ***************************************************** Epsi lUpW lArtD lTDep cTolA cTolR MaxItC PeCr Nu.of Solutes Tortuosity 1 f f f 0 0 1 1 3 t Bulk.d. DisperL. DisperT Frac ThImob (1..NMat) 1.48 10 10 1 0 1.48 10 10 1 0 1.56 10 10 1 0 1.56 10 10 1 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

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166166 cTop cBot 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 tPulse 1 *** BLOCK G: ROOT WATER UPTAKE INFORMATION ***************************** Model (0 Feddes, 1 S shape) 0 P0 P2H P2L P3 r2H r2L -10 -320 -600 -6000 0.5 0.1 POptm(1),POptm(2),...,POptm(NMat) -25 -25 -25 -25 Solute Reduction f *** END OF INPUT FILE 'SELECTOR.IN' ************************************

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167 167MESHTRIA.000 1 206 496 291 119 1 0 90 30 0 2 0 86.8966 62.0689 0 3 -5.42101e-020 83.7931 62.0689 0 4 0 80.6897 62.0689 0 5 6.77626e-020 77.5862 62.0689 0 6 1.35525e-020 74.4828 62.0689 0 7 0 71.3793 62.0689 0 8 -5.42101e-020 68.2759 62.0689 0 9 -4.06576e-020 65.1724 62.0689 0 10 0 62.069 62.0689 0 11 1.35525e-020 58.9655 62.0689 0 12 5.42101e-020 55.8621 62.0689 0 13 0 52.7586 62.0689 0 14 0 49.6552 62.0689 0 15 -2.71051e-020 46.5517 62.0689 0 16 0 43.4483 62.0689 0 17 0 40.3448 62.0689 0 18 6.77626e-021 37.2414 62.0689 0 19 -2.71051e-020 34.1379 62.0689 0 20 -2.71051e-020 31.0345 62.0689 0 21 2.71051e-020 27.931 62.0689 0 22 0 24.8276 62.0689 0 23 0 21.7241 62.0689 0 24 3.38813e-021 18.6207 62.0689 0 25 -1.35525e-020 15.5172 62.0689 0 26 1.35525e-020 12.4138 62.0689 0 27 0 9.31035 62.0689 0 28 0 6.20689 62.0689 0 29 0 3.10345 62.0689 0 30 0 0 30 0 31 3 0 30 0 32 6 0 30 0 33 9 6.77626e-021 30 0 34 12 0 30 0 35 15 0 30 0 36 18 1.35525e-020 30 0 37 21 0 30 0 38 24 0 30 0 39 27 0 30 0 40 30 0 30 0 41 33 0 30 0 42 36 2.71051e-020 30 0 43 39 2.71051e-020 30 0 44 42 0 30 0 45 45 0 30 0 46 48 0 30 0 47 51 0 30 0 48 54 0 30 0 49 57 0 30 0 50 60 0 30 0 51 63 -5.42101e-020 30 0 52 66 0 30 0 53 69 1.35525e-020 30 0 54 72 5.42101e-020 30 0 55 75 -2.71051e-020 30 0 56 78 5.42101e-020 30 0 57 81 -5.42101e-020 30 0 58 84 0 30 0 59 87 2.71051e-020 30 0

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168 168 60 90 0 30 0 61 90 3 60 0 62 90 6 60 0 63 90 9 60 0 64 90 12 60 0 65 90 15 60 0 66 90 18 60 0 67 90 21 60 0 68 90 24 60 0 69 90 27 60 0 70 90 30 60 0 71 90 33 60 0 72 90 36 60 0 73 90 39 60 0 74 90 42 60 0 75 90 45 60 0 76 90 48 60 0 77 90 51 60 0 78 90 54 60 0 79 90 57 60 0 80 90 60 60 0 81 90 63 60 0 82 90 66 60 0 83 90 69 60 0 84 90 72 60 0 85 90 75 60 0 86 90 78 60 0 87 90 81 60 0 88 90 84 60 0 89 90 87 60 0 90 90 90 30 0 91 87 90 30 0 92 84 90 30 0 93 81 90 30 0 94 78 90 30 0 95 75 90 30 0 96 72 90 30 0 97 69 90 30 0 98 66 90 30 0 99 63 90 30 0 100 60 90 30 0 101 57 90 30 0 102 54 90 30 0 103 51 90 30 0 104 48 90 30 0 105 45 90 30 0 106 42 90 30 0 107 39 90 30 0 108 36 90 30 0 109 33 90 30 0 110 30 90 30 0 111 27 90 30 0 112 24 90 30 0 113 21 90 30 0 114 18 90 30 0 115 15 90 30 0 116 12 90 30 0 117 9 90 30 0 118 6 90 30 0 119 3 90 30 0 120 19.6023 2.4352 34.5698 3 121 61.504 29.8855 55.8617 3 122 17.8085 84.5616 41.4527 3

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169 169 123 9.31046 84.1171 47.9388 3 124 18.6723 87.7966 34.6496 3 125 12.8735 87.4338 37.1685 3 126 6.45799 87.4213 41.7075 3 127 31.0928 77.435 46.1627 3 128 15.9971 75.7699 52.9871 3 129 31.2685 84.8878 37.194 3 130 23.4747 81.4342 43.8452 3 131 12.5761 80.487 50.8184 3 132 24.817 86.6928 35.6062 3 133 47.0699 85.3761 35.9595 3 134 46.4369 62.2768 54.8006 3 135 22.3873 49.877 59.1618 3 136 43.9465 45.6835 57.8736 3 137 66.6426 42.487 58.3839 3 138 22.2219 41.3299 59.0292 3 139 72.4726 36.622 58.1575 3 140 53.6113 36.7507 56.8694 3 141 77.4469 30.8665 58.0712 3 142 28.3932 31.1514 56.3697 3 143 66.8181 48.0205 58.4574 3 144 62.159 60.4229 56.2442 3 145 18.7788 60.0928 58.3269 3 146 77.7217 59.2923 58.2433 3 147 53.4906 53.8707 57.1534 3 148 72.6366 53.6268 58.316 3 149 38.4292 84.3412 37.2587 3 150 43.5254 78.8509 43.4841 3 151 20.6905 69.4094 54.8885 3 152 53.7767 74.3898 48.4903 3 153 39.8226 70.9387 50.6657 3 154 70.4703 71.6944 53.6925 3 155 56.4555 67.8254 53.1245 3 156 73.3956 65.5922 56.576 3 157 63.1448 77.2574 47.6313 3 158 76.1142 87.7074 36.3382 3 159 69.5756 87.9004 34.4381 3 160 71.1932 84.8739 40.8071 3 161 63.6964 86.7124 35.668 3 162 76.9566 81.1523 49.3902 3 163 64.8526 82.0051 42.9959 3 164 56.1755 86.0394 35.7529 3 165 75.6152 76.8334 52.2168 3 166 53.8917 80.9768 41.8954 3 167 80.2319 84.4647 46.6968 3 168 83.1972 87.5163 41.0019 3 169 63.9115 3.26802 35.5478 3 170 76.1897 2.2795 36.2828 3 171 83.2324 2.47698 40.976 3 172 71.4123 5.09773 40.6698 3 173 80.3323 5.52051 46.6266 3 174 69.682 2.08662 34.3738 3 175 39.2805 5.78846 36.8969 3 176 56.5333 3.92792 35.5474 3 177 65.3348 7.94742 42.7252 3 178 77.1729 8.83136 49.2565 3 179 54.8522 8.94932 41.4099 3 180 75.9299 13.1672 52.0053 3 181 47.6436 4.58054 35.6202 3 182 64.0501 12.7011 47.2222 3 183 45.2849 11.0588 42.6515 3 184 55.6635 15.5302 47.7866 3 185 44.057 18.7564 49.1872 3

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170 170 186 71.0689 18.433 53.4133 3 187 57.4033 22.5377 52.6454 3 188 73.578 24.6401 56.3618 3 189 44.6307 27.9828 54.2072 3 190 31.3211 22.0121 52.3142 3 191 18.3033 6.48598 42.0993 3 192 25.476 4.08738 36.2458 3 193 12.7933 11.5263 51.8679 3 194 24.3497 10.0745 44.4574 3 195 31.9938 5.54705 37.1441 3 196 18.3619 17.3646 53.1779 3 197 33.5738 13.1424 45.3581 3 198 9.88802 6.64835 48.1199 3 199 6.83532 2.8042 41.6671 3 200 13.4246 2.94038 37.281 3 201 38.4127 36.8519 56.9325 3 202 10.8776 54.4743 60.325 3 203 36.1532 55.2619 57.2056 3 204 32.4176 63.8646 55.055 3 205 13.7413 34.22 59.327 3 206 15.8189 25.7206 57.2955 3 1 1 2 119 0 12 0 1 2 2 3 126 0 131 0 1 3 3 4 123 0 130 0 1 4 4 5 131 0 124 0 1 5 5 6 128 0 22 0 1 6 6 7 128 0 134 0 1 7 7 8 151 0 42 0 1 8 8 9 151 0 44 0 1 9 9 10 145 0 25 0 1 10 10 11 145 0 36 0 1 11 11 12 202 0 282 0 1 12 12 13 202 0 168 0 1 13 13 14 202 0 172 0 1 14 14 15 135 0 148 0 1 15 15 16 138 0 29 0 1 16 16 17 138 0 154 0 1 17 17 18 205 0 162 0 1 18 18 19 205 0 288 0 1 19 19 20 205 0 256 0 1 20 20 21 206 0 248 0 1 21 21 22 206 0 258 0 1 22 22 23 206 0 98 0 1 23 23 24 196 0 264 0 1 24 24 25 196 0 104 0 1 25 25 26 193 0 274 0 1 26 26 27 193 0 276 0 1 27 27 28 198 0 111 0 1 28 28 29 199 0 107 0 1 29 29 30 31 0 110 0 1 30 30 31 29 0 110 0 1 31 31 32 199 0 108 0 1 32 32 33 199 0 113 0 1 33 33 34 200 0 112 0 1 34 34 35 200 0 115 0 1 35 35 36 120 0 117 0 1 36 36 37 120 0 278 0 1 37 37 38 120 0 99 0 1 38 38 39 192 0 260 0 1 39 39 40 192 0 262 0 1 40 40 41 195 0 103 0 1 41 41 42 195 0 268 0 1

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171 171 42 42 43 175 0 272 0 1 43 43 44 175 0 83 0 1 44 44 45 181 0 228 0 1 45 45 46 181 0 240 0 1 46 46 47 181 0 236 0 1 47 47 48 176 0 230 0 1 48 48 49 176 0 216 0 1 49 49 50 176 0 84 0 1 50 50 51 169 0 68 0 1 51 51 52 169 0 226 0 1 52 52 53 174 0 82 0 1 53 53 54 174 0 79 0 1 54 54 55 170 0 69 0 1 55 55 56 170 0 71 0 1 56 56 57 170 0 72 0 1 57 57 58 171 0 74 0 1 58 58 59 171 0 75 0 1 59 59 60 61 0 76 0 1 60 60 61 59 0 76 0 1 61 61 62 171 0 221 0 1 62 62 63 173 0 220 0 1 63 63 64 178 0 224 0 1 64 64 65 180 0 234 0 1 65 65 66 180 0 238 0 1 66 66 67 186 0 246 0 1 67 67 68 188 0 250 0 1 68 68 69 188 0 94 0 1 69 69 70 141 0 2 0 1 70 70 71 141 0 120 0 1 71 71 72 141 0 32 0 1 72 72 73 139 0 30 0 1 73 73 74 139 0 156 0 1 74 74 75 137 0 152 0 1 75 75 76 143 0 164 0 1 76 76 77 148 0 174 0 1 77 77 78 148 0 170 0 1 78 78 79 146 0 166 0 1 79 79 80 146 0 190 0 1 80 80 81 146 0 186 0 1 81 81 82 156 0 45 0 1 82 82 83 156 0 48 0 1 83 83 84 154 0 208 0 1 84 84 85 165 0 57 0 1 85 85 86 165 0 212 0 1 86 86 87 162 0 214 0 1 87 87 88 167 0 66 0 1 88 88 89 168 0 63 0 1 89 89 90 91 0 67 0 1 90 90 91 89 0 67 0 1 91 91 92 168 0 62 0 1 92 92 93 168 0 64 0 1 93 93 94 158 0 49 0 1 94 94 95 158 0 60 0 1 95 95 96 158 0 50 0 1 96 96 97 159 0 194 0 1 97 97 98 159 0 52 0 1 98 98 99 161 0 198 0 1 99 99 100 161 0 200 0 1 100 100 101 164 0 56 0 1 101 101 102 164 0 206 0 1 102 102 103 164 0 204 0 1 103 103 104 133 0 24 0 1 104 104 105 133 0 144 0 1

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172 172 105 105 106 133 0 40 0 1 106 106 107 149 0 132 0 1 107 107 108 149 0 136 0 1 108 108 109 129 0 142 0 1 109 109 110 129 0 20 0 1 110 110 111 132 0 23 0 1 111 111 112 132 0 126 0 1 112 112 113 132 0 128 0 1 113 113 114 124 0 5 0 1 114 114 115 124 0 6 0 1 115 115 116 125 0 7 0 1 116 116 117 125 0 8 0 1 117 117 118 126 0 10 0 1 118 118 119 126 0 11 0 1 119 119 1 2 0 12 0 1 120 191 200 120 198 275 119 0 121 200 120 191 35 275 277 0 122 140 189 121 201 163 31 0 123 189 121 140 187 163 255 0 124 168 91 92 89 62 3 0 125 91 89 90 168 67 3 0 126 123 122 125 131 125 141 0 127 132 122 130 124 123 4 0 128 117 125 116 126 8 13 0 129 115 125 124 116 16 7 0 130 3 126 2 123 131 17 0 131 117 126 125 118 13 10 0 132 125 116 117 115 8 7 0 133 2 126 119 3 9 131 0 134 118 126 117 119 10 11 0 135 119 126 118 2 11 9 0 136 2 119 1 126 12 9 0 137 122 125 123 124 125 127 0 138 125 124 115 122 16 127 0 139 126 125 117 123 13 129 0 140 128 127 130 151 135 178 0 141 149 127 150 129 133 18 0 142 127 130 128 129 135 137 0 143 130 129 132 127 21 137 0 144 131 130 122 128 143 139 0 145 131 122 123 130 141 143 0 146 150 166 133 152 193 179 0 147 166 133 150 164 193 58 0 148 144 134 147 155 167 147 0 149 144 155 134 156 147 191 0 150 136 147 203 143 38 149 0 151 143 147 136 148 149 175 0 152 137 136 140 143 153 151 0 153 143 136 137 147 151 149 0 154 136 140 137 201 153 157 0 155 140 137 136 139 153 155 0 156 140 139 137 121 155 161 0 157 121 139 140 141 161 159 0 158 140 121 139 189 161 163 0 159 134 147 144 203 167 171 0 160 147 144 134 148 167 173 0 161 144 148 146 147 169 173 0 162 148 147 143 144 175 173 0 163 150 149 127 133 133 41 0 164 127 153 150 151 177 183 0 165 152 166 150 157 179 145 0 166 153 150 127 152 177 181 0 167 153 152 150 155 181 187 0

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173 173 168 155 152 153 154 187 185 0 169 155 154 152 156 185 189 0 170 156 155 144 154 191 189 0 171 93 158 168 94 65 49 0 172 88 168 167 89 61 63 0 173 159 158 96 160 215 213 0 174 168 158 167 93 195 65 0 175 160 158 159 167 213 197 0 176 161 160 159 163 51 203 0 177 167 160 162 158 199 197 0 178 160 162 167 163 199 201 0 179 163 162 160 165 201 205 0 180 164 163 161 166 55 209 0 181 163 165 162 157 205 207 0 182 163 157 165 166 207 211 0 183 158 95 96 94 50 60 0 184 168 92 93 91 64 62 0 185 168 89 91 88 3 63 0 186 168 93 158 92 65 64 0 187 158 94 95 93 60 49 0 188 172 169 174 177 80 217 0 189 172 177 169 178 217 235 0 190 171 170 57 173 77 227 0 191 174 170 172 54 219 70 0 192 62 171 61 173 221 78 0 193 170 57 171 56 77 72 0 194 57 171 170 58 77 74 0 195 170 56 57 55 72 71 0 196 61 171 59 62 73 221 0 197 58 171 57 59 74 75 0 198 59 171 58 61 75 73 0 199 61 59 60 171 76 73 0 200 170 55 56 54 71 69 0 201 173 172 170 178 225 223 0 202 172 170 173 174 225 219 0 203 183 175 181 197 244 91 0 204 197 175 183 195 91 105 0 205 177 176 169 179 85 231 0 206 177 179 176 182 231 239 0 207 178 177 172 180 235 233 0 208 177 182 179 180 239 241 0 209 181 179 183 176 237 87 0 210 179 183 181 184 237 243 0 211 184 179 182 183 245 243 0 212 185 197 183 190 259 273 0 213 185 184 187 183 249 247 0 214 185 183 184 197 247 259 0 215 184 187 185 186 249 251 0 216 187 186 188 184 253 251 0 217 188 187 186 121 253 257 0 218 121 187 188 189 257 255 0 219 192 191 120 194 1 265 0 220 198 191 193 200 261 119 0 221 191 193 198 194 261 263 0 222 194 193 191 196 263 267 0 223 195 194 192 197 102 271 0 224 194 196 193 197 267 269 0 225 197 196 194 190 269 229 0 226 32 199 31 33 108 113 0 227 199 29 31 28 109 107 0 228 31 199 29 32 109 108 0 229 31 29 30 199 110 109 0 230 34 200 33 35 112 115 0

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174 174 231 199 28 29 198 107 114 0 232 33 200 199 34 116 112 0 233 35 200 34 120 115 277 0 234 200 199 33 198 116 279 0 235 199 33 200 32 116 113 0 236 120 38 192 37 118 99 0 237 198 200 191 199 119 279 0 238 120 192 191 38 1 118 0 239 71 141 70 72 120 32 0 240 142 189 201 190 121 97 0 241 70 141 69 71 2 120 0 242 132 112 113 111 128 126 0 243 122 130 132 131 123 143 0 244 132 111 112 110 126 23 0 245 5 131 4 128 124 140 0 246 122 124 125 132 127 4 0 247 4 131 123 5 14 124 0 248 124 132 113 122 15 4 0 249 125 123 122 126 125 129 0 250 113 132 112 124 128 15 0 251 124 114 115 113 6 5 0 252 126 123 125 3 129 17 0 253 124 113 114 132 5 15 0 254 4 123 3 131 130 14 0 255 115 124 114 125 6 16 0 256 3 123 126 4 17 130 0 257 149 108 129 107 138 136 0 258 127 150 149 153 133 177 0 259 149 107 108 106 136 132 0 260 7 151 128 8 19 42 0 261 127 129 130 149 137 18 0 262 128 7 151 6 19 134 0 263 129 149 108 127 138 18 0 264 130 128 127 131 135 139 0 265 108 129 149 109 138 142 0 266 129 110 132 109 122 20 0 267 131 128 130 5 139 140 0 268 109 129 108 110 142 20 0 269 6 128 5 7 22 134 0 270 130 132 122 129 123 21 0 271 128 5 6 131 22 140 0 272 132 129 110 130 122 21 0 273 123 131 122 4 141 14 0 274 110 132 129 111 122 23 0 275 105 133 104 106 144 40 0 276 157 166 152 163 145 211 0 277 104 133 103 105 24 144 0 278 145 11 202 10 146 36 0 279 144 156 155 146 191 35 0 280 10 145 9 11 25 36 0 281 15 135 14 138 148 150 0 282 143 148 147 76 175 39 0 283 14 135 202 15 26 148 0 284 15 138 135 16 150 29 0 285 137 143 136 75 151 34 0 286 135 138 136 15 27 150 0 287 75 137 74 143 152 34 0 288 136 138 201 135 280 27 0 289 74 137 139 75 28 152 0 290 17 138 16 205 154 158 0 291 139 137 140 74 155 28 0 292 16 138 15 17 29 154 0 293 74 139 73 137 156 28 0

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175 175 294 136 201 140 138 157 280 0 295 73 139 72 74 30 156 0 296 17 205 138 18 158 162 0 297 141 139 121 72 159 160 0 298 138 142 201 205 281 33 0 299 72 139 141 73 160 30 0 300 189 201 142 140 121 31 0 301 72 141 71 139 32 160 0 302 205 20 206 19 252 256 0 303 121 141 139 188 159 254 0 304 138 205 142 17 33 158 0 305 76 143 75 148 164 39 0 306 135 136 203 138 165 27 0 307 75 143 137 76 34 164 0 308 146 80 81 79 186 190 0 309 203 204 145 134 284 286 0 310 146 79 80 78 190 166 0 311 202 135 145 14 283 26 0 312 146 144 148 156 169 35 0 313 202 13 14 12 172 168 0 314 78 146 148 79 37 166 0 315 134 203 147 204 171 286 0 316 148 78 146 77 37 170 0 317 14 202 13 135 172 26 0 318 148 146 144 78 169 37 0 319 145 135 203 202 285 283 0 320 77 148 76 78 174 170 0 321 136 203 135 147 165 38 0 322 76 148 143 77 39 174 0 323 106 149 133 107 176 132 0 324 127 151 153 128 183 178 0 325 106 133 105 149 40 176 0 326 128 151 127 7 178 19 0 327 152 157 166 154 145 43 0 328 133 149 150 106 41 176 0 329 151 9 145 8 188 44 0 330 152 150 153 166 181 179 0 331 8 151 7 9 42 44 0 332 83 154 156 84 182 208 0 333 151 153 127 204 183 287 0 334 83 156 82 154 48 182 0 335 153 204 134 151 184 287 0 336 154 152 155 157 185 43 0 337 153 134 155 204 180 184 0 338 82 156 81 83 45 48 0 339 153 155 152 134 187 180 0 340 156 81 82 146 45 47 0 341 9 145 151 10 188 25 0 342 156 154 155 83 189 182 0 343 151 145 204 9 46 188 0 344 146 81 156 80 47 186 0 345 155 134 144 153 147 180 0 346 156 146 81 144 47 35 0 347 154 84 165 83 202 208 0 348 133 150 166 149 193 41 0 349 157 154 165 152 192 43 0 350 97 159 96 98 194 52 0 351 158 167 168 160 195 197 0 352 96 159 158 97 215 194 0 353 159 98 161 97 196 52 0 354 167 168 158 88 195 61 0 355 159 161 160 98 51 196 0 356 99 161 98 100 198 200 0

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176 176 357 160 163 162 161 201 203 0 358 98 161 159 99 196 198 0 359 100 164 161 101 53 56 0 360 162 167 160 87 199 59 0 361 161 100 164 99 53 200 0 362 165 86 162 85 54 212 0 363 161 163 160 164 203 55 0 364 165 85 86 84 212 57 0 365 164 101 102 100 206 56 0 366 163 166 157 164 211 209 0 367 161 164 163 100 55 53 0 368 103 164 102 133 204 210 0 369 165 162 163 86 205 54 0 370 164 102 103 101 204 206 0 371 165 84 85 154 57 202 0 372 164 166 163 133 209 58 0 373 165 154 84 157 202 192 0 374 103 133 164 104 210 24 0 375 157 165 163 154 207 192 0 376 164 133 166 103 58 210 0 377 162 87 167 86 59 214 0 378 159 160 158 161 213 51 0 379 162 86 87 165 214 54 0 380 167 88 168 87 61 66 0 381 158 96 159 95 215 50 0 382 167 87 88 162 66 59 0 383 169 176 50 177 222 85 0 384 172 178 177 173 235 223 0 385 50 169 176 51 222 68 0 386 174 54 170 53 70 79 0 387 170 173 172 171 225 227 0 388 174 53 54 52 79 82 0 389 63 173 62 178 220 81 0 390 54 170 174 55 70 69 0 391 62 173 171 63 78 220 0 392 169 52 174 51 218 226 0 393 173 178 172 63 223 81 0 394 169 51 52 50 226 68 0 395 64 178 63 180 224 86 0 396 172 174 170 169 219 80 0 397 63 178 173 64 81 224 0 398 174 169 52 172 218 80 0 399 171 173 170 62 227 78 0 400 52 174 169 53 218 82 0 401 181 44 45 175 228 89 0 402 190 197 185 196 273 229 0 403 44 175 43 181 83 89 0 404 49 176 48 50 216 84 0 405 177 180 182 178 241 233 0 406 48 176 47 49 230 216 0 407 176 50 169 49 222 84 0 408 178 180 177 64 233 86 0 409 181 176 179 47 87 232 0 410 65 180 64 66 234 238 0 411 177 169 172 176 217 85 0 412 64 180 178 65 86 234 0 413 47 176 181 48 232 230 0 414 179 182 184 177 245 239 0 415 181 47 176 46 232 236 0 416 180 186 182 66 88 90 0 417 179 176 177 181 231 87 0 418 180 66 186 65 90 238 0 419 46 181 45 47 240 236 0

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177 177 420 180 182 177 186 241 88 0 421 45 181 44 46 228 240 0 422 182 186 184 180 242 88 0 423 183 181 179 175 237 244 0 424 66 186 180 67 90 246 0 425 175 181 183 44 244 89 0 426 182 184 179 186 245 242 0 427 197 183 185 175 259 91 0 428 67 188 186 68 92 250 0 429 185 190 197 189 273 93 0 430 186 67 188 66 92 246 0 431 23 206 22 196 98 270 0 432 184 186 187 182 251 242 0 433 190 189 142 185 97 93 0 434 69 188 68 141 94 96 0 435 187 185 184 189 249 95 0 436 188 68 69 67 94 250 0 437 190 142 206 189 291 97 0 438 186 188 187 67 253 92 0 439 21 206 20 22 248 258 0 440 188 141 121 69 254 96 0 441 189 187 121 185 255 95 0 442 69 141 188 70 96 2 0 443 206 20 21 205 248 252 0 444 188 121 187 141 257 254 0 445 206 205 20 142 252 289 0 446 206 196 190 23 290 270 0 447 183 184 185 179 247 243 0 448 189 185 187 190 95 93 0 449 39 192 38 40 260 262 0 450 191 194 193 192 263 265 0 451 38 192 120 39 118 260 0 452 40 195 192 41 100 103 0 453 193 198 191 27 261 106 0 454 192 40 195 39 100 262 0 455 25 193 196 26 101 274 0 456 192 194 191 195 265 102 0 457 196 25 193 24 101 104 0 458 195 41 42 40 268 103 0 459 194 197 196 195 269 271 0 460 192 195 194 40 102 100 0 461 42 175 195 43 266 272 0 462 196 193 194 25 267 101 0 463 195 42 175 41 266 268 0 464 196 24 25 23 104 264 0 465 195 197 194 175 271 105 0 466 196 23 24 206 264 270 0 467 43 175 42 44 272 83 0 468 190 196 197 206 229 290 0 469 195 175 197 42 105 266 0 470 193 27 198 26 106 276 0 471 120 191 200 192 275 1 0 472 193 26 27 25 276 274 0 473 198 28 199 27 114 111 0 474 35 120 200 36 277 117 0 475 198 27 28 193 111 106 0 476 37 120 36 38 278 99 0 477 198 199 200 28 279 114 0 478 36 120 35 37 117 278 0 479 138 201 136 142 280 281 0 480 142 201 138 189 281 121 0 481 140 201 189 136 31 157 0 482 12 202 11 13 282 168 0

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178 178 483 145 202 135 11 283 146 0 484 11 202 145 12 146 282 0 485 145 203 204 135 284 285 0 486 135 203 145 136 285 165 0 487 147 203 136 134 38 171 0 488 134 204 203 153 286 184 0 489 151 204 153 145 287 46 0 490 145 204 151 203 46 284 0 491 19 205 18 20 288 256 0 492 142 205 206 138 289 33 0 493 18 205 17 19 162 288 0 494 190 206 196 142 290 291 0 495 142 206 190 205 291 289 0 496 22 206 21 23 258 98 0 1 192 191 120 2 69 70 141 3 168 89 91 4 132 124 122 5 113 114 124 6 114 115 124 7 115 116 125 8 116 117 125 9 2 126 119 10 117 118 126 11 118 119 126 12 1 2 119 13 117 126 125 14 4 131 123 15 124 132 113 16 115 125 124 17 3 123 126 18 149 129 127 19 7 151 128 20 109 110 129 21 130 129 132 22 5 6 128 23 110 111 132 24 103 104 133 25 9 10 145 26 14 135 202 27 135 138 136 28 74 137 139 29 15 16 138 30 72 73 139 31 140 201 189 32 71 72 141 33 138 205 142 34 137 75 143 35 144 146 156 36 10 11 145 37 78 146 148 38 136 147 203 39 143 76 148 40 105 106 133 41 150 133 149 42 7 8 151 43 152 154 157 44 8 9 151 45 81 82 156 46 151 145 204 47 156 146 81 48 82 83 156

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179 179 49 93 94 158 50 95 96 158 51 161 160 159 52 97 98 159 53 100 164 161 54 165 86 162 55 164 163 161 56 100 101 164 57 84 85 165 58 166 164 133 59 162 87 167 60 94 95 158 61 88 168 167 62 91 92 168 63 88 89 168 64 92 93 168 65 93 158 168 66 87 88 167 67 89 90 91 68 50 51 169 69 54 55 170 70 174 54 170 71 55 56 170 72 56 57 170 73 61 171 59 74 57 58 171 75 58 59 171 76 59 60 61 77 171 170 57 78 62 173 171 79 53 54 174 80 172 169 174 81 63 178 173 82 52 53 174 83 43 44 175 84 49 50 176 85 177 176 169 86 64 180 178 87 181 176 179 88 180 186 182 89 181 175 44 90 180 66 186 91 183 197 175 92 67 188 186 93 185 189 190 94 68 69 188 95 187 189 185 96 69 141 188 97 142 190 189 98 22 23 206 99 37 38 120 100 40 195 192 101 25 193 196 102 195 194 192 103 40 41 195 104 24 25 196 105 197 195 175 106 193 27 198 107 28 29 199 108 31 32 199 109 199 29 31 110 29 30 31 111 27 28 198

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180 180 112 33 34 200 113 32 33 199 114 199 198 28 115 34 35 200 116 33 200 199 117 35 36 120 118 120 38 192 119 191 198 200 120 70 71 141 121 142 189 201 122 129 110 132 123 132 122 130 124 4 5 131 125 123 122 125 126 111 112 132 127 122 124 125 128 112 113 132 129 126 123 125 130 3 4 123 131 2 3 126 132 106 107 149 133 149 127 150 134 6 7 128 135 128 127 130 136 107 108 149 137 127 129 130 138 149 108 129 139 131 128 130 140 5 128 131 141 123 131 122 142 108 109 129 143 131 130 122 144 104 105 133 145 152 157 166 146 145 11 202 147 144 155 134 148 14 15 135 149 136 143 147 150 15 138 135 151 137 143 136 152 74 75 137 153 137 136 140 154 16 17 138 155 140 139 137 156 73 74 139 157 136 201 140 158 17 205 138 159 121 141 139 160 141 72 139 161 140 121 139 162 17 18 205 163 140 189 121 164 75 76 143 165 135 136 203 166 78 79 146 167 144 134 147 168 12 13 202 169 144 148 146 170 77 78 148 171 134 203 147 172 13 14 202 173 147 148 144 174 76 77 148

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181 181 175 143 148 147 176 106 149 133 177 127 153 150 178 128 151 127 179 150 152 166 180 153 134 155 181 153 152 150 182 83 154 156 183 127 151 153 184 153 204 134 185 155 154 152 186 80 81 146 187 153 155 152 188 151 9 145 189 155 156 154 190 79 80 146 191 144 156 155 192 157 154 165 193 150 166 133 194 96 97 159 195 168 158 167 196 159 98 161 197 160 167 158 198 98 99 161 199 167 160 162 200 99 100 161 201 160 163 162 202 154 84 165 203 161 163 160 204 102 103 164 205 163 165 162 206 101 102 164 207 163 157 165 208 83 84 154 209 164 166 163 210 103 133 164 211 163 166 157 212 85 86 165 213 159 160 158 214 86 87 162 215 159 158 96 216 48 49 176 217 172 177 169 218 169 52 174 219 174 170 172 220 62 63 173 221 61 62 171 222 169 176 50 223 173 178 172 224 63 64 178 225 173 172 170 226 51 52 169 227 171 173 170 228 44 45 181 229 197 190 196 230 47 48 176 231 177 179 176 232 181 47 176 233 178 180 177 234 64 65 180 235 172 178 177 236 46 47 181 237 181 179 183

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182 182 238 65 66 180 239 177 182 179 240 45 46 181 241 177 180 182 242 182 186 184 243 179 184 183 244 183 175 181 245 184 179 182 246 66 67 186 247 185 183 184 248 20 21 206 249 185 184 187 250 67 68 188 251 184 186 187 252 205 20 206 253 187 186 188 254 121 188 141 255 189 187 121 256 19 20 205 257 188 121 187 258 21 22 206 259 185 197 183 260 38 39 192 261 198 191 193 262 39 40 192 263 191 194 193 264 23 24 196 265 192 194 191 266 42 175 195 267 194 196 193 268 41 42 195 269 194 197 196 270 23 196 206 271 195 197 194 272 42 43 175 273 185 190 197 274 25 26 193 275 191 200 120 276 26 27 193 277 200 35 120 278 36 37 120 279 200 198 199 280 136 138 201 281 138 142 201 282 11 12 202 283 202 135 145 284 203 204 145 285 145 135 203 286 203 134 204 287 151 204 153 288 18 19 205 289 206 142 205 290 206 196 190 291 190 142 206

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183Bedded Surface Input Files BOUNDARY.IN Pcp_File_Version=2 *** BLOCK ?: BOUNDARY INFORMATION ********************************************* NumBP NObs SeepF FreeD DrainF qQWLF 101 0 f t f f Node Number Array 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 Width Array 1.47302 2.94228 2.93131 2.91402 2.89197 2.8674 2.84329 2.82337 2.81219 2.81295 2.81892 2.81707 2.80283 2.78459 2.78353 2.81461 2.85877 2.89007 2.90095 2.8903 2.86518 2.83546 2.80658 2.78356 2.77569 2.79618 2.83817 2.87452 2.88673 2.87133 2.84174 2.81984 2.81433 2.82089 2.83461 2.85134 2.86771 2.88119 2.88997 1.44651 1.40625 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 2.8125 1.40625 0.445041 0.445042 0.445043 0.445043 0.445042 0.445042 0.445042 0.445041 0.445042 0.445043 0.445043 0.445042 0.445042 0.445042 0.445041 0.445042 0.445043 0.445043 0.445042 0.445042 0.445042 0.445041 0.445042 0.445043 0.445043 0.445042 0.445042 0.445042 Length of soil surface associated with transpiration 111.075 *** BLOCK ?: Solute transport boundary conditions ***************************** KodCB(1),KodCB(2),.....,KodCB(NumBP) -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 *** End of input file 'BOUNDARY.IN' ******************************************* DIMENSIO.IN Pcp_File_Version=2 NumNPD NumElD NumBPD MBandD NSeepD NumSPD NDrD NElDrD NMatD NObsD NSD 265 390 101 15 1 1 1 20 4 1 3

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184ATMOSPH.IN Pcp_File_Version=2 *** BLOCK I: ATMOSPHERIC INFORMATION ********************************** MaxAL (MaxAL = number of atmospheric data-records) 130 hCritS (max. allowed pressure head at the soil surface) 0 tAtm Prec rSoil rRoot hCritA rt ht cValue1 cValue2 cValue3 1 0 0.249 0 10000 0 0 0 0 0 0 0 0 0 0 0 2 0 0.289 0 10000 -0.001 0 0 646 0 0 0 0 0 2290.4 0 3 0 0.191 0 10000 0 0 0 0 0 0 0 0 0 0 0 4 1.1 0.084 0 10000 0 0 0 0 0 0 0 0 0 0 0 5 0.8 0.264 0 10000 0 0 0 0 0 0 0 0 0 0 0 6 4.9 0.024 0 10000 0 0 0 0 0 0 0 0 0 0 0 7 0 0.245 0 10000 -0.001 0 0 449.055 0 0 0 0 0 1592.11 0 8 0 0.272 0 10000 0 0 0 0 0 0 0 0 0 0 0 9 0 0.248 0 10000 0 0 0 0 0 0 0 0 0 0 0 10 0 0.265 0 10000 0 0 0 0 0 0 0 0 0 0 0 11 0.2 0.288 0 10000 0 0 0 0 0 0 0 0 0 0 0 12 0.1 0.254 0 10000 0 0 0 0 0 0 0 0 0 0 0 13 4.7 0.081 0 10000 0 0 0 0 0 0 0 0 0 0 0 14 0 0.1 0 10000 0 0 0 0 0 0 0 0 0 0 0 15 0 0.276 0 10000 0 0 0 0 0 0 0 0 0 0 0 16 0 0.242 0 10000 0 0 0 0 0 0 0 0 0 0 0 17 1.7 0.057 0 10000 0 0 0 0 0 0 0 0 0 0 0 18 0 0.072 0 10000 0 0 0 0 0 0 0 0 0 0 0

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185 19 0.1 0.09 0 10000 0 0 0 0 0 0 0 0 0 0 0 20 1.1 0.252 0 10000 0 0 0 0 0 0 0 0 0 0 0 21 0 0.3 0 10000 0 0 0 0 0 0 0 0 0 0 0 22 0 0.254 0 10000 0 0 0 0 0 0 0 0 0 0 0 23 0 0.354 0 10000 0 0 0 0 0 0 0 0 0 0 0 24 0 0.376 0 10000 0 0 0 0 0 0 0 0 0 0 0 25 0 0.308 0 10000 0 0 0 0 0 0 0 0 0 0 0 26 0 0.277 0 10000 0 0 0 0 0 0 0 0 0 0 0 27 0 0.289 0 10000 0 0 0 0 0 0 0 0 0 0 0 28 0 0.12 0 10000 0 0 0 0 0 0 0 0 0 0 0 29 0.1 0.16 0 10000 0 0 0 0 0 0 0 0 0 0 0 30 0.7 0.092 0 10000 0 0 0 0 0 0 0 0 0 0 0 31 0 0.303 0 10000 0 0 0 0 0 0 0 0 0 0 0 32 0 0.301 0 10000 0 0 0 0 0 0 0 0 0 0 0 33 0 0.218 0 10000 0 0 0 0 0 0 0 0 0 0 0 34 0 0.329 0 10000 0 0 0 0 0 0 0 0 0 0 0 35 0 0.294 0 10000 0 0 0 0 0 0 0 0 0 0 0 36 0.1 0.091 0 10000 -0.001 0 0 267.859 0 0 0 0 0 949.68 0 37 0 0.344 0 10000 0 0 0 0 0 0 0 0 0 0 0 38 0 0.285 0 10000 0 0 0 0 0 0 0 0 0 0 0 39 0 0.313 0 10000 0 0 0 0 0 0 0 0 0 0 0 40 0 0.368 0 10000 0 0 0 0 0 0 0 0 0 0 0 41 0 0.342 0 10000 0 0 0 0 0 0 0 0 0 0 0

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186 42 0 0.382 0 10000 0 0 0 0 0 0 0 0 0 0 0 43 0.3 0.195 0 10000 0 0 0 0 0 0 0 0 0 0 0 44 0 0.285 0 10000 0 0 0 0 0 0 0 0 0 0 0 45 0 0.128 0 10000 0 0 0 0 0 0 0 0 0 0 0 46 0.9 0.043 0 10000 0 0 0 0 0 0 0 0 0 0 0 47 0 0.328 0 10000 0 0 0 0 0 0 0 0 0 0 0 48 0 0.348 0 10000 0 0 0 0 0 0 0 0 0 0 0 49 0 0.351 0 10000 0 0 0 0 0 0 0 0 0 0 0 50 0 0.326 0 10000 0 0 0 0 0 0 0 0 0 0 0 51 0.6 0.292 0 10000 0 0 0 0 0 0 0 0 0 0 0 52 0 0.257 0 10000 0 0 0 0 0 0 0 0 0 0 0 53 6.9 0.047 0 10000 0 0 0 0 0 0 0 0 0 0 0 54 6.4 0.05 0 10000 0 0 0 0 0 0 0 0 0 0 0 55 0 0.158 0 10000 0 0 0 0 0 0 0 0 0 0 0 56 0 0.339 0 10000 0 0 0 0 0 0 0 0 0 0 0 57 0 0.371 0 10000 0 0 0 0 0 0 0 0 0 0 0 58 0 0.403 0 10000 0 0 0 0 0 0 0 0 0 0 0 59 0 0.395 0 10000 0 0 0 0 0 0 0 0 0 0 0 60 0 0.475 0 10000 0 0 0 0 0 0 0 0 0 0 0 61 0 0.482915 0.0020855 10000 0 0 0 0 0 0 0 0 0 0 0 62 0 0.444082 0.0019178 10000 0 0 0 0 0 0 0 0 0 0 0 63 0.6 0.280787 0.0012126 10000 0 0 0 0 0 0 0 0 0 0 0 64 0.3 0.397551 0.0034486 10000 -0.001 0 0 1599.27 0 0 0 0 0 5670.15 0

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187 65 0.8 0.466898 0.0061017 10000 0 0 0 0 0 0 0 0 0 0 0 66 0 0.444239 0.009761 10000 0 0 0 0 0 0 0 0 0 0 0 67 0.7 0.416087 0.0129129 10000 0 0 0 0 0 0 0 0 0 0 0 68 0 0.424895 0.0171054 10000 0 0 0 0 0 0 0 0 0 0 0 69 0 0.491593 0.0244068 10000 0 0 0 0 0 0 0 0 0 0 0 70 0.9 0.479603 0.0283972 10000 0 0 0 0 0 0 0 0 0 0 0 71 0 0.413453 0.0305472 10000 0 0 0 0 0 0 0 0 0 0 0 72 0.4 0.199283 0.0157165 10000 0 0 0 0 0 0 0 0 0 0 0 73 0 0.350062 0.032938 10000 0 0 0 0 0 0 0 0 0 0 0 74 0.9 0.388314 0.0446856 10000 0 0 0 0 0 0 0 0 0 0 0 75 0.9 0.389663 0.0533372 10000 0 0 0 0 0 0 0 0 0 0 0 76 0.5 0.374132 0.0618684 10000 -0.001 0 0 1638.66 0 0 0 0 0 5809.8 0 77 0.9 0.35456 0.0714402 10000 0 0 0 0 0 0 0 0 0 0 0 78 0.9 0.332278 0.079722 10000 0 0 0 0 0 0 0 0 0 0 0 79 0.9 0.396257 0.122744 10000 0 0 0 0 0 0 0 0 0 0 0 80 0.9 0.334312 0.129688 10000 0 0 0 0 0 0 0 0 0 0 0 81 0.9 0.323809 0.157191 10000 0 0 0 0 0 0 0 0 0 0 0 82 2.5 0.278477 0.169523 10000 0 0 0 0 0 0 0 0 0 0 0 83 0.9 0.284262 0.189738 10000 0 0 0 0 0 0 0 0 0 0 0 84 0 0.232518 0.182482 10000 0 0 0 0 0 0 0 0 0 0 0 85 0.2 0.172411 0.146589 10000 0 0 0 0 0 0 0 0 0 0 0 86 1 0.215676 0.201324 10000 0 0 0 0 0 0 0 0 0 0 0 87 0.9 0.193082 0.193918 10000 0 0 0 0 0 0 0 0 0 0 0

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188 88 0.9 0.237761 0.266239 10000 0 0 0 0 0 0 0 0 0 0 0 89 0.9 0.191996 0.235004 10000 0 0 0 0 0 0 0 0 0 0 0 90 0.9 0.194315 0.253685 10000 0 0 0 0 0 0 0 0 0 0 0 91 0.9 0.182315 0.251685 10000 0 0 0 0 0 0 0 0 0 0 0 92 1.9 0.104176 0.148824 10000 0 0 0 0 0 0 0 0 0 0 0 93 2.1 0.0683525 0.0976475 10000 0 0 0 0 0 0 0 0 0 0 0 94 0.1 0.157923 0.224077 10000 0 0 0 0 0 0 0 0 0 0 0 95 0.3 0.0996166 0.140383 10000 0 0 0 0 0 0 0 0 0 0 0 96 0 0.189613 0.265387 10000 0 0 0 0 0 0 0 0 0 0 0 97 1 0.184097 0.255903 10000 0 0 0 0 0 0 0 0 0 0 0 98 3.6 0.228103 0.314897 10000 0 0 0 0 0 0 0 0 0 0 0 99 0.9 0.227752 0.312248 10000 0 0 0 0 0 0 0 0 0 0 0 100 0.5 0.199023 0.270977 10000 0 0 0 0 0 0 0 0 0 0 0 101 0.7 0.268696 0.363304 10000 0 0 0 0 0 0 0 0 0 0 0 102 0.7 0.239997 0.320003 10000 0 0 0 0 0 0 0 0 0 0 0 103 0.7 0.253867 0.336133 10000 0 0 0 0 0 0 0 0 0 0 0 104 0.7 0.231989 0.305011 10000 0 0 0 0 0 0 0 0 0 0 0 105 0.9 0.226884 0.294116 10000 0 0 0 0 0 0 0 0 0 0 0 106 0.9 0.251841 0.324159 10000 0 0 0 0 0 0 0 0 0 0 0 107 0.9 0.240201 0.304799 10000 0 0 0 0 0 0 0 0 0 0 0 108 0.8 0.236355 0.295645 10000 0 0 0 0 0 0 0 0 0 0 0 109 0.8 0.217652 0.268348 10000 0 0 0 0 0 0 0 0 0 0 0 110 0.8 0.235201 0.285799 10000 0 0 0 0 0 0 0 0 0 0 0

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189 111 0.8 0.185212 0.221788 10000 0 0 0 0 0 0 0 0 0 0 0 112 0.8 0.2137 0.2503 10000 0 0 0 0 0 0 0 0 0 0 0 113 0.9 0.26045 0.30055 10000 0 0 0 0 0 0 0 0 0 0 0 114 0.8 0.253727 0.286273 10000 0 0 0 0 0 0 0 0 0 0 0 115 0.7 0.283236 0.314764 10000 0 0 0 0 0 0 0 0 0 0 0 116 0 0.278986 0.303014 10000 0 0 0 0 0 0 0 0 0 0 0 117 0 0.235295 0.249705 10000 0 0 0 0 0 0 0 0 0 0 0 118 0.6 0.252374 0.261626 10000 0 0 0 0 0 0 0 0 0 0 0 119 0.6 0.270329 0.273671 10000 0 0 0 0 0 0 0 0 0 0 0 120 0 0.295218 0.291782 10000 0 0 0 0 0 0 0 0 0 0 0 121 0.4 0.286182 0.273818 10000 0 0 0 0 0 0 0 0 0 0 0 122 0.4 0.324807 0.303193 10000 0 0 0 0 0 0 0 0 0 0 0 123 0.4 0.332148 0.299852 10000 0 0 0 0 0 0 0 0 0 0 0 124 0 0.33403 0.29397 10000 0 0 0 0 0 0 0 0 0 0 0 125 0 0.306591 0.258409 10000 0 0 0 0 0 0 0 0 0 0 0 126 0.2 0.338003 0.274997 10000 0 0 0 0 0 0 0 0 0 0 0 127 0 0.310517 0.241483 10000 0 0 0 0 0 0 0 0 0 0 0 128 0 0.358684 0.266316 10000 0 0 0 0 0 0 0 0 0 0 0 129 0 0.318505 0.225495 10000 0 0 0 0 0 0 0 0 0 0 0 130 0.8 0.159253 0.112747 10000 0 0 0 0 0 0 0 0 0 0 0 *** END OF INPUT FILE 'ATMOSPH.IN' *************************************

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190SELECTOR.IN Pcp_File_Version=2 *** BLOCK A: BASIC INFORMATION ***************************************** Heading Welcome to HYDRUS-2D LUnit TUnit MUnit (indicated units are obligatory for all input data) cm days -mg Kat (0:horizontal plane, 1:axisymmetric vertical flow, 2:vertical plane) 2 MaxIt TolTh TolH InitH/W (max. number of iterations and tolerances) 10000 0.0001 0.1 t lWat lChem lSink Short Flux lScrn AtmIn lTemp lWTDep lEquil lExtGen lInv t t t f t t t f f t t f *** BLOCK B: MATERIAL INFORMATION ************************************** NMat NLay hTab1 hTabN 4 5 1e-006 10000 Model Hysteresis 2 0 thr ths Alfa n Ks l 0.03 0.3883 0.061 0.753 4515 2 0.03 0.3883 0.061 0.753 4515 2 0.03 0.3526 0.053 0.754 3759 2 0.03 0.3526 0.053 0.754 3759 2 *** BLOCK C: TIME INFORMATION ****************************************** dt dtMin dtMax DMul DMul2 ItMin ItMax MPL 0.001 1e-005 0.001 1.7 0.7 3 7 100 tInit tMax 0 130 TPrint(1),TPrint(2),...,TPrint(MPL) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 71 73 75 77 79 81 82 84 86 88 90 92 94 96 98

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191 100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 *** BLOCK G: SOLUTE TRANSPORT INFORMATION ***************************************************** Epsi lUpW lArtD lTDep cTolA cTolR MaxItC PeCr Nu.of Solutes Tortuosity 1 f f f 0 0 1 1 3 t Bulk.d. DisperL. DisperT Frac ThImob (1..NMat) 1.48 10 10 1 0 1.48 10 10 1 0 1.56 10 10 1 0 1.56 10 10 1 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 0.001 0 1 0 0 0 0 0.001 0 0 0 0 0 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 0 0 1 0 0 0 0 0.11 0 0 0 0 0 0 DifW DifG n-th solute 1.2 0 Ks Nu Beta Henry SnkL1 SnkS1 SnkG1 SnkL1' SnkS1' SnkG1' S nkL0 SnkS0 SnkG0 Alfa 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0

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192 cTop cBot 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 tPulse 1 *** BLOCK G: ROOT WATER UPTAKE INFORMATION ***************************** Model (0 Feddes, 1 S shape) 0 P0 P2H P2L P3 r2H r2L -10 -320 -600 -6000 0.5 0.1 POptm(1),POptm(2),...,POptm(NMat) -25 -25 -25 -25 Solute Reduction f *** END OF INPUT FILE 'SELECTOR.IN' ************************************

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193MESHTRIA.000 1 265 656 390 142 1 90 60 37.7346 0 2 87.3874 61.3614 37.7346 0 3 84.7926 62.7406 37.8704 0 4 82.2337 64.1555 38.1531 0 5 79.7284 65.6241 38.6044 0 6 77.2948 67.1642 39.255 0 7 74.9507 68.7936 40.1433 0 8 72.7139 70.5302 41.3115 0 9 70.6025 72.3919 42.8043 0 10 68.6342 74.3965 44.6627 0 11 66.8008 76.5346 46.5268 0 12 65.0353 78.7353 47.1346 0 13 63.2623 80.9189 45.6801 0 14 61.4064 83.0059 43.1991 0 15 59.3922 84.9167 40.0134 0 16 57.1456 86.5723 36.7486 0 17 54.6474 87.9198 33.8152 0 18 51.9566 88.9438 31.3613 0 19 49.1382 89.6316 29.5961 0 20 46.2572 89.9705 28.8002 0 21 43.3776 89.9489 28.8002 0 22 40.5529 89.5657 29.2684 0 23 37.8315 88.825 30.9838 0 24 35.2617 87.7314 33.7464 0 25 32.8919 86.2889 37.3344 0 26 30.7589 84.5106 41.4723 0 27 28.8222 82.4673 45.2235 0 28 27.0091 80.2541 47.833 0 29 25.2464 77.9664 48.7269 0 30 23.4613 75.6994 46.9529 0 31 21.5808 73.5483 44.3631 0 32 19.5584 71.5741 42.1071 0 33 17.4035 69.7653 40.2889 0 34 15.1326 68.1013 38.8621 0 35 12.7623 66.5615 37.7767 0 36 10.3093 65.1251 36.9822 0 37 7.78992 63.7714 36.4321 0 38 5.22089 62.4798 36.0884 0 39 2.61872 61.2296 35.9235 0 40 0 60 35.9235 0 41 -2.71051e-020 57.2727 54.5454 0 42 0 54.5455 54.5454 0 43 0 51.8182 54.5454 0 44 0 49.0909 54.5454 0 45 1.35525e-020 46.3636 54.5454 0 46 6.77626e-021 43.6364 54.5454 0 47 -2.71051e-020 40.9091 54.5454 0 48 0 38.1818 54.5454 0 49 0 35.4545 54.5454 0 50 0 32.7273 54.5454 0 51 0 30 54.5454 0 52 0 27.2727 54.5454 0 53 0 24.5455 54.5454 0 54 3.38813e-021 21.8182 54.5454 0 55 0 19.0909 54.5454 0 56 0 16.3636 54.5454 0 57 0 13.6364 54.5454 0 58 3.38813e-021 10.9091 54.5454 0 59 0 8.18182 54.5454 0 60 1.69407e-021 5.45454 54.5454 0 61 8.47033e-022 2.72727 54.5454 0 62 0 0 28.125 0 63 2.8125 -4.23516e-022 28.125 0 64 5.625 -8.47033e-022 28.125 0 65 8.4375 8.47033e-021 28.125 0 66 11.25 -1.69407e-021 28.125 0 67 14.0625 0 28.125 0

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194 68 16.875 1.69407e-020 28.125 0 69 19.6875 1.01644e-020 28.125 0 70 22.5 -3.38813e-021 28.125 0 71 25.3125 3.38813e-020 28.125 0 72 28.125 0 28.125 0 73 30.9375 0 28.125 0 74 33.75 3.38813e-020 28.125 0 75 36.5625 0 28.125 0 76 39.375 2.03288e-020 28.125 0 77 42.1875 0 28.125 0 78 45 -6.77626e-021 28.125 0 79 47.8125 6.77626e-020 28.125 0 80 50.625 6.77626e-020 28.125 0 81 53.4375 0 28.125 0 82 56.25 0 28.125 0 83 59.0625 2.71051e-020 28.125 0 84 61.875 0 28.125 0 85 64.6875 4.06576e-020 28.125 0 86 67.5 6.77626e-020 28.125 0 87 70.3125 0 28.125 0 88 73.125 0 28.125 0 89 75.9375 -6.77626e-020 28.125 0 90 78.75 4.06576e-020 28.125 0 91 81.5625 6.77626e-020 28.125 0 92 84.375 0 28.125 0 93 87.1875 0 28.125 0 94 90 -1.35525e-020 28.125 0 95 90 2.85715 57.1426 0 96 90 5.71428 57.1426 0 97 90 8.57143 57.1429 0 98 90 11.4286 57.1429 0 99 90 14.2857 57.1426 0 100 90 17.1429 57.1426 0 101 90 20 57.1429 0 102 90 22.8571 57.1426 0 103 90 25.7143 57.1426 0 104 90 28.5714 57.1429 0 105 90 31.4286 57.1429 0 106 90 34.2857 57.1426 0 107 90 37.1429 57.1426 0 108 90 40 57.1429 0 109 90 42.8571 57.1426 0 110 90 45.7143 57.1426 0 111 90 48.5714 57.1429 0 112 90 51.4286 57.1429 0 113 90 54.2857 57.1426 0 114 90 57.1429 57.1426 0 115 53 84 8.73399 0 116 52.901 84.4339 7.49174 0 117 52.6235 84.7818 5.56711 0 118 52.2225 84.9749 4.45042 0 119 51.7775 84.9749 4.45042 0 120 51.3765 84.7818 5.56709 0 121 51.099 84.4339 7.49175 0 122 51 84 8.73399 0 123 51.099 83.5661 7.49174 0 124 51.3765 83.2182 5.56711 0 125 51.7775 83.0251 4.45042 0 126 52.2225 83.0251 4.45042 0 127 52.6235 83.2182 5.56709 0 128 52.901 83.5661 7.49175 0 129 39 84 8.73399 0 130 38.901 84.4339 7.49174 0 131 38.6235 84.7818 5.56711 0 132 38.2225 84.9749 4.45042 0 133 37.7775 84.9749 4.45042 0 134 37.3765 84.7818 5.56709 0 135 37.099 84.4339 7.49175 0 136 37 84 8.73399 0 137 37.099 83.5661 7.49174 0 138 37.3765 83.2182 5.56711 0

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195 139 37.7775 83.0251 4.45042 0 140 38.2225 83.0251 4.45042 0 141 38.6235 83.2182 5.56709 0 142 38.901 83.5661 7.49175 0 143 34.9967 64.7309 43.6497 3 144 6.15428 2.56221 38.1007 3 145 11.9901 2.75945 34.5996 3 146 8.80991 6.07518 43.6986 3 147 17.0279 2.4242 32.5304 3 148 16.3703 6.08173 38.9784 3 149 11.8224 10.4436 46.8659 3 150 21.9885 3.71081 33.7385 3 151 22.8169 9.09533 40.7875 3 152 17.5983 15.6777 48.3773 3 153 27.379 4.30782 33.8492 3 154 32.9092 7.74126 37.4607 3 155 30.0016 12.6089 43.0062 3 156 32.9291 3.02961 31.8187 3 157 39.1382 4.79634 33.6165 3 158 34.4721 17.9967 46.7905 3 159 64.5054 9.4017 41.4407 3 160 75.4175 2.59867 34.6928 3 161 82.6437 2.34473 38.0955 3 162 76.6206 9.21441 46.9738 3 163 63.6311 3.78364 33.8894 3 164 70.6094 5.67338 38.8199 3 165 79.8077 5.61457 44.1925 3 166 69.1224 2.16965 32.2236 3 167 41.7119 11.3933 40.6014 3 168 45.5717 5.46091 34.3129 3 169 62.8184 15.8035 46.4963 3 170 51.2946 3.73903 32.5337 3 171 53.088 10.2377 39.898 3 172 75.4268 13.7887 49.6434 3 173 57.7067 4.97426 34.5449 3 174 39.7112 52.8527 47.7586 3 175 21.1083 35.5583 52.5769 3 176 40.862 32.5913 51.7446 3 177 22.1099 29.0758 52.2823 3 178 65.5657 23.9723 51.5099 3 179 43.3603 25.2354 50.2993 3 180 76.3692 19.8059 52.4307 3 181 20.4285 22.623 51.064 3 182 50.2783 17.8132 46.1941 3 183 63.7016 31.5835 52.8908 3 184 36.9048 40.0124 51.2295 3 185 63.3903 49.8053 49.5349 3 186 16.6475 47.4323 51.2897 3 187 48.7549 46.1783 49.9215 3 188 24.2098 42.1662 51.5798 3 189 63.0152 41.4608 51.8864 3 190 23.586 63.8553 42.1562 3 191 17.0163 56.7748 45.6047 3 192 43.2768 59.5885 45.4941 3 193 32.2637 58.7442 45.3063 3 194 52.2151 54.0056 47.474 3 195 55.544 80.4952 32.4223 3 196 49.9368 84.7611 10.5183 3 197 42.3197 83.1486 14.8374 3 198 49.6086 82.9561 11.3272 3 199 51.2685 82.8358 8.78395 3 200 49.7596 82.1971 15.6582 3 201 50.028 83.5256 9.44729 3 202 52.939 83.0242 11.1128 3 203 54.3926 84.6644 18.0561 3 204 52.9148 85.5872 15.3378 3 205 51.2279 86.5238 19.7008 3 206 42.9609 81.4138 21.4641 3 207 26.4128 68.5257 42.3433 3 208 64.3495 56.9905 46.2618 3 209 63.0003 69.2322 42.8906 3

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196 210 44.3231 78.9771 30.8264 3 211 52.3325 77.1855 37.5551 3 212 39.6677 75.7622 39.6486 3 213 52.1955 72.3763 42.1631 3 214 36.7034 71.0889 42.8683 3 215 45.6926 66.3335 43.6818 3 216 48.9372 80.5721 25.0018 3 217 37.1158 85.5256 15.2429 3 218 33.821 81.4713 30.869 3 219 39.3826 81.8027 18.5968 3 220 36.8072 79.622 32.1287 3 221 40.2999 82.886 12.7471 3 222 44.9161 83.0865 15.9573 3 223 46.9657 82.2287 17.4995 3 224 47.7684 83.3906 13.3043 3 225 34.4614 83.1782 24.6118 3 226 36.5844 83.4169 12.6455 3 227 38.555 82.785 9.51015 3 228 37.0791 82.2458 17.0519 3 229 35.7301 84.5646 17.6077 3 230 46.707 87.3447 21.5131 3 231 43.6655 87.5587 22.126 3 232 40.744 87.4163 22.5435 3 233 41.6551 85.907 16.2167 3 234 38.7823 86.4979 19.7139 3 235 39.1338 85.3464 11.1166 3 236 40.1199 84.8482 10.6959 3 237 44.9694 85.6106 16.4496 3 238 49.3104 87.392 22.4731 3 239 48.457 85.8227 15.8515 3 240 50.9038 85.3281 11.0004 3 241 46.1948 84.2425 14.2363 3 242 43.4742 84.2036 14.2796 3 243 47.6813 84.9112 13.7049 3 244 42.1645 84.8769 13.6919 3 245 48.9108 84.1253 11.4751 3 246 40.6352 83.9807 11.2042 3 247 8.18619 58.1654 44.3312 3 248 51.2287 38.0434 51.591 3 249 76.474 37.9087 54.4574 3 250 52.1611 82.0967 17.4614 3 251 53.6455 83.6791 13.5742 3 252 53.8771 60.8258 45.1082 3 253 76.1292 46.5269 52.889 3 254 25.9308 52.9279 47.9766 3 255 55.305 82.9969 24.2842 3 256 76.9352 54.8115 48.3971 3 257 74.9949 60.9124 42.6041 3 258 14.5727 61.7658 41.0646 3 259 12.0257 52.7553 49.7388 3 260 63.9377 63.0851 43.7438 3 261 70.9832 65.8578 41.7456 3 262 55.4105 66.567 43.4803 3 263 11.0922 41.0532 53.0948 3 264 23.0991 58.8699 44.4367 3 265 32.9 47.0557 49.8818 3 1 1 2 114 0 100 0 1 2 2 3 257 0 95 0 1 3 3 4 257 0 275 0 1 4 4 5 257 0 372 0 1 5 5 6 261 0 101 0 1 6 6 7 261 0 380 0 1 7 7 8 261 0 284 0 1 8 8 9 209 0 280 0 1 9 9 10 209 0 290 0 1 10 10 11 213 0 304 0 1 11 11 12 211 0 246 0 1 12 12 13 195 0 256 0 1 13 13 14 195 0 254 0 1 14 14 15 255 0 368 0 1

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197 15 15 16 203 0 264 0 1 16 16 17 204 0 266 0 1 17 17 18 205 0 268 0 1 18 18 19 238 0 126 0 1 19 19 20 230 0 317 0 1 20 20 21 231 0 319 0 1 21 21 22 231 0 321 0 1 22 22 23 232 0 325 0 1 23 23 24 234 0 327 0 1 24 24 25 217 0 292 0 1 25 25 26 229 0 120 0 1 26 26 27 225 0 307 0 1 27 27 28 218 0 110 0 1 28 28 29 220 0 112 0 1 29 29 30 212 0 102 0 1 30 30 31 214 0 104 0 1 31 31 32 207 0 106 0 1 32 32 33 207 0 286 0 1 33 33 34 207 0 93 0 1 34 34 35 190 0 144 0 1 35 35 36 258 0 2 0 1 36 36 37 258 0 1 0 1 37 37 38 258 0 3 0 1 38 38 39 247 0 351 0 1 39 39 40 247 0 4 0 1 40 40 41 247 0 71 0 1 41 41 42 247 0 376 0 1 42 42 43 259 0 239 0 1 43 43 44 259 0 54 0 1 44 44 45 186 0 229 0 1 45 45 46 263 0 385 0 1 46 46 47 263 0 68 0 1 47 47 48 263 0 55 0 1 48 48 49 263 0 208 0 1 49 49 50 175 0 57 0 1 50 50 51 177 0 211 0 1 51 51 52 177 0 215 0 1 52 52 53 181 0 61 0 1 53 53 54 181 0 174 0 1 54 54 55 181 0 168 0 1 55 55 56 152 0 156 0 1 56 56 57 152 0 23 0 1 57 57 58 149 0 20 0 1 58 58 59 149 0 146 0 1 59 59 60 146 0 11 0 1 60 60 61 144 0 8 0 1 61 61 62 63 0 6 0 1 62 62 63 61 0 6 0 1 63 63 64 144 0 9 0 1 64 64 65 144 0 10 0 1 65 65 66 145 0 13 0 1 66 66 67 145 0 15 0 1 67 67 68 147 0 16 0 1 68 68 69 147 0 148 0 1 69 69 70 150 0 19 0 1 70 70 71 150 0 158 0 1 71 71 72 153 0 22 0 1 72 72 73 156 0 164 0 1 73 73 74 156 0 25 0 1 74 74 75 156 0 27 0 1 75 75 76 157 0 170 0 1 76 76 77 157 0 28 0 1 77 77 78 168 0 48 0 1 78 78 79 170 0 198 0 1 79 79 80 170 0 200 0 1 80 80 81 170 0 204 0 1 81 81 82 170 0 50 0 1 82 82 83 173 0 184 0 1 83 83 84 163 0 186 0 1 84 84 85 163 0 190 0 1 85 85 86 166 0 178 0 1

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198 86 86 87 166 0 46 0 1 87 87 88 166 0 41 0 1 88 88 89 160 0 31 0 1 89 89 90 160 0 33 0 1 90 90 91 161 0 39 0 1 91 91 92 161 0 36 0 1 92 92 93 161 0 37 0 1 93 93 94 95 0 38 0 1 94 94 95 93 0 38 0 1 95 95 96 161 0 181 0 1 96 96 97 165 0 180 0 1 97 97 98 162 0 188 0 1 98 98 99 172 0 182 0 1 99 99 100 172 0 202 0 1 100 100 101 180 0 196 0 1 101 101 102 180 0 221 0 1 102 102 103 180 0 60 0 1 103 103 104 178 0 58 0 1 104 104 105 183 0 63 0 1 105 105 106 249 0 69 0 1 106 106 107 249 0 355 0 1 107 107 108 249 0 235 0 1 108 108 109 249 0 227 0 1 109 109 110 253 0 231 0 1 110 110 111 253 0 244 0 1 111 111 112 253 0 96 0 1 112 112 113 256 0 274 0 1 113 113 114 256 0 98 0 1 114 114 1 2 0 100 0 1 115 115 116 0 203 0 261 -1 116 116 117 0 203 0 263 -1 117 117 118 0 204 0 88 -1 118 118 119 0 204 0 89 -1 119 119 120 0 240 0 136 -1 120 120 121 0 196 0 135 -1 121 121 122 0 196 0 78 -1 122 122 123 0 201 0 338 -1 123 123 124 0 201 0 345 -1 124 124 125 0 199 0 306 -1 125 125 126 0 199 0 81 -1 126 126 127 0 202 0 262 -1 127 127 128 0 202 0 360 -1 128 128 115 0 251 0 359 -1 129 129 130 0 246 0 142 -1 130 130 131 0 236 0 140 -1 131 131 132 0 235 0 323 -1 132 132 133 0 217 0 293 -1 133 133 134 0 217 0 132 -1 134 134 135 0 229 0 124 -1 135 135 136 0 229 0 118 -1 136 136 137 0 226 0 119 -1 137 137 138 0 226 0 310 -1 138 138 139 0 228 0 309 -1 139 139 140 0 227 0 122 -1 140 140 141 0 227 0 111 -1 141 141 142 0 221 0 250 -1 142 142 129 0 246 0 347 -1 143 258 38 247 37 374 3 0 144 36 258 35 37 2 1 0 145 247 41 42 40 376 71 0 146 40 247 39 41 4 71 0 147 190 143 207 193 5 240 0 148 215 252 262 192 273 361 0 149 61 63 144 62 7 6 0 150 144 63 64 61 9 7 0 151 64 144 63 65 9 10 0 152 144 61 63 60 7 8 0 153 144 65 145 64 12 10 0 154 65 145 144 66 12 13 0 155 144 60 61 146 8 14 0 156 145 66 67 65 15 13 0

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199 157 67 145 66 147 15 147 0 158 145 144 65 146 12 149 0 159 147 145 67 148 147 151 0 160 145 148 146 147 153 151 0 161 148 146 145 149 153 155 0 162 150 148 147 151 18 157 0 163 148 151 149 150 159 157 0 164 151 149 148 152 159 161 0 165 153 151 150 154 21 163 0 166 152 151 155 149 165 161 0 167 151 155 152 154 165 167 0 168 156 154 153 157 160 169 0 169 155 154 167 151 171 167 0 170 154 167 155 157 171 173 0 171 167 157 168 154 192 173 0 172 167 158 155 182 47 175 0 173 182 158 167 179 175 220 0 174 162 159 164 172 183 203 0 175 173 159 171 163 177 30 0 176 161 160 90 165 34 191 0 177 166 160 164 88 179 32 0 178 96 161 95 165 181 40 0 179 161 90 91 160 39 34 0 180 91 161 90 92 39 36 0 181 160 90 161 89 34 33 0 182 95 161 93 96 35 181 0 183 92 161 91 93 36 37 0 184 93 161 92 95 37 35 0 185 95 93 94 161 38 35 0 186 160 89 90 88 33 31 0 187 159 164 162 163 183 185 0 188 164 163 166 159 44 185 0 189 165 164 160 162 189 187 0 190 164 160 165 166 189 179 0 191 168 167 157 171 192 197 0 192 171 167 168 182 197 195 0 193 168 171 167 170 197 199 0 194 171 170 173 168 51 199 0 195 159 169 171 172 205 201 0 196 172 159 162 169 203 201 0 197 187 194 174 185 228 207 0 198 194 174 187 192 228 243 0 199 184 175 176 188 226 384 0 200 184 187 265 248 230 353 0 201 183 176 179 248 224 354 0 202 184 176 248 175 210 226 0 203 179 183 176 178 224 212 0 204 179 176 177 183 214 224 0 205 179 178 183 182 212 218 0 206 182 178 179 169 218 62 0 207 179 182 178 158 218 220 0 208 158 179 181 182 222 220 0 209 174 187 194 265 228 389 0 210 265 187 174 184 389 230 0 211 265 184 187 188 230 236 0 212 188 184 265 175 236 384 0 213 247 42 259 41 238 376 0 214 258 190 35 264 237 70 0 215 258 264 190 191 70 387 0 216 193 143 190 192 240 72 0 217 193 192 143 174 72 245 0 218 174 192 193 194 245 243 0 219 200 223 216 198 115 255 0 220 198 224 223 201 83 302 0 221 239 243 196 237 331 249 0 222 237 243 239 241 249 344 0 223 199 198 200 124 257 253 0 224 250 199 200 126 357 258 0 225 200 199 198 250 257 357 0 226 200 198 223 199 255 257 0 227 115 203 116 251 261 86 0

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200 228 251 203 115 255 86 84 0 229 128 202 251 127 80 360 0 230 15 203 255 16 87 264 0 231 255 251 202 203 369 84 0 232 204 117 203 118 265 88 0 233 240 204 205 119 337 267 0 234 238 205 18 239 134 334 0 235 240 205 239 204 269 337 0 236 216 206 210 223 291 271 0 237 223 206 216 222 271 305 0 238 143 215 214 192 289 145 0 239 143 214 207 215 277 289 0 240 3 257 2 4 95 275 0 241 257 260 208 261 373 288 0 242 256 114 2 113 99 98 0 243 2 257 256 3 97 95 0 244 256 2 257 114 97 99 0 245 256 257 208 2 370 97 0 246 2 114 1 256 100 99 0 247 211 210 212 216 281 279 0 248 216 210 211 206 279 291 0 249 212 211 210 213 281 283 0 250 213 212 214 211 285 283 0 251 214 213 212 215 285 287 0 252 215 214 143 213 289 287 0 253 229 217 25 134 316 315 0 254 132 235 217 131 329 323 0 255 220 228 218 219 297 295 0 256 228 218 220 225 297 123 0 257 220 219 228 206 295 303 0 258 206 219 220 221 303 299 0 259 206 197 221 222 300 301 0 260 222 197 206 242 301 346 0 261 223 222 206 224 305 114 0 262 225 229 26 226 117 308 0 263 26 229 25 225 120 117 0 264 229 226 136 225 125 308 0 265 229 136 135 226 118 125 0 266 226 225 228 229 312 308 0 267 226 138 137 228 310 121 0 268 228 227 139 219 311 314 0 269 135 229 136 134 118 124 0 270 237 230 231 239 332 318 0 271 239 230 237 238 318 336 0 272 232 231 22 233 128 322 0 273 237 231 233 230 320 332 0 274 233 232 234 231 324 322 0 275 234 233 232 235 324 326 0 276 235 234 217 233 131 326 0 277 236 235 131 233 330 328 0 278 239 238 230 205 336 334 0 279 242 241 237 222 340 251 0 280 242 222 241 197 251 346 0 281 241 237 242 243 340 344 0 282 237 242 241 244 340 342 0 283 241 224 245 222 348 350 0 284 35 190 34 258 144 237 0 285 143 192 215 193 145 72 0 286 207 190 143 34 5 272 0 287 146 60 144 59 14 11 0 288 67 147 145 68 147 16 0 289 146 59 60 149 11 17 0 290 69 147 68 150 148 152 0 291 145 146 144 148 149 153 0 292 68 147 67 69 16 148 0 293 149 59 146 58 17 146 0 294 147 148 145 150 151 18 0 295 149 58 59 57 146 20 0 296 69 150 147 70 152 19 0 297 146 144 145 60 149 14 0 298 147 150 148 69 18 152 0

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201 299 150 71 153 70 154 158 0 300 148 149 146 151 155 159 0 301 70 150 69 71 19 158 0 302 149 57 58 152 20 150 0 303 150 151 148 153 157 21 0 304 152 57 149 56 150 23 0 305 71 153 150 72 154 22 0 306 149 146 148 59 155 17 0 307 150 153 151 71 21 154 0 308 153 156 154 72 160 24 0 309 151 154 155 153 167 163 0 310 72 153 71 156 22 24 0 311 152 56 57 55 23 156 0 312 153 154 151 156 163 160 0 313 152 158 181 155 29 26 0 314 73 156 72 74 164 25 0 315 152 149 151 57 161 150 0 316 72 156 153 73 24 164 0 317 156 75 157 74 166 27 0 318 154 157 167 156 173 169 0 319 74 156 73 75 25 27 0 320 152 55 56 181 156 162 0 321 156 157 154 75 169 166 0 322 152 181 55 158 162 29 0 323 76 157 75 77 170 28 0 324 155 152 151 158 165 26 0 325 75 157 156 76 166 170 0 326 77 168 157 78 172 48 0 327 167 155 154 158 171 47 0 328 77 157 76 168 28 172 0 329 181 55 152 54 162 168 0 330 167 182 158 171 175 195 0 331 181 54 55 53 168 174 0 332 163 83 84 173 186 53 0 333 159 171 173 169 177 205 0 334 83 173 82 163 184 53 0 335 166 88 160 87 32 41 0 336 160 165 164 161 189 191 0 337 166 87 88 86 41 46 0 338 97 165 96 162 180 45 0 339 88 160 166 89 32 31 0 340 96 165 161 97 40 180 0 341 99 172 98 100 182 202 0 342 159 163 164 173 185 30 0 343 98 172 162 99 42 182 0 344 163 173 83 159 53 30 0 345 164 162 159 165 183 187 0 346 84 163 83 85 186 190 0 347 166 85 86 163 178 43 0 348 165 162 164 97 187 45 0 349 85 163 84 166 190 43 0 350 98 162 97 172 188 42 0 351 164 166 160 163 179 44 0 352 97 162 165 98 45 188 0 353 166 163 85 164 43 44 0 354 161 165 160 96 191 40 0 355 86 166 85 87 178 46 0 356 157 168 167 77 192 172 0 357 182 171 169 167 193 195 0 358 158 155 167 152 47 26 0 359 78 170 168 79 194 198 0 360 169 182 171 178 193 62 0 361 78 168 77 170 48 194 0 362 101 180 100 102 196 221 0 363 168 170 171 78 199 194 0 364 172 180 169 100 52 49 0 365 170 80 81 79 204 200 0 366 171 169 182 159 193 205 0 367 170 79 80 78 200 198 0 368 170 82 173 81 176 50 0 369 172 169 159 180 201 52 0

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202 370 81 170 80 82 204 50 0 371 180 100 101 172 196 49 0 372 171 173 159 170 177 51 0 373 172 100 180 99 49 202 0 374 173 170 82 171 176 51 0 375 162 172 159 98 203 42 0 376 82 173 170 83 176 184 0 377 186 45 263 44 206 229 0 378 185 194 187 208 207 76 0 379 44 186 259 45 377 229 0 380 49 175 263 50 233 57 0 381 187 248 189 184 234 353 0 382 263 49 175 48 233 208 0 383 175 50 177 49 209 57 0 384 176 248 184 183 210 354 0 385 175 177 176 50 56 209 0 386 51 177 50 52 211 215 0 387 178 183 179 104 212 213 0 388 50 177 175 51 209 211 0 389 104 183 178 105 213 63 0 390 177 179 176 181 214 59 0 391 104 178 103 183 58 213 0 392 181 52 53 177 61 219 0 393 180 178 169 103 216 217 0 394 177 52 181 51 219 215 0 395 103 178 180 104 217 58 0 396 179 181 158 177 222 59 0 397 103 180 102 178 60 217 0 398 53 181 52 54 61 174 0 399 178 169 180 182 216 62 0 400 181 177 52 179 219 59 0 401 102 180 101 103 221 60 0 402 181 158 179 152 222 29 0 403 169 180 178 172 216 52 0 404 105 249 183 106 223 69 0 405 176 177 179 175 214 56 0 406 105 183 104 249 63 223 0 407 183 249 189 105 225 223 0 408 175 176 184 177 226 56 0 409 183 189 248 249 64 225 0 410 253 111 112 110 96 244 0 411 186 265 254 188 232 367 0 412 253 109 110 249 231 65 0 413 263 47 48 46 55 68 0 414 187 185 194 189 207 67 0 415 186 263 188 45 66 206 0 416 109 249 108 253 227 65 0 417 186 188 265 263 367 66 0 418 189 185 187 253 67 364 0 419 263 48 49 47 208 55 0 420 189 187 248 185 234 67 0 421 263 175 188 49 386 233 0 422 249 253 189 109 356 65 0 423 188 175 184 263 384 386 0 424 249 108 109 107 227 235 0 425 35 258 190 36 237 2 0 426 259 247 42 191 238 352 0 427 193 190 264 143 365 240 0 428 259 44 186 43 377 54 0 429 252 194 208 192 362 74 0 430 259 43 44 42 54 239 0 431 208 185 256 194 371 76 0 432 193 254 174 264 366 388 0 433 112 256 253 113 241 274 0 434 254 259 186 191 242 73 0 435 194 192 174 252 243 74 0 436 112 253 111 256 96 241 0 437 193 174 192 254 245 366 0 438 256 253 112 185 241 363 0 439 12 195 211 13 77 256 0 440 223 224 222 198 114 83 0

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203 441 195 211 12 216 77 108 0 442 196 120 240 121 335 135 0 443 237 244 242 233 342 133 0 444 121 196 122 120 78 135 0 445 141 221 142 227 250 296 0 446 222 241 242 224 251 350 0 447 142 221 246 141 79 250 0 448 199 125 124 126 306 81 0 449 202 127 126 128 262 360 0 450 126 199 250 125 258 81 0 451 126 250 202 199 252 258 0 452 223 198 224 200 83 255 0 453 255 250 195 202 85 82 0 454 195 14 255 13 260 254 0 455 201 198 124 224 247 302 0 456 195 13 14 12 254 256 0 457 198 124 201 199 247 253 0 458 216 250 200 195 259 358 0 459 124 199 125 198 306 253 0 460 255 203 251 15 84 87 0 461 195 255 250 14 85 260 0 462 126 202 127 250 262 252 0 463 116 203 117 115 263 261 0 464 16 203 15 204 264 90 0 465 117 203 204 116 265 263 0 466 118 204 119 117 89 88 0 467 203 204 117 16 265 90 0 468 17 204 16 205 266 91 0 469 16 204 203 17 90 266 0 470 18 205 17 238 268 134 0 471 205 239 240 238 269 334 0 472 17 205 204 18 91 268 0 473 29 212 220 30 270 102 0 474 216 223 206 200 271 115 0 475 220 210 206 212 92 298 0 476 34 190 207 35 272 144 0 477 252 262 215 260 273 379 0 478 34 207 33 190 93 272 0 479 208 194 185 252 76 362 0 480 261 5 6 257 101 276 0 481 192 215 143 252 145 361 0 482 261 257 5 260 276 288 0 483 207 143 214 190 277 5 0 484 261 260 257 209 288 378 0 485 30 214 212 31 278 104 0 486 211 216 210 195 279 108 0 487 30 212 29 214 102 278 0 488 213 10 11 209 304 105 0 489 210 212 211 220 281 298 0 490 10 209 9 213 290 105 0 491 31 207 214 32 282 106 0 492 213 211 212 11 283 103 0 493 31 214 30 207 104 282 0 494 213 209 10 262 105 383 0 495 212 214 213 30 285 278 0 496 9 209 8 10 280 290 0 497 33 207 32 34 286 93 0 498 215 213 214 262 287 107 0 499 32 207 31 33 106 286 0 500 209 8 9 261 280 381 0 501 214 207 143 31 277 282 0 502 8 261 7 209 284 381 0 503 211 11 12 213 246 103 0 504 206 210 216 220 291 92 0 505 11 213 10 211 304 103 0 506 25 217 24 229 292 316 0 507 217 133 132 134 293 132 0 508 24 217 234 25 109 292 0 509 28 220 218 29 294 112 0 510 219 228 220 227 295 314 0 511 28 218 27 220 110 294 0

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204 512 140 227 141 139 111 122 0 513 218 220 228 28 297 294 0 514 227 141 140 221 111 296 0 515 220 212 210 29 298 270 0 516 221 219 206 227 299 113 0 517 29 220 28 212 112 270 0 518 221 206 197 219 300 299 0 519 222 224 241 223 350 114 0 520 221 227 219 141 113 296 0 521 201 224 198 245 302 116 0 522 220 206 219 210 303 92 0 523 200 216 250 223 259 115 0 524 216 195 250 211 358 108 0 525 222 206 223 197 305 301 0 526 12 211 11 195 246 77 0 527 201 123 122 124 338 345 0 528 197 221 206 246 300 349 0 529 201 124 123 198 345 247 0 530 27 225 26 218 307 313 0 531 226 136 229 137 125 119 0 532 26 225 229 27 117 307 0 533 137 226 138 136 310 119 0 534 226 228 138 225 121 312 0 535 228 138 226 139 121 309 0 536 139 228 227 138 311 309 0 537 225 228 226 218 312 123 0 538 139 227 140 228 122 311 0 539 27 218 225 28 313 110 0 540 219 227 228 221 314 113 0 541 225 218 228 27 123 313 0 542 134 217 229 133 315 132 0 543 25 229 217 26 316 120 0 544 134 229 135 217 124 315 0 545 20 230 19 231 317 127 0 546 237 239 230 243 318 249 0 547 19 230 238 20 333 317 0 548 21 231 20 22 319 321 0 549 231 233 237 232 320 322 0 550 20 231 230 21 127 319 0 551 22 232 231 23 128 325 0 552 233 237 231 244 320 133 0 553 231 22 232 21 128 321 0 554 244 236 246 233 129 343 0 555 232 234 233 23 324 130 0 556 236 131 130 235 140 330 0 557 23 234 232 24 130 327 0 558 235 233 234 236 326 328 0 559 232 23 234 22 130 325 0 560 234 217 235 24 131 109 0 561 236 233 235 244 328 343 0 562 234 24 217 23 109 327 0 563 235 131 236 132 330 323 0 564 235 217 132 234 329 131 0 565 132 217 133 235 293 329 0 566 196 239 243 240 331 248 0 567 230 231 237 20 332 127 0 568 233 244 237 236 133 343 0 569 238 19 230 18 333 126 0 570 239 240 205 196 269 248 0 571 18 238 205 19 134 126 0 572 120 240 196 119 335 136 0 573 238 230 239 19 336 333 0 574 196 240 239 120 248 335 0 575 119 204 240 118 267 89 0 576 204 205 240 17 337 91 0 577 119 240 120 204 136 267 0 578 245 243 241 196 137 139 0 579 242 246 197 244 143 138 0 580 245 122 196 201 341 141 0 581 244 246 242 236 138 129 0 582 241 243 237 245 344 137 0

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205 583 246 130 129 236 142 339 0 584 122 196 245 121 341 78 0 585 244 242 237 246 342 138 0 586 245 196 243 122 139 341 0 587 236 246 244 130 129 339 0 588 243 196 239 245 331 139 0 589 130 236 131 246 140 339 0 590 245 201 122 224 141 116 0 591 242 197 222 246 346 143 0 592 122 201 123 245 338 141 0 593 142 246 129 221 347 79 0 594 245 241 224 243 348 137 0 595 129 246 130 142 142 347 0 596 246 221 197 142 349 79 0 597 224 245 241 201 348 116 0 598 246 197 242 221 143 349 0 599 39 247 38 40 351 4 0 600 191 247 259 258 352 375 0 601 38 247 258 39 374 351 0 602 184 248 187 176 353 210 0 603 183 248 176 189 354 64 0 604 189 248 183 187 64 234 0 605 107 249 106 108 355 235 0 606 189 249 253 183 356 225 0 607 106 249 105 107 69 355 0 608 200 250 199 216 357 259 0 609 195 250 216 255 358 85 0 610 202 250 255 126 82 252 0 611 128 251 115 202 359 80 0 612 202 251 128 255 80 369 0 613 115 251 203 128 86 359 0 614 192 252 215 194 361 74 0 615 208 252 194 260 362 94 0 616 260 262 252 209 379 382 0 617 185 253 256 189 363 364 0 618 189 253 185 249 364 356 0 619 110 253 109 111 231 244 0 620 254 264 191 193 75 388 0 621 174 254 265 193 390 366 0 622 191 254 264 259 75 73 0 623 186 254 259 265 242 232 0 624 15 255 14 203 368 87 0 625 202 255 251 250 369 82 0 626 14 255 195 15 260 368 0 627 208 256 257 185 370 371 0 628 185 256 208 253 371 363 0 629 113 256 112 114 274 98 0 630 5 257 4 261 372 276 0 631 208 257 260 256 373 370 0 632 4 257 3 5 275 372 0 633 247 258 38 191 374 375 0 634 191 258 247 264 375 387 0 635 37 258 36 38 1 3 0 636 42 259 247 43 238 239 0 637 186 259 44 254 377 242 0 638 191 259 254 247 73 352 0 639 209 260 261 262 378 382 0 640 252 260 262 208 379 94 0 641 208 260 252 257 94 373 0 642 7 261 6 8 380 284 0 643 209 261 8 260 381 378 0 644 6 261 5 7 101 380 0 645 209 262 260 213 382 383 0 646 213 262 209 215 383 107 0 647 215 262 213 252 107 273 0 648 46 263 45 47 385 68 0 649 188 263 175 186 386 66 0 650 45 263 186 46 206 385 0 651 191 264 258 254 387 75 0 652 193 264 254 190 388 365 0 653 190 264 193 258 365 70 0

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206 654 174 265 187 254 389 390 0 655 254 265 174 186 390 232 0 656 188 265 186 184 367 236 0 1 36 37 258 2 35 36 258 3 37 38 258 4 39 40 247 5 190 143 207 6 61 62 63 7 61 63 144 8 60 61 144 9 63 64 144 10 64 65 144 11 59 60 146 12 144 65 145 13 65 66 145 14 144 146 60 15 66 67 145 16 67 68 147 17 146 149 59 18 150 148 147 19 69 70 150 20 57 58 149 21 153 151 150 22 71 72 153 23 56 57 152 24 153 72 156 25 73 74 156 26 152 155 158 27 74 75 156 28 76 77 157 29 152 158 181 30 173 163 159 31 88 89 160 32 166 88 160 33 89 90 160 34 161 160 90 35 95 161 93 36 91 92 161 37 92 93 161 38 93 94 95 39 90 91 161 40 96 165 161 41 87 88 166 42 98 172 162 43 166 163 85 44 164 163 166 45 97 162 165 46 86 87 166 47 167 158 155 48 77 78 168 49 172 100 180 50 81 82 170 51 171 170 173 52 172 180 169 53 163 173 83 54 43 44 259 55 47 48 263 56 175 177 176 57 49 50 175 58 103 104 178 59 177 181 179 60 102 103 180 61 52 53 181 62 182 169 178 63 104 105 183 64 183 189 248 65 253 249 109 66 186 263 188 67 187 189 185

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207 68 46 47 263 69 105 106 249 70 258 264 190 71 40 41 247 72 193 192 143 73 254 191 259 74 252 192 194 75 254 264 191 76 185 208 194 77 12 195 211 78 121 196 122 79 142 221 246 80 128 202 251 81 125 199 126 82 255 202 250 83 198 224 223 84 251 255 203 85 255 250 195 86 115 251 203 87 15 203 255 88 117 204 118 89 118 204 119 90 16 204 203 91 17 205 204 92 220 210 206 93 33 34 207 94 208 260 252 95 2 3 257 96 111 112 253 97 2 257 256 98 113 114 256 99 256 114 2 100 1 2 114 101 5 6 261 102 29 30 212 103 213 11 211 104 30 31 214 105 213 209 10 106 31 32 207 107 215 262 213 108 195 216 211 109 24 217 234 110 27 28 218 111 140 227 141 112 28 29 220 113 221 227 219 114 223 224 222 115 200 223 216 116 201 245 224 117 225 229 26 118 135 229 136 119 136 226 137 120 25 26 229 121 226 228 138 122 139 227 140 123 228 225 218 124 134 229 135 125 229 226 136 126 18 19 238 127 20 231 230 128 232 231 22 129 244 236 246 130 232 23 234 131 235 234 217 132 133 217 134 133 237 233 244 134 238 205 18 135 120 196 121 136 119 240 120 137 245 243 241 138 242 244 246

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208 139 245 196 243 140 130 236 131 141 245 201 122 142 129 246 130 143 242 246 197 144 34 35 190 145 143 192 215 146 58 59 149 147 67 147 145 148 68 69 147 149 145 146 144 150 149 152 57 151 147 148 145 152 69 150 147 153 145 148 146 154 150 71 153 155 148 149 146 156 55 56 152 157 150 151 148 158 70 71 150 159 148 151 149 160 156 154 153 161 151 152 149 162 152 181 55 163 153 154 151 164 72 73 156 165 152 151 155 166 156 75 157 167 151 154 155 168 54 55 181 169 156 157 154 170 75 76 157 171 155 154 167 172 77 168 157 173 154 157 167 174 53 54 181 175 167 182 158 176 170 82 173 177 173 159 171 178 85 86 166 179 166 160 164 180 96 97 165 181 95 96 161 182 98 99 172 183 162 159 164 184 82 83 173 185 159 163 164 186 83 84 163 187 165 162 164 188 97 98 162 189 165 164 160 190 84 85 163 191 161 165 160 192 167 157 168 193 182 171 169 194 78 170 168 195 171 182 167 196 100 101 180 197 168 171 167 198 78 79 170 199 168 170 171 200 79 80 170 201 159 172 169 202 99 100 172 203 162 172 159 204 80 81 170 205 159 169 171 206 186 45 263 207 187 185 194 208 48 49 263 209 175 50 177

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209 210 184 176 248 211 50 51 177 212 179 178 183 213 178 104 183 214 179 176 177 215 51 52 177 216 180 178 169 217 180 103 178 218 179 182 178 219 181 177 52 220 182 179 158 221 101 102 180 222 158 179 181 223 105 249 183 224 183 176 179 225 183 249 189 226 184 175 176 227 108 109 249 228 187 194 174 229 44 45 186 230 184 187 265 231 109 110 253 232 186 265 254 233 49 175 263 234 187 248 189 235 107 108 249 236 265 188 184 237 258 190 35 238 247 42 259 239 42 43 259 240 190 193 143 241 112 256 253 242 254 259 186 243 194 192 174 244 110 111 253 245 193 174 192 246 11 12 211 247 201 198 124 248 196 240 239 249 239 237 243 250 141 221 142 251 242 222 241 252 126 250 202 253 199 124 198 254 13 14 195 255 200 198 223 256 12 13 195 257 199 198 200 258 250 126 199 259 216 250 200 260 195 14 255 261 115 203 116 262 126 202 127 263 116 203 117 264 15 16 203 265 204 117 203 266 16 17 204 267 240 119 204 268 17 18 205 269 240 205 239 270 29 212 220 271 216 223 206 272 207 34 190 273 215 252 262 274 112 113 256 275 3 4 257 276 261 257 5 277 143 214 207 278 30 214 212 279 211 216 210 280 8 9 209

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210 281 211 210 212 282 31 207 214 283 212 213 211 284 7 8 261 285 213 212 214 286 32 33 207 287 214 215 213 288 257 261 260 289 143 215 214 290 9 10 209 291 216 206 210 292 24 25 217 293 132 217 133 294 28 220 218 295 220 219 228 296 141 227 221 297 220 228 218 298 220 212 210 299 206 221 219 300 206 197 221 301 206 222 197 302 198 201 224 303 220 206 219 304 10 11 213 305 223 222 206 306 124 199 125 307 26 27 225 308 225 226 229 309 138 228 139 310 137 226 138 311 228 227 139 312 226 225 228 313 27 218 225 314 228 219 227 315 229 134 217 316 229 217 25 317 19 20 230 318 237 239 230 319 20 21 231 320 237 231 233 321 21 22 231 322 232 233 231 323 131 235 132 324 233 232 234 325 22 23 232 326 234 235 233 327 23 24 234 328 236 233 235 329 132 235 217 330 236 235 131 331 239 243 196 332 237 230 231 333 19 230 238 334 238 239 205 335 196 120 240 336 239 238 230 337 240 204 205 338 122 201 123 339 246 236 130 340 242 241 237 341 245 122 196 342 237 244 242 343 244 233 236 344 237 241 243 345 123 201 124 346 222 242 197 347 142 246 129 348 241 224 245 349 197 246 221 350 241 222 224 351 38 39 247

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211 352 259 191 247 353 184 248 187 354 183 248 176 355 106 107 249 356 249 253 189 357 250 199 200 358 216 195 250 359 128 251 115 360 127 202 128 361 215 192 252 362 252 194 208 363 256 185 253 364 189 253 185 365 193 190 264 366 193 254 174 367 186 188 265 368 14 15 255 369 255 251 202 370 256 257 208 371 208 185 256 372 4 5 257 373 257 260 208 374 258 38 247 375 191 258 247 376 41 42 247 377 44 186 259 378 261 209 260 379 252 260 262 380 6 7 261 381 209 261 8 382 260 209 262 383 213 262 209 384 184 188 175 385 45 46 263 386 263 175 188 387 258 191 264 388 193 264 254 389 174 265 187 390 174 254 265

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APPENDIX E DSSAT MODIFICATIONS

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213 Changes needed in GROSUB to account for plants growing on BedWidth (cm), but with LAI draping over the entire row spacing (RowSP, in cm) James W. Jones 8-18-02 1. Potato plants are grown as individua l plants in GROSUB. The variable PLANTS is the number of plants per meter square. Thus, daily growth is computed by dividing overall growth per m2 by the plant population. LAI is computed by multiplying the area per plant (PLA, m2[leaf area]/plant) by PLANT (plants/m2[soil area]). Getting biomass per m2[soil area] also requires multiplying biomass per plant by PLANTS to get g[biomass]/(m2[ground area]). 2. To account for plants growing only on the bed, it is best to assume that PLANTS is the plants per m2[bed area], and thus the row spacing and plant population put in fileX are on a bed basis, not a row width basis. This will allow one to compute all soil processes as they are, and just to convert biomass values to account for the differences in row width vs. bed width. This is done as follows: 3. LAI is computed by multiplying LAI computed on a bed basis (now that this is the basic dimension of the model) by the ratio of Bed Width to Rowspacing (or, by BedWidth/RowSP). Since these variables are not in the model input file yet, I suggest that the numbers be used instead ov variables, or that these variables are declared locally in GROSUB. For example, if BedWidth = 0.5 and RowSP = 0.9, then the ratio would be 0.5/0.9. This LAI computation needs to be done in several places. 4. Daily growth (PCARB, g/(plant) per day), accounts for PLANTS, the plants per m2 row width, but since LAI has already been adjusted (downward since BedWidth is less than RowSP), then growth is computed on a per m2[row width] basis and this must be adjusted upward. This is done by multiplying PCARB by the ratio (RowSP / BedWidth). 5. Finally, biomass in g per m2[bed] is computed by multiplying per plant values by PLANTS (RowSP / BedWidth). 6. The resulting biomass values that are output will thus be for the BED WIDTH, not the entire row width, but LAI will come out as leaf area on a row width basis NOT bed width.

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214 GROSUB XLAI on Line 179 !*********************************************************************** !*********************************************************************** Daily rate calculations !*********************************************************************** ELSEIF (DYNAMIC .EQ. RATE) THEN !----------------------------------------------------------------------IF (FIRST) THEN !Initializations from PHASEI, all Case(7), except where noted. FIRST = .FALSE. XLAI = PLA PLANTS 0.0001 XLAI = PLA PLANTS 0.0001 *BedWidth / RowSp LFWT = 0.093 Line 274 IF (DDEADLF .GE. LFWT) THEN DDEADLF = LFWT END IF ! Senescence calculation, end ! Update of haulm after senescence LFWT = LFWT DDEADLF PLA = LFWT LALWR XLAI = PLA PLANTS 0.0001 XLAI = PLA PLANTS 0.0001 BedWidth / RowSP TOPWT = LFWT + STMWT Line 290 PCARB IF (ISTAGE .LT. 2) THEN PCARB = 3.5*PAR/PLANTS*(1.0 EXP(-0.55*XLAI)) PCARB = 3.5*PAR/PLANTS*(1.0 EXP(-0.55*XLAI)) RowSP / BedWidth ELSE PCARB = 4.0*PAR/PLANTS*(1.0 EXP(-0.55*XLAI)) PCARB = 4.0*PAR/PLANTS*(1.0 EXP(-0.55*XLAI)) RowSP / BedWidth END IF

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215 Line 421 AND 423 in GROSUB ! Calculation of potential growth .. Set priorities for carbon ! PTUBGR = G3*ETGT/PLANTS PTUBGR = G3*ETGT/PLANTS (RowSP / BedWidth) GROTUB = PTUBGR*AMIN1 (TURFAC, AGEFAC, 1.0)*TIND PLAG = G2*DTT/PLANTS PLAG = G2*DTT/PLANTS (RowSP / BedWidth) PLAG = PLAG *AMIN1 (TURFAC, AGEFAC, 1.0) GROLF = PLAG/LALWR GROSTM = GROLF*0.75 RTPAR = 0.2 GRORT = (GROLF + GROSTM)* RTPAR GROPLNT = GROLF + GROSTM + GRORT RVCAV = RVCHO CARBO = CARBO + RVCAV Lines 531 in GROSUB IF (GROTOP .LT. 0.0) THEN DEADLF = DEADLF GROTOP*0.5 END IF PLAG = GROLF LALWR PLA = PLA + PLAG XLAI = PLA PLANTS 0.0001 XLAI = PLA PLANTS 0.0001 (BedSP / RowWidth) IF (TOPWT .LE. 0.0) THEN TOPWT = 0.0 XLAI = 0.0 TANC = 0.0 ELSE TANC = TOPSN/TOPWT END IF BIOMAS = (LFWT + STMWT + TUBWT)*PLANTS

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APPENDIX F MODIFIED DSSAT/SUBSTOR INPUT FILES

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217Modified North Half SUBSTOR Input File (2001) *MODEL INPUT FILE I 1 5 1 3 0 *FILES MODEL PTSUB980.EXE FILEX REDLASOD.PTX FILEA REDLASOD.PTA FILET REDLASOD.PTT SPECIES PTSUB980.SPE C:\DSSAT35\GENOTYPE\ ECOTYPE CULTIVAR PTSUB980.CUL C:\DSSAT35\GENOTYPE\ PESTS PTSUB980.PST C:\DSSAT35\PEST\ SOILS SOIL.SOL C:\DSSAT35\SOIL\ WEATHER UFSU0101.WTH C:\DSSAT35\WEATHER\ OUTPUT OVERVIEW *SIMULATION CONTROL 1 1 I 1001 2150 REDSODA1 Y Y N N N N N N M M E R R C R 1 U R R R N R N Y Y 1 Y N Y Y N Y Y N N !AUTOMATIC MANAGEM 1354 1354 40. 100. 30. 40. 10. 30. 50. 100. GS000 IR001 10.0 1.000 30. 50. 25. FE001 GS000 100. 1 20. 0 2354 100. 0. *EXP.DETAILS 5REDLASOD PT REDLASODPT *TREATMENTS 10 0 0 NORTHHALF *CULTIVARS PT UF0001 RED LASODA *FIELDS UFSW0001 UFSU0101 .0 0. DR000 0. 100. 00000 FSA 60. UF00850002 -83.04000 30.08000 13.70 99.0 995. 1.0 .0 *INITIAL CONDITIONS CO 01001 1. 0. 1.00 1.00 200.0 0 .00 .00 100. 15. 5. .084 3.2 5.3 15. .084 3.2 5.3 30. .094 3.2 5.3 45. .083 3.2 5.3 60. .083 3.1 2.5 90. .089 3.0 1.1 *PLANTING DETAILS 1046 1066 5.4 4.6 B R 90. 50.5 16.0 1500. -99. -99.0 -99.0 5.0

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218 *IRRIGATION .900 60. 50. 100. GS000 IR001 10.0 1007 IR004 5.0 0 1012 IR004 3.0 0 1013 IR004 5.0 0 1037 IR004 3.0 0 1043 IR004 7.0 0 1048 IR004 6.0 0 1051 IR004 5.0 0 1053 IR004 7.0 0 1055 IR004 9.0 0 1060 IR004 8.0 0 1066 IR004 4.0 0 1071 IR004 5.0 0 1083 IR004 9.0 0 1085 IR004 6.0 0 1091 IR004 8.0 0 1092 IR004 9.0 0 1093 IR004 8.0 0 1094 IR004 9.0 0 1095 IR004 8.0 0 1096 IR004 9.0 0 1097 IR004 8.0 0 1098 IR004 9.0 0 1099 IR004 8.0 0 1100 IR004 9.0 0 1101 IR004 8.0 0 1102 IR004 9.0 0 1103 IR004 8.0 0 1104 IR004 9.0 0 1105 IR004 8.0 0 1106 IR004 9.0 0 1107 IR004 8.0 0 1108 IR004 9.0 0 1109 IR004 8.0 0 1110 IR004 9.0 0 1111 IR004 8.0 0 1112 IR004 9.0 0 1113 IR004 8.0 0 1114 IR004 9.0 0 1115 IR004 8.0 0 1116 IR004 9.0 0 1117 IR004 8.0 0 1118 IR004 9.0 0 1119 IR004 8.0 0 1120 IR004 9.0 0

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219 1121 IR004 8.0 0 1122 IR004 9.0 0 1123 IR004 8.0 0 1124 IR004 9.0 0 1125 IR004 8.0 0 1126 IR004 9.0 0 1127 IR004 8.0 0 1128 IR004 9.0 0 1129 IR004 8.0 0 1130 IR004 9.0 0 1131 IR004 8.0 0 1132 IR004 9.0 0 1133 IR004 8.0 0 1134 IR004 9.0 0 1135 IR004 8.0 0 1136 IR004 9.0 0 1137 IR004 8.0 0 1138 IR004 9.0 0 1139 IR004 8.0 0 1140 IR004 9.0 0 *FERTILIZERS 1007 FE001 AP005 0. 1. 0. 0. 0. 0. 1012 FE001 AP005 0. 1. 0. 0. 0. 0. 1013 FE001 AP005 0. 1. 0. 0. 0. 0. 1018 FE001 AP009 15. 76. 0. 0. 0. 0. 1037 FE001 AP005 0. 1. 0. 0. 0. 0. 1043 FE001 AP005 0. 1. 0. 0. 0. 0. 1046 FE001 AP004 15. 34. 0. 0. 0. 0. 1048 FE001 AP005 0. 1. 0. 0. 0. 0. 1051 FE001 AP005 0. 1. 0. 0. 0. 0. 1053 FE001 AP005 0. 1. 0. 0. 0. 0. 1055 FE001 AP005 0. 2. 0. 0. 0. 0. 1060 FE001 AP005 0. 2. 0. 0. 0. 0. 1064 FE001 AP009 15. 224. 0. 0. 0. 0. 1066 FE001 AP005 0. 1. 0. 0. 0. 0. 1071 FE001 AP005 0. 1. 0. 0. 0. 0. 1083 FE001 AP005 0. 2. 0. 0. 0. 0. 1084 FE001 AP009 15. 224. 0. 0. 0. 0. 1091 FE001 AP005 0. 2. 0. 0. 0. 0. 1092 FE001 AP005 0. 2. 0. 0. 0. 0. 1093 FE001 AP005 0. 2. 0. 0. 0. 0. 1094 FE001 AP005 0. 2. 0. 0. 0. 0. 1095 FE001 AP005 0. 2. 0. 0. 0. 0. 1096 FE001 AP005 0. 2. 0. 0. 0. 0. 1097 FE001 AP005 0. 2. 0. 0. 0. 0. 1098 FE001 AP005 0. 2. 0. 0. 0. 0. 1099 FE001 AP005 0. 2. 0. 0. 0. 0.

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220 1100 FE001 AP005 0. 2. 0. 0. 0. 0. 1101 FE001 AP005 0. 2. 0. 0. 0. 0. 1102 FE001 AP005 0. 2. 0. 0. 0. 0. 1103 FE001 AP005 0. 2. 0. 0. 0. 0. 1104 FE001 AP005 0. 2. 0. 0. 0. 0. 1105 FE001 AP005 0. 2. 0. 0. 0. 0. 1106 FE001 AP005 0. 2. 0. 0. 0. 0. 1107 FE001 AP005 0. 2. 0. 0. 0. 0. 1108 FE001 AP005 0. 2. 0. 0. 0. 0. 1109 FE001 AP005 0. 2. 0. 0. 0. 0. 1110 FE001 AP005 0. 2. 0. 0. 0. 0. 1111 FE001 AP005 0. 2. 0. 0. 0. 0. 1112 FE001 AP005 0. 2. 0. 0. 0. 0. 1113 FE001 AP004 0. 34. 0. 0. 0. 0. 1114 FE001 AP005 0. 2. 0 0 0 0 1115 FE001 AP005 0. 2. 0. 0. 0. 0. 1116 FE001 AP005 0. 2. 0 0 0 0 1117 FE001 AP005 0. 2. 0. 0. 0. 0. 1118 FE001 AP005 0. 2. 0 0 0 0 1119 FE001 AP005 0. 2. 0. 0. 0. 0. 1120 FE001 AP005 0. 2. 0 0 0 0 1121 FE001 AP005 0. 2. 0. 0. 0. 0. 1122 FE001 AP005 0. 2. 0 0 0 0 1123 FE001 AP005 0. 2. 0. 0. 0. 0. 1124 FE001 AP005 0. 2. 0 0 0 0 1125 FE001 AP005 0. 2. 0. 0. 0. 0. 1126 FE001 AP005 0. 2. 0 0 0 0 1127 FE001 AP005 0. 2. 0. 0. 0. 0. 1128 FE001 AP005 0. 2. 0 0 0 0 1129 FE001 AP005 0. 2. 0. 0. 0. 0. 1130 FE001 AP005 0. 2. 0 0 0 0 1131 FE001 AP005 0. 2. 0. 0. 0. 0. 1132 FE001 AP005 0. 2. 0 0 0 0 1133 FE001 AP005 0. 2. 0. 0. 0. 0. 1134 FE001 AP005 0. 2. 0 0 0 0 1135 FE001 AP005 0. 2. 0. 0. 0. 0. 1136 FE001 AP005 0. 2. 0 0 0 0 1137 FE001 AP005 0. 2. 0. 0. 0. 0. 1138 FE001 AP005 0. 2. 0 0 0 0 1139 FE001 AP005 0. 2. 0. 0. 0. 0. 1140 FE001 AP005 0. 2. 0 0 0 0 *RESIDUES *CHEMICALS *TILLAGE *ENVIRONMENT *HARVEST 1141 GS000 L A 100. 0.

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221*SOIL UF00850002 SCS FSA 60. TEMPLATE TEMPLATE USA -82.000 24.000 00 GROSSARENIC PALEUDULTS G .13 5.6 .50 95. 1.00 1.00 IB001 IB001 IB001 5. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 15. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 30. .017 .097 .388 .500 188.0 1.48 .02 1.2 3.7 1.1 -9.00 5.3 4.8 4.0 .0 45. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 60. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 90. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 5. .0 .0 .0 .0 .0 .0 .0 .0 15. .0 .0 .0 .0 .0 .0 .0 .0 30. .0 .0 .0 .0 .0 .0 .0 .0 45. .0 .0 .0 .0 .0 .0 .0 .0 60. .0 .0 .0 .0 .0 .0 .0 .0 90. .0 .0 .0 .0 .0 .0 .0 .0 *CULTIVAR UF0001 RED LASODA IB0001 2000. 22.0 .20 .7 .4 19.0 Modified North Half SUBSTOR Input File (2002) *MODEL INPUT FILE I 1 4 1 2 0 *FILES MODEL PTSUB980.EXE FILEX RDLASD02.PTX FILEA RDLASD02.PTA FILET RDLASD02.PTT SPECIES PTSUB980.SPE C:\DSSAT35\GENOTYPE\ ECOTYPE CULTIVAR PTSUB980.CUL C:\DSSAT35\GENOTYPE\ PESTS PTSUB980.PST C:\DSSAT35\PEST\ SOILS SOIL.SOL C:\DSSAT35\SOIL\ WEATHER UFSU0201.WTH C:\DSSAT35\WEATHER\ OUTPUT OVERVIEW *SIMULATION CONTROL 1 1 I 2009 2150 REDSODA1 Y Y N N N N N N M M E R R C R 1 U R R R N R N Y Y 1 Y N Y Y N Y Y N N !AUTOMATIC MANAGEM 1354 1354 40. 100. 30. 40. 10. 30. 50. 100. GS000 IR001 10.0 1.000 30. 50. 25. FE001 GS000 100. 1 20.

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222 0 2354 100. 0. *EXP.DETAILS 4RDLASD02 PT RDLASD02PT *TREATMENTS 10 0 0 NORTHHALF *CULTIVARS PT UF0001 RED LASODA *FIELDS UFSW0001 UFSU0201 .0 0. DR000 0. 100. 00000 FSA 60. UF00850002 -83.04000 30.08000 13.70 99.0 995. 1.0 .0 *INITIAL CONDITIONS MZ 2009 1. 0. 1.00 1.00 200.0 0 .00 .00 100. 15. 5. .081 5.6 4.0 15. .081 5.6 4.0 30. .082 3.6 3.2 45. .086 3.6 2.7 60. .086 3.6 2.7 90. .081 3.2 2.1 *PLANTING DETAILS 2043 2069 5.4 4.6 B R 90. 45. 16.0 1500. -99. -99.0 -99.0 5.0 *IRRIGATION .900 60. 50. 100. GS000 IR001 10.0 2059 IR004 6.0 0 2073 IR004 8.0 0 2075 IR004 7.0 0 2078 IR004 9.0 0 2082 IR004 9.0 0 2083 IR004 9.0 0 2084 IR004 5.0 0 2085 IR004 9.0 0 2086 IR004 9.0 0 2087 IR004 9.0 0 2088 IR004 9.0 0 2089 IR004 9.0 0 2090 IR004 9.0 0 2091 IR004 9.0 0 2094 IR004 10.0 0 2095 IR004 9.0 0 2096 IR004 9.0 0 2097 IR004 9.0 0 2098 IR004 9.0 0 2099 IR004 9.0 0 2105 IR004 9.0 0 2106 IR004 7.0 0 2107 IR004 9.0 0 2108 IR004 5.0 0 2109 IR004 7.0 0

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223 2110 IR004 7.0 0 2111 IR004 7.0 0 2112 IR004 7.0 0 2113 IR004 9.0 0 2114 IR004 9.0 0 2115 IR004 9.0 0 2116 IR004 8.0 0 2117 IR004 8.0 0 2118 IR004 8.0 0 2119 IR004 8.0 0 2120 IR004 8.0 0 2121 IR004 8.0 0 2122 IR004 8.0 0 2123 IR004 7.0 0 2126 IR004 6.0 0 2127 IR004 6.0 0 2129 IR004 4.0 0 2130 IR004 4.0 0 2131 IR004 4.0 0 *FERTILIZERS 2010 FE001 AP004 15 82 0 0 0 0 2015 FE001 AP004 15 57 0 0 0 0 2044 FE001 AP004 15 34 0 0 0 0 2059 FE001 AP005 0 1. 0 0 0 0 2072 FE001 AP004 15 203 0 0 0 0 2073 FE001 AP005 0 2. 0 0 0 0 2075 FE001 AP005 0 1. 0 0 0 0 2078 FE001 AP005 0 2. 0 0 0 0 2082 FE001 AP005 0 2. 0 0 0 0 2083 FE001 AP005 0 2. 0 0 0 0 2084 FE001 AP004 15 208 0 0 0 0 2085 FE001 AP005 0 2. 0 0 0 0 2086 FE001 AP005 0 2. 0 0 0 0 2087 FE001 AP005 0 2. 0 0 0 0 2088 FE001 AP005 0 2. 0 0 0 0 2089 FE001 AP005 0 2. 0 0 0 0 2090 FE001 AP005 0 2. 0 0 0 0 2091 FE001 AP005 0 2. 0 0 0 0 2094 FE001 AP005 0 2. 0 0 0 0 2095 FE001 AP005 0 2. 0 0 0 0 2096 FE001 AP005 0 2. 0 0 0 0 2097 FE001 AP005 0 2. 0 0 0 0 2098 FE001 AP005 0 2. 0 0 0 0 2099 FE001 AP005 0 2. 0 0 0 0 2105 FE001 AP005 0 2. 0 0 0 0 2106 FE001 AP005 0 1. 0 0 0 0 2107 FE001 AP005 0 2. 0 0 0 0

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224 2108 FE001 AP005 0 1. 0 0 0 0 2109 FE001 AP005 0 1. 0 0 0 0 2110 FE001 AP005 0 1. 0 0 0 0 2111 FE001 AP005 0 1. 0 0 0 0 2112 FE001 AP005 0 1. 0 0 0 0 2113 FE001 AP005 0 2. 0 0 0 0 2114 FE001 AP005 0 2. 0 0 0 0 2115 FE001 AP005 0 2. 0 0 0 0 2116 FE001 AP005 0 2. 0 0 0 0 2117 FE001 AP005 0 2. 0 0 0 0 2118 FE001 AP005 0 2. 0 0 0 0 2119 FE001 AP005 0 2. 0 0 0 0 2120 FE001 AP005 0 2. 0 0 0 0 2121 FE001 AP005 0 2. 0 0 0 0 2122 FE001 AP005 0 1. 0 0 0 0 2123 FE001 AP005 0 1. 0 0 0 0 2126 FE001 AP005 0 1. 0 0 0 0 2127 FE001 AP005 0 1. 0 0 0 0 2129 FE001 AP005 0 1. 0 0 0 0 2130 FE001 AP005 0 1. 0 0 0 0 2131 FE001 AP005 0 1. 0 0 0 0 *RESIDUES *CHEMICALS *TILLAGE *ENVIRONMENT *HARVEST 2138 GS000 L A 100. 0. *SOIL UF00850002 SCS FSA 60. TEMPLATE TEMPLATE USA -82.000 24.000 00 GROSSARENIC PALEUDULTS G .13 5.6 .50 95. 1.00 1.00 IB001 IB001 IB001 5. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 15. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 30. .017 .097 .388 .500 188.0 1.48 .02 1.2 3.7 1.1 -9.00 5.3 4.8 4.0 .0 45. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 60. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 90. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 5. .0 .0 .0 .0 .0 .0 .0 .0 15. .0 .0 .0 .0 .0 .0 .0 .0 30. .0 .0 .0 .0 .0 .0 .0 .0 45. .0 .0 .0 .0 .0 .0 .0 .0 60. .0 .0 .0 .0 .0 .0 .0 .0 90. .0 .0 .0 .0 .0 .0 .0 .0 *CULTIVAR UF0001 RED LASODA IB0001 2000. 22.0 .20 .7 .4 19.0

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225Modified South Half SUBSTOR Input File (2002) *MODEL INPUT FILE I 1 4 2 7 0 *FILES MODEL PTSUB980.EXE FILEX RDLASD02.PTX FILEA RDLASD02.PTA FILET RDLASD02.PTT SPECIES PTSUB980.SPE C:\DSSAT35\GENOTYPE\ ECOTYPE CULTIVAR PTSUB980.CUL C:\DSSAT35\GENOTYPE\ PESTS PTSUB980.PST C:\DSSAT35\PEST\ SOILS SOIL.SOL C:\DSSAT35\SOIL\ WEATHER UFSU0201.WTH C:\DSSAT35\WEATHER\ OUTPUT OVERVIEW *SIMULATION CONTROL 1 1 I 2009 2150 REDSODA1 Y Y N N N N N N M M E R R C R 1 U R R R N R N Y Y 1 Y N Y Y N Y Y N N !AUTOMATIC MANAGEM 1354 1354 40. 100. 30. 40. 10. 30. 50. 100. GS000 IR001 10.0 1.000 30. 50. 25. FE001 GS000 100. 1 20. 0 2354 100. 0. *EXP.DETAILS 4RDLASD02 PT RDLASD02PT *TREATMENTS 20 0 0 SOUTHHALF *CULTIVARS PT UF0001 RED LASODA *FIELDS UFSW0001 UFSU0201 .0 0. DR000 0. 100. 00000 FSA 60. UF00850002 -83.04000 30.08000 13.70 99.0 995. 1.0 .0 *INITIAL CONDITIONS MZ 2009 1. 0. 1.00 1.00 200.0 0 .00 .00 100. 15. 5. .081 5.6 4.0 15. .081 5.6 4.0 30. .082 3.6 3.2 45. .086 3.6 2.7 60. .086 3.6 2.7 90. .081 3.2 2.1 *PLANTING DETAILS 2046 2071 5.4 4.6 B R 90. 45. 16.0 1500. -99. -99.0 -99.0 5.0

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226*IRRIGATION .900 60. 50. 100. GS000 IR001 10.0 2059 IR004 6.0 0 2073 IR004 8.0 0 2075 IR004 7.0 0 2078 IR004 9.0 0 2082 IR004 4.0 0 2083 IR004 4.0 0 2084 IR004 5.0 0 2085 IR004 4.0 0 2086 IR004 4.0 0 2087 IR004 4.0 0 2088 IR004 4.0 0 2089 IR004 4.0 0 2090 IR004 5.0 0 2091 IR004 5.0 0 2094 IR004 6.0 0 2095 IR004 7.0 0 2096 IR004 7.0 0 2097 IR004 7.0 0 2098 IR004 6.0 0 2099 IR004 7.0 0 2106 IR004 7.0 0 2107 IR004 7.0 0 2108 IR004 5.0 0 2109 IR004 7.0 0 2110 IR004 7.0 0 2111 IR004 7.0 0 2112 IR004 7.0 0 2113 IR004 9.0 0 2114 IR004 9.0 0 2115 IR004 9.0 0 2116 IR004 8.0 0 2117 IR004 8.0 0 2118 IR004 8.0 0 2119 IR004 8.0 0 2120 IR004 8.0 0 2121 IR004 8.0 0 2122 IR004 8.0 0 2123 IR004 7.0 0 2125 IR004 5.0 0 2127 IR004 5.0 0 2129 IR004 4.0 0 2130 IR004 4.0 0 2131 IR004 4.0 0 *FERTILIZERS 2016 FE001 AP004 15. 181. 0. 0. 0. 0.

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227 2047 FE001 AP004 15. 34. 0. 0. 0. 0. 2059 FE001 AP005 0. 1. 0. 0. 0. 0. 2073 FE001 AP005 0. 2. 0. 0. 0. 0. 2074 FE001 AP004 15. 112. 0. 0. 0. 0. 2075 FE001 AP005 0. 1. 0. 0. 0. 0. 2078 FE001 AP005 0. 2. 0. 0. 0. 0. 2082 FE001 AP005 0. 1. 0. 0. 0. 0. 2083 FE001 AP005 0. 1. 0. 0. 0. 0. 2084 FE001 AP005 0. 1. 0. 0. 0. 0. 2085 FE001 AP004 15. 195. 0. 0. 0. 0. 2086 FE001 AP005 0. 1. 0. 0. 0. 0. 2087 FE001 AP005 0. 1. 0. 0. 0. 0. 2088 FE001 AP005 0. 1. 0. 0. 0. 0. 2089 FE001 AP005 0. 1. 0. 0. 0. 0. 2090 FE001 AP005 0. 1. 0. 0. 0. 0. 2091 FE001 AP005 0. 1. 0. 0. 0. 0. 2094 FE001 AP005 0. 1. 0. 0. 0. 0. 2095 FE001 AP005 0. 1. 0. 0. 0. 0. 2096 FE001 AP005 0. 1. 0. 0. 0. 0. 2097 FE001 AP005 0. 1. 0. 0. 0. 0. 2098 FE001 AP005 0. 1. 0. 0. 0. 0. 2099 FE001 AP005 0. 1. 0. 0. 0. 0. 2106 FE001 AP005 0. 1. 0. 0. 0. 0. 2107 FE001 AP005 0. 1. 0. 0. 0. 0. 2108 FE001 AP005 0. 1. 0. 0. 0. 0. 2109 FE001 AP005 0. 1. 0. 0. 0. 0. 2110 FE001 AP005 0. 1. 0. 0. 0. 0. 2111 FE001 AP005 0. 1. 0. 0. 0. 0. 2112 FE001 AP005 0. 1. 0. 0. 0. 0. 2113 FE001 AP005 0. 2. 0. 0. 0. 0. 2114 FE001 AP005 0. 2. 0. 0. 0. 0. 2115 FE001 AP005 0. 2. 0. 0. 0. 0. 2116 FE001 AP005 0. 2. 0. 0. 0. 0. 2117 FE001 AP005 0. 2. 0. 0. 0. 0. 2118 FE001 AP005 0. 2. 0. 0. 0. 0. 2119 FE001 AP005 0. 2. 0. 0. 0. 0. 2120 FE001 AP005 0. 2. 0. 0. 0. 0. 2121 FE001 AP005 0. 2. 0. 0. 0. 0. 2122 FE001 AP005 0. 2. 0. 0. 0. 0. 2123 FE001 AP005 0. 1. 0. 0. 0. 0. 2125 FE001 AP005 0. 1. 0. 0. 0. 0. 2127 FE001 AP005 0. 1. 0. 0. 0. 0. 2129 FE001 AP005 0. 1. 0. 0. 0. 0. 2130 FE001 AP005 0. 1. 0. 0. 0. 0. 2131 FE001 AP005 0. 1. 0. 0. 0. 0. *RESIDUES *CHEMICALS

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228*TILLAGE *ENVIRONMENT *HARVEST 2138 GS000 L A 100. 0. *SOIL UF00850002 SCS FSA 60. TEMPLATE TEMPLATE USA -82.000 24.000 00 GROSSARENIC PALEUDULTS G .13 5.6 .50 95. 1.00 1.00 IB001 IB001 IB001 5. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 15. .017 .097 .388 .750 188.0 1.48 .90 1.7 2.5 1.4 -9.00 5.2 4.3 4.0 .0 30. .017 .097 .388 .500 188.0 1.48 .02 1.2 3.7 1.1 -9.00 5.3 4.8 4.0 .0 45. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 60. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 90. .019 .080 .388 .150 156.6 1.56 .01 1.0 3.9 1.4 -9.00 5.3 4.8 4.0 .0 5. .0 .0 .0 .0 .0 .0 .0 .0 15. .0 .0 .0 .0 .0 .0 .0 .0 30. .0 .0 .0 .0 .0 .0 .0 .0 45. .0 .0 .0 .0 .0 .0 .0 .0 60. .0 .0 .0 .0 .0 .0 .0 .0 90. .0 .0 .0 .0 .0 .0 .0 .0 *CULTIVAR UF0001 RED LASODA IB0001 2000. 22.0 .20 .7 .4 19.0

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229 LIST OF REFERENCES Albert, M.A. (2002). Monitoring and Modeling the Fate and Transport of Nitrate in the Vadose Zone Beneath a Suwannee River Basin Vegetable Farm. Thesis, Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL. Allen, R.G., L.S. Perira, D. Raes, and M. Smith (1998). Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper 56. Rome, Italy. Belanger, G, J.R. Walsh, J.E. Richards, P.H. Milburn, and N. Ziadi (2000). Yield Response of Two Potato Cultivars to Supplemental Irrigation and N Fertilization in New Brunswick. American Journal of Potato Research 77:11-21. Brady, N.C. and R.R. Weil (2002). Nature and Properties of Soils 13th Ed. Prentice Hall, Inc.: Upper Saddle River, NJ. Bundy, L.G., R.P. Wolkowski, and G.G. Weis (1986). Nitrogen Source Evaluation for Potato Production on Irrigated Sandy Soils. American Potato Journal 63:385-397. Ceryak, R. and D. Hornsby (1996). Groundwater Quality Report : Suwannee River Water Management District, WR-96-02. Live Oak, FL. Charbeneau, R.J. (2000). Groundwater Hydraulic s and Pollutant Transport. Prentice-Hall, Inc.: Upper Saddle River, N.J. Curwen, D. (1993). Water Management. In: R.C. Rowe (ed.). Potato Health Management, American Phytopathological Society, St. Paul, MN, pp 67-75. Dingman, S.L. (1994). Physical Hydrology. Prentice Hall Inc., Upper Saddle River, NJ. Errebhi, M., C.J. Rosen, and S.C. Gupta (1998). Potato Yield Response and Nitrate Leaching as Influenced by Nitrogen Management. Agronomy Journal. volume 90 no 1 (Jan./Feb. 1998):10-15. Graetz, D.A., W.D. Graham, B. Hornsby and Mylavarapy (1999). Evaluating Effectiveness of BMPs for Animal and Fertilizer Management to Reduce Nutrient Inputs into Groundwater in the Suwannee River Basin. Proposal to the EPA 319 Program.

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230 Griffin, T.S., B.S. Johnson, and J.T. Ritchie (1993). A Simulation Model for Potato Growth and Development: SUBSTOR-Potato Version 2.0. IBSNAT Research Report Series 02. Department of Agronomy and Soil Science, University of Hawaii. Honolulu, Hawaii. Ham, L.K. and H.H. Hatzell (1996). Analysis of Nutrients in the Surface Waters of the Georgia-Florida Coastal Plain Study Unit, 1970-91. U.S. Geological Survey WaterResources Investigations Report 96-4037. Hochmuth, G., and K. Cordasco (2000). A Summary of N, P, and K Research on Potato in Florida, University of Florida Extension, IFAS, HS756. Hochmuth, G.J., C.M. Hutchinson, D.N. Maynard, W.M. Stall, T.A. Kucharek, S.E. Webb, T.G. Taylor, S.A. Smith, and E.H. Simonne (2000). Potato Production in Florida, University of Florida Extension, IFAS, HS733 pp. 223-230. Home, P.G., R.K. Panda, and S. Kar (2002) Effect of Method and Scheduling of Irrigation on Water and Nitrogen use Efficiencies of Okra (Ablmoschus esculentus), Agricultural Water Management 55:159-170. Hornsby, D.H., and R. Mattson (1996). Surface Water Quality and Biological Monitoring Network. Suwannee River Water Management District Annual Report WR-96-02. Hornsby, D.H. and R. Ceryak (1999). Springs of the Suwannee River Basin in Florida. Suwannee River Water Management District Report WR99-02. Hornsby, D.H. (February 2000). Abstract: Nitrate-Nitrogen in the Suwannee River, Florida Springs Conference Natural Gems Troubled Waters, Sheraton Gainesville Hotel, Gainesville, FL. Katz, B. (February 2000). Abstract: Sources of Nitrate Contamination of Spring Waters, Suwannee River Basin, Florida, Sheraton Gainesville Hotel, Gainesville, FL. Katz, B.G. (1992). Hydrochemistry of the Upper Floridan aquifer, Florida. U.S. Geological Survey Water-Resources Investigation Report 91-4196. Katz, B.G. and R.S. DeHan. (1996). The Suwannee River Basin Pilot Study Issues for Watershed Management in Florida. U.S. Department of the Interior U.S. Geological Survey Fact Sheet FS-080-96. Katz, B.G., D.H. Hornsby, F.B. Johnkari, and M.F. Mokray (1999). Sources of Chronology of Nitrate Contamination in Spring Waters, Suwannee River Basin, Florida. U.S. Geological Survey Water-Resources Investigations Report 99-4252. King, B.A. and J.C. Stark (1997). Potato Irrigation Management. University of Idaho Cooperative Extension System. College of Agriculture, BUL 789.

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231 Maddox, G.L., J.M. Lloyd, T.M. Scott, S.B. Upchurch, and R. Copeland. (1992). Floridas Ground-Water Quality Monitoring Network Program: Background Hydrogeochemistry. Florida Geological Survey Special Publication 34. Mueller, D.K. and D.R. Helsel (1996). Nutrients in the Nations Waters-Too M uch of a Good Thing?: U.S. Geological Survey Circular 1136. Neetson, J.J. (1990). Development of N itrogen Fertilizer Recommendations for Arable Crops in the Netherlands in Relation to Nitrate Leaching. Fertilizer Research 26: 291-298. Ojala, J.C., J.C. Stark, and G.E. Kleinkopf (1990). Influence of Irrigation and Nitrogen Management on Potato Yield and Quality. American Potato Journal 67:29-43. Osaki, M., T. Nakamura, and T. Tandano (1992). Production Efficiency of Nitrogen Absorbed by Potato Plant at Various Growth Stages. Soil Science and Plant Nutrition Journal 39(4):583-593. Paramasivam, S., A.K. Alva, and A. Fare s (2000). Transformation and Transport of Nitrogen Forms in a Sandy Entisol Following a Heavy Loading of Ammonium Nitrate Solution: Field Measurements and Model Simulations. Journal of Soil Contamination 9(1):65-86. Pittman, J.R., H.H. Hatzell, and E.T. Oaksford (1997). Spring Contributions to Water Quality and Nitrate Loads in the Suwannee River during Base Flow in July 1995. U.S. Geological Survey Water-Resources Investigations Report 97-4152. Priestly, C.H. and R.J. Taylor (1972). On the Assessment of Surface Heat Flux and Evaporation using Large-Scale Parameters. Monthly Weather Review 100:81-92. Roberts, S, W.H. Weaver, and J.P. Phelps (1982). Effect of Rate and Time of Fertilization on Nitrogen and Yield of Russe t Burbank Potatoes under Center Pivot Irrigation. American Potato Journal 59:77-86. Roberts, S., H.H. Cheng, and F.O. Farrow (1991). Potato Uptake and Recovery of Nitrogen-15-Enriched Ammonium Nitr ate from Periodic Applications. Agronomy Journal 83:378-381. Simonne, E.H, M.D. Dukes, and D.Z. Hama n (2001-2002). Principles and Practices of Irrigation Management for Vegetables. University of Florida Extension, IFAS. Vegetable Production Guide for Florida 31-37. Simunek, J., M. Sejna, and T.V. Ge nuchten (1999). HYDRUS-2D/MESHEGEN-2D. Simulating Water Flow and Solute Transport in Two-Dimensional Variably Saturated Media. International Ground Water Modeling Center. Colorado School of Mines. Golden, CO.

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232 Sullivan, D.M., J.M. Hart, and N.W. Christensen (1999). Nitrogen Uptake and Utilization by Pacific Northwest Crops. A Pacific Northwest Extension Publication Extension and Station Communications Or egon State University. Corvallis, OR. Tanner, C.B., G.G. Weis, and D. Curwen (1982). Russet Burbank Rooting in Sandy Soils with Pans following Deep Plowing. American. Potato Journal 59:107-112. Tsuji, G.Y., G. Uehara, and S. Balas (1994). DSSAT Users Manual. International Benchmark Sites Network for Agrotechnology Transfer. University of Hawaii, Honolulu, Hawaii. Tsuji, G.Y, G. Hoogenboom, P.K. Thorton (1998). Understanding Options for Agricultural Production, pp 41-54. Kluwer Academic Publishers, Boston, MA. Unlu, K., G. Ozernirler, and C. Yurteri (1999). Nitrogen Fertilizer Leaching from Cropped and Irrigated Sandy Soil in Central Turkey. European Journal of Soil Science 50: 609-620. Verhagen, J. (1997). Site Specific Fertiliser Application for Potato Production and Effects on N-Leaching using Dynamics Simulatin Modelling. Agriculture, Ecosystems and Environment 66 (1997) 165-175. Waddell, J.T., S.C. Gupta, J.F. Moncrief, C.J. Rosen, and D.D. Steele (1999). Irrigation Management Effects on Potato Yield, Tuber Quality, and Nitrogen Uptake, Agronomy Journal 91:991-997. Zvomuya, F., C.J. Rosen, M.P. Russelle, and S.C. Gupta (2003). Ground Water Quality. Journal of Environmental Quality 32:480-489.

PAGE 247

233 BIOGRAPHICAL SKETCH Frank Warren McKinnie was born on October 13, 1977, in Marianna, FL, and grew up in Grand Ridge, FL. After graduating from Sneads High School in 1996, he enrolled at Chipola Junior College in Marianna, FL where he received an Associate of Arts degree in pre-engineering curriculum. In fall of 1999, he enrolled in the Electrical Engineering Department at the University of Florida. At the beginning of the semester, he changed his major to agricultural and biological engineering with emphasis in soil and water engineering because he was not content with the engineering discipline he had initially selected. On May 5, 2001, Frank graduated with his Bachelor of Science in Agricultural and Biological Engineering w ith highest honors. In August 2001, he enrolled at the Agricultural and Biological E ngineering Department where he focused his studies on water resources, specifically subsurface contaminant transport.


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Title: Monitoring and Modeling Water and Nitrogen Transport in the Vadose Zone of a Vegetable Farm in the Suwannee River Basin
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Material Information

Title: Monitoring and Modeling Water and Nitrogen Transport in the Vadose Zone of a Vegetable Farm in the Suwannee River Basin
Physical Description: Mixed Material
Copyright Date: 2008

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MONITORING AND MODELING WATER AND NITROGEN TRANSPORT
IN THE VADOSE ZONE OF A VEGETABLE FARM
IN THE SUWANNEE RIVER BASIN

















By

FRANK WARREN MCKINNIE


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ENGINEERING

UNIVERSITY OF FLORIDA


2003

































Copyright 2003

by

Frank Warren McKinnie

































This document is dedicated to my family and friends















ACKNOWLEDGMENTS

First, I would like to thank my graduate committee chairperson, Dr. Wendy

Graham, who has helped me gain so much knowledge from this experience and whose

assistance throughout my time in graduate school has exceeded all my expectations. I

would also like to thank all my family and friends who have made the past five years in

Gainesville, FL, at the University of Florida one of the best experiences of my life.

Special thanks go to my mother, father, grandmother, and brother for their continual love,

support, and encouragement throughout my time in graduate school and my life. I would

also like to thank Ken and Joe Hall for their assistance and cooperation with the research

project; Dr. James Jones, Dr. Jennifer Jacobs, and Dr. Donald Graetz for serving on my

committee and for their assistance and guidance; Mike Albert, Jeff Williams, and Wayne

Williams for their assistance on the research project both on and off the field; Dawn

Lucas for analyzing all those soil samples; all my professors for their dedication to

teaching and research; Cheryl Porter for assistance with the DSSAT modifications; and

all the faculty and staff at the Agricultural and Biological Engineering Department.
















TABLE OF CONTENTS

Page

A C K N O W L E D G M E N T S ................................................................................................. iv

LIST OF TABLES .................................................... .......... .............. viii

LIST OF FIGURES ......... ......................... ...... ........ ............ ix

CHAPTER

1 IN TR OD U CTION ............................................... .. ......................... ..

B a c k g ro u n d ............................................................................................. 1
O bjectiv e s ................................................................... ................................. . .3
Literature R review ................................................................ 3
Suw annee R iv er B asin .............................................................. ............... 3
N itrogen C ycle.................................................... 5
Potato Crop M anagem ent .............................................................. .............. 7

2 FIELD EXPERIMENTS AND METHODOLOGIES..................... ..............13

S ite D e sc rip tio n .................................................................................................... 1 3
Field Sampling M ethodologies ............................................................. ............ 14
F ie ld R e su lts ......................................................................................................... 1 7
Spring 2001 Potato Crop ........................ ........................18
Planting details, crop management, and weather .......................................18
M oisture content results ....................................................... 19
N itrate-nitrogen results .................................................................. ..... 21
C rop m monitoring results........... .................................... ........ .............. 24
Spring 2002 P otato C rop ......................... .......................... ............... ... 26
Planting details, crop management and weather .......................................26
North half moisture content results .................................. ...............27
South half moisture content results ................................... ...............29
North half bed nitrate-nitrogen results ................ .........................1...
South half bed nitrate-nitrogen results .................................... ............... 35
North half furrow nitrate-nitrogen results ..................................................37
South half furrow nitrate-nitrogen results ...................................................38
C rop m monitoring .................. ........ ... ... ........ ............... ...42
Comparisons of Final Yield/Nitrogen Lost and Nitrogen Applied ............................44



v









3 MODEL DESCRIPTION AND RESULTS .................................... ............... 47

D S SA T M odel D description .............................................................. .....................47
Hydrology Component ............................................ ............... 48
N itrogen C om p on ent ........................................ ............................................50
Crop Growth Component .................. .................................. 51
M odel Calibration and Results ............................................................................53

4 D SSA T M OD IFICA TION S ............................................... ............................ 67

H Y D R U S M odel D description ......................................................................... ...... 68
Governing Flow Equation ............................................................................69
R oot W ater U ptake ........................................................................ .............. 70
The Unsaturated Soil Hydraulic Properties...................................................71
Governing Transport Equation.... ................... .................72
HYDRUS Results and DSSAT Modifications ................................. ...............74
H YD RU S R results ............................................. .. ....... ................. 74
D SSA T M modifications ............................................................ ............... 81

5 MODIFIED DSSAT RESULTS AND DISCUSSION ...............................................85

Soil-W ater T ran sport R results .......................................................... .....................85
2001 Potato Crop .................. ............................ .. .... ................. 85
2002 Potato Crop ............................................... ........ ................. 89
N itrate-N itrogen Transport Results ........................................ ........................ 93
2001 Potato Crop .................. ............................ .. ..... ................. 93
2002 Potato Crop .................. ............................ .. ...... ................. 96
Crop Growth Results .................................. .. ... ........ ............ 99
2001 Potato Crop .................. .............................. .. .. ........ .............. .. 99
2002 Potato Crop .................. .......................... .... .... ................. 102

6 CONCLUSIONS ...............................................................108

APPENDIX

A SOIL SAMPLE ANALYSIS RESULTS......................................................115

B PLANT SAMPLE ANALYSIS RESULTS...................... ...... ............... 136

C SUBSTOR/DSSAT INPUT FILES ............................. 140

D H YD RU S IN PU T FILES ................................................ ............................. 156

E D SSA T M OD IFICA TION S ............................................. ............................ 212

F MODIFIED DSSAT/SUBSTOR INPUT FILES.................... ..................................216

LIST O F R EFER EN CE S ........................................................................... .............229









B IO G R A PH IC A L SK E T C H ........................................... ...........................................233
















LIST OF TABLES


Table pge

2-1. Retentivity data measured at the research site. .............................. ............... .14

2-2. Spring 2001 potato crop planting information obtained from farmer....................18

2-4. Statistical analysis of 2001 north half soil samples moisture content results. .........20

2-5. Important dates related to planting, harvest, and phenological events (2001). .......24

2-6. Spring 2002 approximate nitrogen fertilizer schedule and amounts......................27

2-7. The standard deviations of the 2002 north half measured volumetric moisture
contents..................................... ................................... ......... 29

2-8. The standard deviations of the 2002 south half measured moisture contents..........31

2-9. Nitrate-nitrogen content results for north soil samples taken on May 1, 2002 for
w ells. ............................................................................... 34

2-10. Statistical analysis of spring 2002 furrow soil samples nitrate-nitrogen results......40

2-11. Important dates related to planting, harvest, and phenological events (2002). .......42

A-1. Soil sample results at the project site. ....................... ................ .. ..............116

B -1. Potato crop analysis results (2001)................................................ .................. 137

B-2. Potato crop analysis results (2002).................................. .......................... 138















LIST OF FIGURES


Figure p

1-1. Suwannee River Basin (Pittman et al., 1997).............. ............................................1

2-1. North half average moisture contents for the spring 2001 potato crop ..................19

2-2. Average 2001 north half nitrate-nitrogen content in top 90 cm of the bed area. .....22

2-3. North half cumulative nitrogen applied and total crop uptake (2001). ..................26

2-4. North half average volumetric moisture contents for the spring 2002 potato crop
in the center of bed. .................................. .. .. ...... .. ............28

2-5. South half average volumetric moisture contents for the spring 2002 potato crop
in the center of bed. ............................. .... .................. .. .. ...... .... ...........30

2-6. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center
o f b e d ............................................................................ 3 2

2-7. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center
o f b e d ............................................................................ 3 5

2-8. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the center
of fu rrow ...................................... ................................. ......... ...... 3 8

2-9. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the center
of fu rrow ...................................... ................................. ......... ...... 3 9

2-10. Nitrogen applied and total crop uptake (2002)............................................. 44

2-11. Comparison between the total nitrogen applied and the dry tuber yield ................45

3-1. DSSAT spring 2001 potato crop soil moisture content results for the north half at
0 -1 5 cm ............................................................................. 5 5

3-2. DSSAT spring 2001 potato crop soil moisture content results for the north half at
15 -3 0 cm ............................................................................5 6

3-3. DSSAT spring 2001 potato crop soil moisture content results for the north half at
3 0 -6 0 cm ............................................................................5 6









3-4. DSSAT spring 2001 potato crop soil moisture content results for the north half at
6 0 -9 0 cm ............................................................................5 7

3-5. Cumulative water balance for the north half of the field for the spring 2001 potato
c ro p ......... .. ......... ................ ....... ................................................ . 5 8

3-6. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of
the field at 0-15 cm ............. ......... .. ....................... 60

3-7. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of
the field at 15-30 cm ........... ................................... .... ........ 60

3-8. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of
the fi eld at 30-60 cm ......... .......... ...................................................... ..6 1

3-9. Spring 2001 potato crop nitrate-nitrogen concentration results for the north half of
th e field at 6 0 -9 0 cm ......... .. .................................................. ........ ........ 6 1

3-10. DSSAT dry leaf weight predictions for the spring 2001 potato crop on the north
half of the field. .............. .................................................................... ..... 63

3-11. DSSAT dry stem weight predictions for the spring 2001 potato crop on the north
half of the field. .............. .................................................................... ..... 64

3-12. DSSAT dry tuber weight predictions for the spring 2001 potato crop on the north
half of the field. .............. .................................................................... ..... 64

3-13. Cumulative nitrogen balance for the spring 2001 potato crop on the north half of
th e fie ld ......... .. ......... ................ ....... .......... ........................................ 6 5

4-1. Illustrations of the potato plant beds (01/28/2003) and root distribution
(04/12/2003). .........................................................................67

4-2. SMCC of the hydraulic conductivity versus moisture content using the Brooks
and C orey equation ............ .............................................................. .... .... ..... .. 76

4-3. SMCC of the soil matric potential versus moisture content for the top 45 cm of
the soil profile using the Brooks and Corey equation. ...........................................76

4-4. SMCC of the soil matric potential versus moisture content for the bottom 45 cm
of the soil profile using the Brooks and Corey equation ......................................77

4-5. Flat upper boundary nitrate concentration spectral map for the top 90 cm on the
north half of the field for 01/10/02 through 01/14/02 (a-e)............... ...................79

4-6. Irregularly shaped upper boundary nitrate concentration spectral map for the top
90 cm on the north half of the field for 01/10/02 through 01/14/02 (a-e) ................80









4-7. Cumulative nitrate-nitrogen leached out of the top 90-cm from the January 10,
2002 fertilizer application. .............................................. ............................. 81

4-8. A comparison of the light interception and root domain for flat (a) and bedded (b)
ro w s ............................................................. ................ 8 3

4-9. Potato plant canopy illustration ................................................................... .. ..... 84

5-1. Comparisons between the predicted and measured moisture contents at 0-15 cm
for the north half of the field 2001 potato crop.......................................................86

5-2. Comparisons between the predicted and measured moisture contents at 15-30 cm
for the north half of the field 2001 potato crop. ...................................................87

5-3. Comparisons between the predicted and measured moisture contents at 30-60 cm
for the north half of the field 2001 potato crop. ...................................................87

5-4. Comparisons between the predicted and measured moisture contents at 60-90 cm
for the north half of the field 2001 potato crop. ...................................................88

5-5. Cumulative water balance for the north half of the field for the spring 2001 potato
c ro p .......................................................................................... . 8 8

5-6. Comparisons between the predicted and measured moisture contents at 0-15 cm
for the 2002 potato crop ........................................ ............................................90

5-7. Comparisons between the predicted and measured moisture contents at 15-30 cm
for the 2002 potato crop ........................................ ............................................90

5-8. Comparisons between the predicted and measured moisture contents at 30-60 cm
for the 2002 potato crop ........................................ ............................................9 1

5-9. Comparisons between the predicted and measured moisture contents at 60-90 cm
for the 2002 potato crop ........................................ ............................................9 1

5-10. Cumulative water balance for the north half of the field for the spring 2002 potato
c ro p .......................................................................................... . 9 2

5-11. Cumulative water balance for the south half of the field for the spring 2002 potato
c ro p .......................................................................................... . 9 3

5-12. Comparisons between the predicted and measured nitrate-nitrogen contents at
0-15 cm for the north half of the field (2001). ...................................................94

5-13. Comparisons between the predicted and measured nitrate-nitrogen contents at
15-30 cm for the north half of the field (2001). ...................................................94

5-14. Comparisons between the predicted and measured nitrate-nitrogen contents at
30-60 cm for the north half of the field (2001). ...................................................95









5-15. Comparisons between the predicted and measured nitrate-nitrogen contents at
60-90 cm for the north half of the field (2001). ............. ......................................95

5-16. Comparisons between the predicted and measured nitrate-nitrogen concentrations
at 0-15 cm (2002). ..................................................................... 97

5-17. Comparisons between the predicted and measured nitrate-nitrogen concentrations
at 15-30 cm (2002). .....................................................................97

5-18. Comparisons between the predicted and measured nitrate-nitrogen concentrations
at 30-60 cm (2002). ........................... ...................... .. .. ....... .... ..... 98

5-19. Comparisons between the predicted and measured nitrate-nitrogen concentrations
at 60-90 cm (2002). ................................................ ...............98

5-20. Cumulative nitrogen balance for the 2001 potato crop on the north half of the
field ...................................................... .... ................. 10 0

5-21. Dry leaf weight predictions for the spring 2001 potato crop on the north half of
th e fie ld ...................................... ................................................. 1 0 0

5-22. Dry stem weight predictions for the spring 2001 potato crop on the north half of
th e fie ld ...................................... ................................................. 1 0 1

5-23. Dry tuber weight predictions for the spring 2001 potato crop on the north half of
th e fie ld ...................................... ................................................. 1 0 1

5-24. North half cumulative nitrogen balance for the2002 potato crop. .......................103

5-25. South half cumulative nitrogen balance for the 2002 potato crop. ......................103

5-26. North half dry leaf weight predictions for the spring 2002 potato crop............... 104

5-27. South half dry leaf weight predictions for the spring 2002 potato crop............... 104

5-28. North half dry stem weight predictions for the spring 2002 potato crop .............105

5-29. South half dry stem weight predictions for the spring 2002 potato crop .............105

5-30. North half dry tuber weight predictions for the spring 2002 potato crop.............106

5-31. South half dry tuber weight predictions for the spring 2002 potato crop............. 106















Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering

MONITORING AND MODELING WATER AND NITROGEN TRANSPORT IN THE
VADOSE ZONE OF A VEGETABLE FARM IN THE SUWANNEE RIVER BASIN

By

Frank Warren McKinnie

August 2003

Chair: Wendy D. Graham
Major Department: Agricultural and Biological Engineering

The Suwannee River Basin has become a source of major concern over recent years

due to the increased nitrogen loads within the basin. In 1995, nitrate loads increased

from 2,300 to 6,000 kg/day over a 53.1 km reach of the Suwannee River that began in

Dowling Park, FL and ended in Branford, FL. Eighty-nine percent of the increase

occurred in the lower 2/3 of the reach. With the increasing nitrogen loads, it is evident

that serious problems may arise if nothing is done to correct the current situation.

The ultimate goal of this research was to develop Best Management Practices

(BMPs) to reduce nutrient loadings to the ground water from vegetable farms in the

Suwannee River Basin. To achieve the objective, nitrogen and water transport in the

vadose zone was monitored and modeled under a 56.7 ha center pivot at a 2020 ha

vegetable farm just west of O'Brien, FL. This farm lies just a few miles from the

Suwannee River in the upstream direction of ground water flow. The sandy soils on the









farm are extremely susceptible to leaching nitrogen out of the vadose zone and into the

underlying Floridan Aquifer.

Monitoring well samples, soils samples, and plant samples was used to obtain

onsite nitrogen, plant, and soil moisture information over time to track nitrogen

movement and calibrate mathematical models. The measured data show that the sandy

soils at the project are highly susceptible to leaching nitrate-nitrogen following rainfall

events and irrigation applications. The data collected in 2001 show that 24% of the total

nitrogen applied (fertilizer plus irrigation nitrate-nitrogen) to the north half of the field

was recovered by the potato plants, leaving 325 kg/ha of the 427 kg/ha nitrogen applied

in the fertilizer and irrigation to be leached out of the soil profile and into the underlying

Floridan Aquifer. The 2002 data indicate that the potato crops currently grown at the

project site are receiving more than adequate amounts of nitrogen fertilizer and irrigation.

The DSSAT35 crop model and the HYDRUS2D vadose zone model were used to

produce an estimate of the total load and concentration of nitrogen and the quantity of

water leaching through the vadose zone into the Floridan Aquifer. The DSSAT model

significantly over predicted the volume of water drained out of the top 90 cm, which

directly affects the nitrate-nitrogen leaching. As a results, the 2001 potato crop

simulation results show that the DSSAT model under predicted the dry tuber yield by

3,105 kg/ha relative to the 6,840 kg/ha measured. These results indicate that DSSAT is

unable to accurately predict potato crop growth on sandy soils located at the project site.

Results from the 2001 calibration and from the HYDRUS simulations illustrate the

importance of incorporating multi-dimensional water and nutrient transport and the need

to replace or improve upon the current methods implemented by the DSSAT plant model.















CHAPTER 1
INTRODUCTION

Background

The Suwannee River Basin, shown in Figure 1-1, has become a source of major

concern over recent years due to increased nitrogen loads within the basin. The sandy

soils located in the basin are susceptible to nitrogen leaching into the underlying Floridan

Aquifer. In 1995, Pittman et al. (1997) conducted a study, during base flow, on a 53.1

km reach of the Suwannee River that began in Dowling Park, FL, and ended in Branford,

FL (Figure 1-1).



MADISON
COUNTY o JN
51 Live
Oak


Figure 1-1. Suwannee River Basin (Pittman et al., 1997)









Results from the study showed that the nitrogen loads increased from 2,300 kg/day

to 6,000 kg/day over the entire reach with 89% of the increase occurring in the lower 2/3

of the reach. Ham and Hatzell (1996) found that nitrate concentrations in the Suwannee

River increased at a rate of 0.02 mg/L per year over a twenty-year period from 1971-

1991. The source of the increased nitrogen loads is not evident because of several

possible non-point sources of the pollution, which include dairy farms, row-crop farms,

poultry farms, residential communities, etc. The waters in the basin are used for

recreation, a potable water source, and support an intricate diverse ecosystem. With the

increasing nitrogen loads, it is evident that serious problems may eventually arise if

nothing is done to alleviate the current problem.

In an attempt to determine the possible sources of the increased nitrogen loads, a

joint research venture involving the University of Florida, Suwannee River Water

Management District (SRWMD), the Florida Department of Agricultural and Consumer

Services (FDACS), and the Florida Department of Environmental Protection (FDEP) was

developed. The overall purpose of the study was to evaluate nitrate loadings from three

different agricultural operations (including a dairy farm, poultry farm, and row-crop

farm) to the Floridan Aquifer. The primary focus of the research reported here is the

study conducted at the row-crop operation located in O'Brien, FL, approximately 16-km

northwest ofBranford, FL (Figure 1-1). The cultivars grown on the 2,020-ha farm

include crops such as corn, peanuts, soybean, potatoes, etc. Several of the crops grown

on the farm are known to have poor recovery of applied nitrogen. Of these crops,

potatoes appear to contribute a large amount of the cumulative nitrogen being leached out

of the vadose zone and into the Floridan Aquifer (Albert, 2002).









In an effort to evaluate and reduce the amount of nitrogen being leached out of the

soil profile, potato crops have been studied since spring 2001. By studying the system

and processes that influence the nitrogen and water transport, a better understanding of

the system can be developed that can aid in the development of an effective best

management practice (BMP).

Objectives

The objectives of this research included monitoring nitrate and water transport in

the vadose zone on a 56.7 ha potato field located at Pivot 12 of the research farm, and

implementing a mathematical model that can accurately predict the spatial and temporal

distribution of nitrate and water in the soil profile as well as crop yield. These objectives

were developed to assist in reaching the goals outlined by the FDEP, FDACS, and

SRWMD funded project to develop BMPs for the arable crops in the region.

Literature Review

Suwannee River Basin

The Suwannee River basin comprises an area of 25,770 km2 with 43% of the total

area located in north central Florida. The primary land use in the Florida portion of the

basin is agriculture, including forestry, pasture, row crops, and intensive animal

husbandry (Hornsby, 2000). The basin has several karst characteristics that result in a

direct linkage between the surface and ground waters, resulting in a single dynamic flow

system (Katz et al., 1996). As a result of the land use and direct interactions between

surface and ground waters, there has been a noticeable increase in nitrate-nitrogen

concentrations in surface and ground waters in the basin. Over the past 40 years, the

nitrate-nitrogen concentrations in many of the springs in the Suwannee River basin have

increased from less than 0.1 mg/L (Katz, 1992; Maddox et al., 1992) to more than 5 mg/L









(Hornsby and Ceryak, 1999), which has resulted in high nitrogen loading rates in the

Suwannee and Santa Fe Rivers (Katz, 2000). The total nitrate-nitrogen load in the basin

in the 1998 water year was estimated to be 7,113 tons with 45.5% of the increase

occurring in the middle Suwannee River Basin (Hornsby, 2000).

The Suwannee River is the second largest river in Florida with a mean annual flow

of 6.7 billion gallons per day, and is designated as an "Outstanding Florida Water". Katz

and Dehan (1996) found that the high nitrate-nitrogen levels in the Suwannee River and

in parts of the Upper Floridan Aquifer were caused by the high nitrogen loading from the

wastes generated by poultry and dairy farms, and fertilizers applied to cropland along the

Suwannee River in Lafayette and Suwannee Counties. Ceryak and Hornsby (1996)

reported that the median nitrate-nitrogen concentration of the ground water near the

Suwannee River between Ellaville, FL and Branford, FL ranged from 0.5 mg/L to 4.0

mg/L. The high nitrate-nitrogen concentrations near Branford, FL were attributed to

ground water discharge because there are no major stream inputs to the Suwannee River

in this region of the middle Suwannee River Basin (Katz et al., 1999). Also, these

researchers concluded that the elevated nitrate-nitrogen concentrations during low flow

periods increase the probability that the ground water inflow from springs and riverbed

leakage were the cause of the increased nitrate concentrations and loads in the lower

Suwannee River.

These high nitrogen concentrations can eventually have detrimental effects on the

Suwannee River basin ecosystem and on human health. Eutrophication can occur due to

elevated nitrate-nitrogen concentrations in rivers, which results in algal blooms and

depletion of dissolved oxygen in the water that can lead to fish kills. The Environmental









Protection Agency (EPA) has set a maximum contaminant level (10 mg/L) for nitrate-

nitrogen in drinking water to reduce the possibility of human health complications

resulting from high nitrate-nitrogen concentrations. The limit was set because of the

health risk to infants who consume high-nitrate water, who may contract

methemoglobinemia (Mueller and Helsel, 1996).

Nitrogen Cycle

Elevated nitrogen concentrations in surface and ground waters have resulted in

extensive studies related to nitrogen load contributions from many non-point sources of

pollution. Leaching is the primary mechanism that contributes to the increased nitrogen

loads, especially in sandy soils. But to fully understand nitrogen transport in the soil, the

dynamics of the nitrogen cycle must be thoroughly understood.

The nitrogen cycle is a complex system that has many factors that affect nitrogen

transport. Nitrogen exists in soils as both inorganic and organic forms. Nitrogen sources

for the soil include fertilizers, atmospheric nitrogen fixation by plants, nitrogen

deposition by lightning, and animal waste. Nitrogen is primarily removed from the soil

through leaching, but is also removed by erosion and runoff, plant uptake of ammonium

and nitrate, denitrification of nitrate, and volatization of ammonia. There are several

chemical processes that affect nitrogen content in the soil, but the two microbial

processes that primarily dictate the amount of nitrogen available for transport and plant

availability of natural systems are mineralization and immobilization. Mineralization is

the process by which ammonia is released from organic matter. Immobilization is the

reverse reaction by which inorganic forms of nitrogen are converted to organic forms.

Inorganic forms of nitrogen are the most common forms of fertilizer used by farming

operations and are the most susceptible to chemical transport. Typical forms of inorganic









nitrogen used as fertilizer are ammonium, anhydrous ammonia, urea, and ammonium-

nitrate. Some inorganic fertilizers go through chemical transformations, which make

nitrogen readily available to plants. For instance, ammonium is a compound transformed

by a process that is termed nitrification into nitrate, which is the form of nitrogen that is

more available to plants compared to NH4+ sources (Roberts et al., 1991).

Nitrification is the process by which ammonium (NH4+) is transformed into nitrate

(NO3-). The process is a two-step reaction that requires autotrophic bacteria

(Nitrosomonas) to convert NH4 to nitrite (NO2-). Then, a second group of autrophs

(Nitrobacter) rapidly converts nitrite to NO3-. Knowing the characteristics of the

nitrification process and the charge of each ion, it is possible to determine the mobility of

nitrogen during certain stages of the transformation. Ammonium is a positively charged

ion that readily sorbs to negatively charged soil colloids, which can reduce its mobility in

the soil. Nitrite and nitrate are both highly mobile forms of nitrogen. Both forms of

nitrogen are negatively charged, which results in negligible interaction and sorption to

soil colloids. Also, nitrite and nitrate forms dissolve quite easily in water. As a result,

nitrite and nitrate are extremely susceptible to leaching by advection when adequate

water is available. However, nitrate is the primary focus of most nitrogen contamination

studies because the transformation of nitrite to nitrate occurs relatively quickly and nitrite

is usually found in small quantities.

By knowing the mobility of certain forms of nitrogen, it is possible to determine

effective types of fertilizers that can be applied to crops to reduce leaching. The most

common forms of nitrogen fertilizer that reduce leaching include those that contain

ammonium compounds. Ammonium's adsorption to the soil colloids renders it less









susceptible to leaching out of the soil (Paramasivam, 2000) and can be an acceptable

form of fertilizer that can reduce total nitrogen leaching. The most common types used

are ammonium nitrate, anhydrous ammonia, and ammonium sulfate. Bundy et al. (1986)

observed significantly higher yields in potatoes when ammonium sulfate was used

instead of nitrate fertilizer and concluded that the higher yields were attributed to the

nitrate fertilizer leaching out of the root zone more easily than the ammonium sulfate.

Extensive research has been conducted over recent years examining the chemical

transport of fertilizers, specifically nitrogen fertilizers, due to concerns about water

quality pertaining to nitrate-nitrogen leaching into the ground water. Leaching occurs

when excess water flows through the bottom boundary of the root system. Factors that

affect nitrate-nitrogen leaching on agricultural lands include soil type, organic matter

content, moisture content, plant rooting depth, irrigation management, fertilizer

management, etc. Of these, irrigation and nitrogen fertilizer management are perhaps the

most important factors that influence nitrate-nitrogen leaching in Florida's sandy soils.

Potato Crop Management

Potatoes (solanum tuberosum) grown in Florida are generally planted in spring and

represent a substantial portion of the total vegetable industry in Florida. In 1996-1997,

potato production in Florida represented 6.1% of the state's $1.6 billion vegetable

industry with 81% of the potatoes harvested during May and June following spring

planting (Hochmuth and Cordasco, 2000). The production of most fresh vegetables

usually requires large applications of nitrogen and irrigation water (Home et al., 2002).

Thus, the two most important aspects of potato production are usually related to proper

irrigation and nitrogen management (Waddell, 1999).









Proper irrigation management is essential to achieve acceptable potato yields in

areas with inadequate rainfall and soils with low water holding capacity. Even though

potatoes are generally grown in areas where sandy soils are present, the plants have

relatively shallow root systems (46-60 cm) because of the low root penetration strength

of the plant roots. As a result, misconceptions often arise that potatoes are a high water

use crop. However, there are many other crops that have equal or greater water

requirements (King and Stark, 1997). In reality, potatoes are sensitive to water stress due

to their complex physiological responses to moderate plant water deficits (Curwen,

1993). Ojala et al. (1990) stated that to achieve maximum productivity for potatoes, the

soil must be consistently kept moist. Hochmuth et al. (2000) reported that potato plant

water requirements for potatoes in Florida varied over the season increasing from 40% of

the reference evapotranspiration (ETo) during initial plant growth periods to

approximately 110% of ETo at peak growth and tuber development and then decreasing

to 70% of ETo during the final growth period of tuber development.

King and Stark (1997) showed that potatoes are particularly sensitive to water

stress during tuber initiation and early tuber development. They also determined that

water stress during tuber bulking has more of an effect on tuber yield than quality. Also,

water stress accelerates leaf senescence and disrupts new leaf formation, which results in

an unrecoverable loss of tuber bulking. Belanger et al. (2000) showed that supplemental

irrigation could improve yield significantly during dry years. From their trials, the

average yield increase in irrigated versus non-irrigated crops was 6.5 tons/ha and 5.1

tons/ha for the total and marketable yields, respectively.









Even though supplemental irrigation is essential for potato production, over

irrigation can also have negative impacts on potato yield. Providing excess water at

planting promotes seed piece decay, delays emergence because of decreased soil

temperature, and leaches nitrate-nitrogen out of the root zone causing nitrogen deficient

plants (King and Stark, 1997). Belanger et al. (2000) concluded that excess water could

result in negligible increases or even decreases in final yield. These findings demonstrate

the importance of proper irrigation scheduling and the need for an adequate irrigation

system that can apply supplemental light water applications uniformly, frequently, and

economically.

Poor irrigation scheduling can have adverse effects on nutrient availability for

potatoes, especially nitrogen. Nitrogen is usually the most limiting nutrient for potato

growth, especially in sandy soil regions (Errebhi et al., 1998). The most readily available

form of nitrogen that potato plants utilize is nitrate-nitrogen, which is also highly mobile

in the soil. Potatoes, in general, have a high demand for nitrogen with a rather low total

recovery (Zvomuya et al., 2003). The low recovery is partially due to the rather shallow

root system of the plants. Potato plants can have a maximum root depth of up to 60 cm,

but 90% of the roots are typically located in the upper 25 cm (Tanner et al., 1982). As a

result, excess water can result in nitrate-nitrogen being leached out of the plant root zone.

Nitrogen fertilizer application scheduling is critical to have adequate potato crop

yield, especially in sandy soils. Nitrogen uptake by potato plants varies depending on the

growth stage of the plants. Even with optimum levels of nitrogen available for plant

uptake, the nitrogen recovery tends to vary considerably. Neetson (1990) found that

potato plants utilized only 50% of the applied fertilizer and Unlu et al. (1999) found that









only 20% was taken up by the plants. Consequently, extensive studies have been

conducted on the nitrogen uptake of potato plants at different growth stages in order to

determine the high demand periods during the potato plant growth cycle. Sullivan et al.

(1999) found that potato plants take up the majority of nitrogen during vine growth of the

vegetative growth stage. Also, it was determined that the total crop uptake of nitrogen

was reached at approximately 100 days after planting during tuber growth. Osaki et al.'s

(1992) research suggests that nitrogen applied after flowering has little or no effect on

final tuber yield. Current IFAS recommendations for Florida, state that the nitrogen

application rate should be approximately 200 kg/ha with roughly 2/3 of the nitrogen

fertilizer band-applied at planting or crop emergence and the remaining fertilizer applied

35 to 40 days later as side-dress (Hochmuth and Cordasco, 2000). With minimal

irrigation application and proper fertilizer timing, maximum fertilizer recovery can be

achieved with reduced leaching and acceptable yields can be maintained.

Irrigation scheduling and fertilizer management significantly influences nitrate-

nitrogen leaching. Errebhi et al. (1998) stated that early applications of nitrogen on sandy

soils could lead to nitrate-nitrogen being leached below the root zone during heavy

rainfall events and excess irrigation. Neetson et al. (1990) found that nitrogen application

recommendation of potato crops in sandy soils of the Netherlands were too large, which

increased the probability of nitrate-nitrogen leaching. The researchers' modeled results

indicated that the current Dutch nitrogen application recommendation (300 kg/ha) could

be reduced by 25% and would result in a total yield decrease of only 2% for clay and

loam soils. Neetson et al. (1990) also determined that the nitrogen application









requirements were higher for sandy soils when compared to the requirements of loams

and clays.

Results from Verhagen's (1997) model simulations using the WAVE model

showed that the current Dutch fertilizer recommendation of 250 kg/ha of nitrogen for

potatoes was too high. During the 1994 experiment, it was determined that using the

current recommendation resulted in 75 kg/ha of nitrate-nitrogen being leached out of the

root zone of loamy soils, which caused the ground water concentrations to exceed the

pre-set standard of 50 mg-NO3/L. Verhagen (1997) further concluded that a 75 to 100-

kg/ha reduction in nitrogen fertilizer would result in dramatic decreases in total nitrogen

leached.

In spring 2001, Albert (2002) conducted a study monitoring and modeling water

and nitrogen transport of a potato crop produced on a 56.7 ha field in the Middle

Suwannee River Basin in O'Brien, FL. Results from this study showed that nitrate-

nitrogen leached rapidly out of the sandy soils located on the vegetable farm. Albert

showed that only 30% of the 313 kg/ha of the applied nitrogen was taken up by the potato

plants. Model results indicated that yields stabilized around 225-kg/ha of applied

nitrogen and that irrigation could have been reduced as much as 30%, resulting in

reduced leaching and acceptable yields. However, there were inconsistencies in the

modeling methods used by Albert (2002). In Albert's first simulations, he found that the

computer model under predicted crop yield considerably. To remedy this problem,

fertilizer applications were doubled in the model's input files because it was thought that

the model simulations were restricted to the bed rather than the entire field area. Since

the fertilizer was band-applied to the bed, it appeared that doubling the fertilizer rate









applied on a field area basis was reasonable. The doubled fertilizer applications produced

fairly accurate results for the 2001 crop. This methodology was subsequently called into

question because the computer model actually simulates the entire area, not just the bed

area as previously thought. After these findings, it was clear that further calibration and

modifications of model were necessary so that it could adequately represent the potato

crop system at the field scale project site.

The main objectives of this research were to extend Albert's previous work of

monitoring and modeling the water and nitrate transport in the vadose zone at the same

research site in O'Brien, FL and to modify the numerical crop model to more accurately

simulate the 2001 and 2002 potato crop data. Once the model is modified and calibrated

properly, it can be implemented as a tool to assist in the development of a BMP that

effectively reduces nitrate-nitrogen leaching and maintains acceptable yields.














CHAPTER 2
FIELD EXPERIMENTS AND METHODOLOGIES

Site Description

The research farm is a 2020-ha row-crop operation located in O'Brien, FL that is

approximately 16-km northwest of Branford. The soils (Penney fine sand) located in this

portion of the Middle Suwannee River Basin are very sandy and susceptible to drought,

so irrigation is critical in the economic viability of the farming operation.

Pivot 12 was selected as the field scale project site based on ground penetrating

radar (GPR) and soil profile evaluation (Albert 2002). The land surface elevations at

pivot 12 range from 13.7 to 15.3 meters above mean sea level (msl). Long-term

piezometric head levels indicate that the average elevation of the top of the Floridan

Aquifer fluctuates from 7.3 meters (annual low) to 8.5 meters (annual high) above msl.

The site has a semi-continuous clay layer that varies from 0.9 to 7.6 meters below the soil

surface based on the GPR analysis of the selected sites by Natural Resources

Conservation Service personnel.

Soil characteristics for the site including the saturated hydraulic conductivity, bulk

density, porosity, field capacity, and wilting point were determined based on laboratory

experiments (Sanchez, oral communication). Results from the laboratory measurements

of the soil-moisture release curve (Table 2-1) indicated that the volumetric moisture

content at field capacity (-345 cm) and wilting point (-15,000 cm) was approximately 6-

7% and 2%, respectively (Albert, 2002). From the laboratory results, it was also

determined that the saturated hydraulic conductivities for the 0-50 cm and 50-100 cm









depths were 4,515 cm/day and 3,759 cm/day, respectively. The bulk densities for the 0-

50 cm and 50-100 cm depths were measured to be 1.48 g/cm3 and 1.56 g/cm3.

Table 2-1. Retentivity data measured at the research site.
Soil Tension Volumetric Moisture Content Volumetric Moisture Content
(cm) (0-50 cm) (50-100 cm)
0 38.8 35.3
4 38.8 35.2
20 35.8 34.4
30 29.9 31.2
45 20.3 17.2
60 14.2 12.6
80 11.1 9.3
100 9.7 8.0
150 8.2 6.9
200 7.3 6.2
345 6.6 5.8
15300 1.8 1.8

Field Sampling Methodologies

In 1999, research began at the project site with periodic monitoring of the Upper

Floridan Aquifer and the vadose zone. The aquifer monitoring consisted of biweekly

shallow groundwater samples and the vadose zone monitoring included taking soil

samples from the soil surface down to the clay layer every six weeks. The data were used

to observe long-term trends in the ground water nitrate-nitrogen concentrations, water

table elevations, and vadose zone soil-water nitrate-nitrogen content at the research farm.

These data results indicate that the leached nitrate-nitrogen from the farm may be a

significant source of the increased nitrogen loads to the Suwannee River Basin (Albert,

2002).

Beginning in 2001, soil samples were taken biweekly from the soil surface to a

depth of 90 cm during the spring potato growing season in addition to the deep soil

samples that were taken every six weeks throughout the year. The samples were taken at

10 locations in the center of the potato plant beds at depths of 0-15, 15-30, 30-60, and 60-









90 cm for the 2001 and 2002 spring potato growing seasons. These soil samples were

taken in close proximity to the 10 wells located on the project site. Refer to Albert (2002,

pp 19) for well locations.

The samples were analyzed at the Department of Soil and Water Science at the

University of Florida for KCL extractable nitrate and ammonium concentrations, bulk

density, and moisture content (Albert, 2002). To determine the moisture contents of the

soil samples, the soil samples were weighed wet then oven dried and reweighed. Results

from the analysis yielded gravimetric water content (Eq. 2-1). Volumetric water content

was then calculated from the gravimetric water content (Eq. 2-2).


6 =mwet (2-1)
mdry

0, = Og Pb (2-2)

where Og is the gravimetric moisture content; Ovo, is the volumetric moisture content; mwet

is the wet weight of the soil sample; mdry is the dry weight of the over-dried sample; pb is

the bulk density of the soil. Appendix A shows the field measurements and detailed

calculations for the spring 2001 and 2002 potato crop soil samples.

The shallow soil samples were taken in order to obtain a more accurate

representation of the water and nitrate movement in the upper portion of the vadose zone

associated with plant roots, which affects nitrogen and water uptake. An on site weather

station was set up in December 2000 approximately 12-km from the project site to record

hourly rainfall, solar radiation, and temperature. Weather station instruments included a

Texas Electronics TR525 rain gauge, a Campbell scientific thermometer, and a LiCor

LI200X pyranometer that were attached to a CR-10X data logger.









During the 2001 and 2002 potato crops, plant biomass sample sets were taken

based on the sampling methodologies outlined in the DSSAT User's Manual (Tsuji et al.,

1999). The biomass sample dates specified by Tsuji et al.. are based on critical growth

stages of the potato crop development including tuber initiation, 20 days after tuber

initiation, and 40 days after tuber initiation. Each biomass harvest consisted of eight

individual samples of average size with two samples taken in each quadrant. In 2001, the

plant samples were taken on a per plant basis, while in 2002 the samples were collected

on a per area basis.

The analysis of the plant samples included dry/wet weight measurements of leaves,

stems, and tubers, measurement of the leaf area index (LAI), and nitrogen content

measurements of the leaves, stems, and tubers. The plants were separated into leaves,

stems, and tubers, then weighed wet. Plant roots were not examined as recommended by

Dr. K.J. Boote (2001, oral communication), because of the negligible amounts of

nitrogen in roots (Albert, 2002). The samples were then dried at 750C in an oven until a

constant weight was reached and reweighed. The dried samples were sent to the

Analytical Research Laboratory at the University of Florida and analyzed for total

kjeldhal nitrogen (TKN). Results from the analysis and calculations are shown in

Appendix B.

In addition to the biomass harvests, a final harvest was conducted at the end of

2001 and 2002 growing seasons to determine final yield. In 2001, twenty, 9.1 m long

sections of row, 10 on each half of the field, were harvested by manually digging up all

the potatoes. At the end of the 2002 growing season, twelve, 7.6 m long sections of row,

three in each quadrant, were harvested manually by digging up the potatoes. The









harvested potatoes were then divided up into three grades based on size, weight, and

quality to determine final tuber yield.

Field Results

The following is a detailed discussion related to the field methods and results of the

spring 2001 and 2002 potato crops. The vadose zone and crops were monitored closely

throughout each crop season in order to accurately estimate the amount of nitrogen

entering the underlying Floridan Aquifer and to determine the nitrogen recovered by the

potato crops.

Two different management practices were used on the north and south halves of the

field for the spring 2001 potato crop. Both management practices were similar except for

a slight reduction in fertilizer application amount applied to the south half of the field.

The north and south halves of the field received 313 and 280 kg/ha of nitrogen fertilizer,

respectively. The irrigation schedule was the same for both halves of the field. As a

result, only the north half results for the 2001 crop are presented in this section.

The spring 2002 potato crop has similar planting details as those of the 2001 crop.

Two management practices were used on the north and south halves of the field in 2002.

The north half of the field received 292 kg/ha of nitrogen fertilizer with the farmer's

typical irrigation management. The south half of the field received 261 kg/ha of nitrogen

fertilizer with a 21% reduction in applied irrigation. The data collection during the spring

2001 and 2002 potato crops were focused on accurately quantifying the movement of

nitrogen for the different management practices implemented at the site.









Spring 2001 Potato Crop

Planting details, crop management, and weather

Essential information including planting geometry, fertilization scheduling, cultivar

type, etc. for the north and south halves of the field were obtained from the farmer and

are shown in Table 2-2 and 2-3. Irrigation amounts were determined from the irrigation

records kept by the farmer and can be found in Appendix C in the SUBSTOR input files

under irrigation. The farmer's irrigation strategy was to maintain the soil moisture at

field capacity in order to meet the crop's water requirement during the growing season.

Table 2-2. Spring 2001 potato crop planting information obtained from farmer.
Cultivar Red LaSoda
Previous Crop Cotton
Planting Depth 15.2 cm
Row Spacing 101 cm
Planting Density* 27,110 plants/ha
Seed Weight 99.2 grams
The actual growing density assumes that only 90% emergence of planting density (24,387
plants/ha).

Table 2-3. Spring 2001 approximate nitrogen fertilizer schedule and amounts.

Applied Nitrogen
(kg/ha)


Date Julian North Half South Half Fertilizer Type/Application
Day Nitrogen Applied Nitrogen Applied Method

01/18/2001 18 38.2 29.2 34-0-0 pre-plant, in bed
02/15/2001 46 16.8 16.8 10-34-0 starter, at plant
03/05/2001 64 112.3 105.5 18-0-0-3 sidedress, liquid
03/25/2001 84 112.3 94.3 18-0-0-3 sidedress, liquid
04/28/2001 118 33.7 33.7 30-0-0, fertigation

As previously stated, weather data were collected from an onsite weather station

that included hourly solar radiation, rainfall, and temperature. The data were downloaded

from the CR-10X periodically.







19


Moisture content results

As previously discussed, the vadose zone monitoring consisted of measurements of

the moisture contents and soil-water nitrogen concentrations over consecutive depths and


times. The soil sampling was comprised of biweekly samplings at depths of 0-15 cm, 15-


30 cm, 30-60 cm, and 60-90 cm. In 2001, soil samples consisted of 10 soil sample sets


taken in the center of the row at different locations.


The results for the average volumetric moisture content of the soils over the


growing season are shown in Figure 2-1.


3/1/01 3/11/01 3/21/01 3/31/01 4/10/01 4/20/01 4/30/01 5/10/01
14 0

12 2

4
100

0)8





12

14

03/01/01 03/11/01 03/21/01 03/31/01 04/10/01 04/20/01 04/30/01 05/10/01
Date



Figure 2-1. North half average moisture contents for the spring 2001 potato crop. Total
water includes rainfall plus irrigation.

The results indicate the entire soil profile tended to remain at or above field


capacity throughout the season. Note that only small fluctuations (Table 2-4) were


observed in the measured moisture contents, due to the frequency that the soil samples


were taken and the well-drained characteristics of the soils located at the project site.


Also, note the moisture contents are above the field capacity of 6% determined in the










laboratory at -345 cm soil matric potential, which indicates that field capacity (or gravity

drained water content) may occur at slightly lower (less negative) tensions than -345 cm.

Table 2-4. Statistical analysis of 2001 north half soil samples moisture content results.


Depth Standard
Date (c) Average (%) Maximum (%) Minimum (%) Devatn )
(cm) Deviation (%)


0-15 8.94 10.82 7.71 1.20
03/0/01 15-30 10.82 19.58 7.71 4.94
03/02/01
30-60 8.43 9.10 6.79 1.10
60-90 10.52 15.95 7.98 3.67

0-15 6.92 7.54 6.38 0.52
15-30 9.08 9.38 8.71 0.32
03/06/01
30-60 9.07 10.62 7.42 1.15
60-90 9.48 11.08 8.39 1.04

0-15 8.95 11.36 7.30 1.53
15-30 9.18 9.90 7.77 0.85
03/24/01
30-60 9.32 10.29 8.26 0.79
60-90 9.25 10.10 8.09 0.78

0-15 7.25 9.12 6.08 1.25
15-30 8.13 9.08 6.74 0.86
04/03/01
30-60 9.14 10.53 8.42 0.82
60-90 9.71 14.09 7.69 2.63

0-15 10.51 12.54 7.82 1.89
15-30 9.73 10.81 8.00 1.05
04/20/01
30-60 9.41 10.45 8.25 0.80
60-90 8.66 9.01 7.78 0.51

0-15 7.33 12.17 4.57 3.07
15-30 12.13 32.75 5.42 11.58
05/04/01
30-60 8.75 9.49 7.81 0.68
60-90 8.32 9.23 7.21 0.74


The relatively high average value shown on 05/04/2001 for the 15-30 cm depth

implies that there may have been various sources error during the analysis of the sample

set. The standard deviation for the 15-30 cm depth was 11.6% (Table 2-4) with

maximum and minimum values of the moisture content measuring to be 32.8% and 5.4%,









respectively. This indicates that the samples may have either been compromised in

storage or that there may have been errors in the moisture content measurements. In any

case, it is obvious that the soils tend to drain to field capacity relatively quickly even

when substantial amounts of water are applied to the crop. For example, from 4/1/2001

to the end of the crop season, the field received approximately 1.0 cm of applied water

daily. This applied water had very little impact on moisture content. The fact that field

capacity was maintained throughout the season, even after large water applications,

provides evidence that the potato crop was over-irrigated. Also, the drainage features of

the soils on the site show that there is little impedance of the downward movement of the

soil-water in the soil profile, which has a large influence on nutrient leaching.

Nitrate-nitrogen results

Figure 2-2 depicts the temporal and spatial nitrate-nitrogen mass transport in the

bed. The figure is a good illustration of how the nitrate-nitrogen moves through the soil

profile and into the Floridan Aquifer. It should be noted that plant roots extend to a

maximum root depth of approximately 30-45 cm, which makes it improbable that any

nutrients are removed from the soil by plants below this depth. Therefore, nutrients

below this depth will eventually enter the underlying Floridan Aquifer. Also it should be

noted that fertilizer application rates were reported on a total field area basis when the

applied nitrogen was actually concentrated in the bed. As a result, the values shown and

discussed for nitrate-nitrogen loads in Figure 2-2 represent the bed area only, and the

reported fertilizer application rates are for the entire field area.

After the pre-plant and starter nitrogen fertilizer applications on January 18, 2001

and February 16, 2001, respectively, there was minimal leaching because there was no

water applied. After March 2, 2001, steady nitrate-nitrogen leaching occurred as a result











of the 1.7 cm rainfall event on March 4, 2001 (see the results for the soil samples taken

on March 6, 2001). Information provided by the grower indicated there was nitrogen

fertilizer applied on March 5, 2001. However, the data indicate that this information may

be inaccurate and fertilizer was actually applied after March 6, 2001. If the fertilizer was

really applied on March 5, 2001, there should have been an increase in the nitrate-

nitrogen content in the soil, but none was found from the soil samples taken on March 6,

2001. Albert (2002) observed that reported and actual fertilization dates had

discrepancies. For example, Albert (2002) stated that it was reported that a fertilizer

application occurred on March 25, 2001 when it was actually observed being applied the

day before.


H2O Applied 11 cm
N-Applied H20 Applied 7 6 cm
350 N-Appled 112 kg/ha (3/24/01) N-Applied 0
350 N-Applhed
38 kg/ha (1/18 01) Aplied 14 8 cm
17 kgha (21161 01) -Appred

aPic ar Applied 16 3 cm1 2
N- Appled17
~250 -H2Applied 1 7 cm
SN-Appleed 5Applied 132cm
At 112kgha(3/5/ 2001) 0th a it te g o i oed
200 4 kgha(42801)









03/02/01 03/06/01 03/24/01 04/03/01 04/20/01 05/04/01 05/25/01 06/06/01
Date
I ..,C,.,- 0 ,., n : : 1., ':h, 1' : I':,: h ,


Figure 2-2. Average 2001 north half nitrate-nitrogen content in top 90 cm of the bed
area. Each depth increment is an average of five samples. The applied
nitrogen is the total nitrogen applied for the total area. All fertilizer
application dates are approximate.

After March 6, 2001, the majority of the 112 kg/ha of nitrogen fertilizer leached out

of the soil profile because there was a considerable amount of rainfall received by the









field. Another nitrogen fertilizer application of 112 kg/ha, applied on March 24, 2001,

resulted in the total nitrate-nitrogen content in the soil increasing to approximately 335

kg/ha in the top 90 cm on March 24, 2001. After March 24, 2001, the nitrate-nitrogen

content remained relatively constant through April 3, 2001 with a slight decrease due to

the 7.6 cm of applied water and root uptake. The decrease in total nitrate-nitrogen

content was small, likely because the plant canopy had started to reach the maximum leaf

area index (LAI), which reduced the total effective rainfall. The decreased effective

rainfall in decreased infiltration and nitrate-nitrogen leaching. However, during the

period from March 24, 2001 to April 3, 2001, there was still considerable nitrate-nitrogen

movement in the soil profile. In fact, 32.8 kg/ha of nitrate-nitrogen was leached out of

the top 30 cm and into the lower 60 cm with the majority of the leached nitrate-nitrogen

residing at the 60-90 cm depth out of the reach of plant roots.

Starting April 1, 2001, the field was continuously irrigated applying approximately

0.8 cm of water daily. During this period, nitrate-nitrogen was leached out of the soil

rapidly as seen from the soil samples taken on April 20, 2001. Between April 3, 2001

and April 24, 2001, there was a net reduction in nitrate-nitrogen in the soil of 281 kg/ha.

As a result, an additional 34 kg/ha of nitrogen fertilizer was applied on April 28, 2001.

With the continuous irrigation, the nitrate-nitrogen applied to the field on April 28, 2001

was leached out of the soil profile reducing the total nitrate-nitrogen to 83.2 kg/ha on

May 25, 2001. On May 20, 2001, the center pivot was shutdown, herbicides were

applied to the crop to kill the vegetation, and there were no additional nitrogen fertilizer

applications. This would create an environment in which there would be minimal

leaching and no nutrient uptake by the plants. However, there was a substantial increase









in total nitrogen content after May 25, 2001 that can be seen from the data for June 6,

2001. There are a few possibilities that may have contributed to the increased nitrogen

content in the soil. One possibility is that there was an upward flux of soil-water and

nitrate-nitrogen due to the evaporation occurring at the soil surface. But the soils located

at the project site are extremely sandy and are probably self-mulching, which makes it

unlikely that there was upward flux of water and nitrogen. The most probable

explanation is related to the re-bedding of the beds on June 4, 2001 before harvest to

prevent potato decay. During this procedure, the dead plant material was incorporated

into the soil, which could have been mineralized by the soil microorganisms.

Crop monitoring results

Crop monitoring of the spring 2001 potato crop included obtaining information

from the farmer, visual field observations of timing of particular phenological events, and

crop biomass sampling during the growing season. The crop development was well

documented from weekly field visits to the farm over the growing season and information

including planting date, emergence, tuber initiation, maximum LAI, and killed date were

noted (Table 2-5).

Table 2-5. Important dates related to planting, harvest, and phenological events (2001).

Event Date Days After Planting

Planting 02/15/2001 0
Emergence 03/07/2001 20
Tuber Initiation 04/01/2001 45
Anthesis 04/04/2001 49
Maximum LAI 04/20/2001 64
Killed Date 05/21/2001 95
Harvest 06/01/2001 106

The biomass samples were taken 37, 40, 47 and 78 days after planting. Total final

yields based on all the potatoes harvested was 38.7 Mg/ha for the north half and 33.7









Mg/ha for the south half. The biomass samples and the final yield were used to estimate

total nitrogen uptake of the potato crop. The nitrogen concentrations determined from the

plant tissue analysis were multiplied by each plant part and then summed to determine the

total nitrogen mass in each plant sample. The average plant nitrogen mass per plant was

then determined for each sample date and multiplied by the planting density of the entire

field area to determine the nitrogen uptake per unit area. At the time of the final yield

harvest, the vegetative growth had been killed by herbicides, so it was not possible to

measure the final nitrogen uptake. Thus, the final nitrogen uptake was extrapolated using

the plant data collected on May 4, 2001 and June 1, 2001. Leaf and stem weight at the

kill date on May 21, 2001 were assumed to be the same as those on May 4, 2001. Also,

the nitrogen concentrations of stems, leaves, and tuber were assumed to be the same as

those measured from the May 4, 2001 plant samples. The tuber weight measured on June

1, 2001 was used as an estimate of the tuber weight on May 21, 2001. Figure 2-3

compares the total nitrogen uptake to the cumulative nitrogen applied on the north half of

the field. The cumulative nitrogen includes the fertilizer applications plus the nitrogen

that was applied through irrigation due to increased nitrate concentrations (20 mg/L) in

the irrigation well water.

Figure 2-3 indicates that approximately 101.7 kg/ha of the nitrogen applied was

actually recovered by the plants. The field experiments that were conducted provide

valuable knowledge related to nitrogen uptake and leaching for potato crops. Soil

samples indicated that the irrigation applied to the field was more than adequate to

maintain field capacity. Also, soil-water nitrate concentrations show that nitrate-nitrogen

tends to move through the soil profile quickly and out of the zone that plant roots take up












the nitrogen effectively due to the over irrigation of the crop. This was substantiated


from the four biomass harvest taken over the growing season, which indicate that


approximately 30% of the total nitrogen applied was utilized by the crop.


Figure 2-3. North half cumulative nitrogen applied and total crop uptake (2001). Error
bars represent one standard deviation about the mean of the measured values.
No standard deviation was calculated for the final point because point was
extrapolated. Also, error bars are present on the all other samples but cannot
be seen due to the small standard deviations relative to the measured values.


Spring 2002 Potato Crop


Planting details, crop management and weather


The spring 2002 potato crop had similar planting details to those of the spring 2001


potato crop. All the planting information listed in Table 2-2 for the 2001 potato crop are


the same for the 2002 potato crop, except that corn was the previous crop planted and


row spacing was 90 cm. As previously stated, two different management practices were


450

400

350

300
-

25 250
5
o 200
z
150

100 --

50

0
1/1/01


1/15/01 1/29/01 2/12/01 2/26/01 3/12/01 3/26/01 4/9/01 4/23/01 5/7/01 5/21/01
Date

N-Applied Plant Uptake










implemented on the field. The south half received approximately a 21% reduction in

irrigation from that used on the north half and a 12% reduction in nitrogen applied (Table

2-6). The south half irrigation was managed according to weather conditions and crop

status, which was monitored daily by Justin Jones from the University of Florida

Research Center located in Live Oak, FL and Joel Love, a FDACS employee. The

irrigation schedules for the north and south halves of the field are shown in Appendix C.

Weather data were collected weekly from an onsite weather station adjacent to the field,

which include hourly solar radiation, rainfall, and temperature.

Table 2-6. Spring 2002 approximate nitrogen fertilizer schedule and amounts.

Applied
Date Julian Day Nitrogen Fertilizer Type/Application Method
(kg/ha)

North

1/10/2002 10 41 4-10-27, pre-plant in bed
1/15/2002 15 28.5 19-0-0, pre-plant in bed
2/13/2002 44 17 10-34-0, at plant
3/13/2002 72 101.5 19-0-0, sidedress
3/25/2002 84 104 19-0-0, sidedress
South
1/16/2002 16 90.5 19-0-0, in-bed
2/16/2002 47 17 10-34-0, at plant
3/15/2002 74 56 19-0-0, sidedress
3/26/2002 85 97.5 19-0-0, sidedress


U



















i


North half moisture content results

The methods used to monitor vadose zone for the spring 2002 potato crop were

similar to methods discussed previously for the spring 2001 potato crop with a few

modifications in the field methods. Soil samples were taken on a biweekly basis at 10

locations in close proximity to the wells, alternating between the north and south halves

of the field each week. The 10 biweekly sample sets were comprised of five sets of


U



















i










samples taken in the center of the beds and five taken in the center of the furrow. The

additional furrow samples were taken in order to observe the lateral movement of

nitrogen and water between the bed and furrow. The samples were taken at the same

depth increments, 0-15, 15-30, 30-60, and 60-90 cm, as the 2001 soil samples. The

complete set of field measurements and results for spring 2002 potato crop soil samples

are shown in Appendix A. The results for the north half average volumetric moisture

contents of the bed soil samples are shown in Figure 2-4. Refer Table 2-7 for the

standard deviations of the measured values.

1/1/02 1/21/02 2/10/02 3/2/02 3/22/02 4/11/02 5/1/02 5/21/02

1' II 5
6 11 "11 11 11111111111 11 .. 1







14


5
0 20

25


01/01/02 01/21/02 02/10/02 03/02/02 03/22/02 04/11/02 05/01/02 05/21/02
Date



Figure 2-4. North half average volumetric moisture contents for the spring 2002 potato
crop in the center of bed. Total water includes rainfall plus irrigation.

The results shown in Figure 2-4 for the north half moisture contents provide a good

illustration of how the soil tended to remain at or above field capacity in the bed over the

growing season. Even with excessive amounts of water applied to the field, the soils

generally drained to field capacity rapidly. Significant increases in moisture content are

apparent only in instances when the soil samples were taken directly following a large

rainfall event. This is shown in the January 23, 2002, March 7, 2002 and April 17, 2002









soil moisture content results. On January 23, 2002, the moisture content increase is due

to the 4.7 cm of rainfall that occurred on January 21, 2002. The increase in the moisture

contents for the samples taken on March 7, 2002 are a direct result of the 6.9 cm and 6.4

cm of rainfall that occurred on March 3, 2002 and March 4, 2002, respectively. The last

noticeable increase in the moisture contents on April 17, 2002 was caused by the 3.7 cm

of rainfall on April 16, 2002. The soil drained considerably after May 5, 2002, because

there was little rainfall and irrigation was minimal. On May 11, 2002, the pivot was shut

down, so no supplemental water was applied to the field. Thus, this was the cause of the

low moisture contents from the May 15, 2002 soil samples.

Table 2-7. The standard deviations of the 2002 north half measured volumetric moisture
contents.

Standard Deviation (%)
Date
Depth
0-15 cm 15-30 cm 30-60 cm 60-90 cm
01/09/02 0.60 0.25 0.51 0.49
01/23/02 0.32 0.96 1.62 0.46
01/30/02 0.59 0.86 0.91 0.65
02/21/02 1.28 0.39 0.58 0.72
03/07/02 0.58 0.46 0.79 0.38
03/20/02 0.26 0.63 0.45 0.49
04/03/02 0.39 0.91 0.98 0.83
04/17/02 0.92 0.46 0.81 0.92
05/01/02 1.22 0.81 0.80 0.68
05/15/02 1.02 0.84 1.06 0.78
05/29/02 1.99 1.18 0.42 0.56

South half moisture content results

Figure 2-5 shows the results for the south half average volumetric moisture

contents for the bed soil samples. The standard deviations of the measured values for the

south half moisture contents are contained in Table 2-8.











1/1/02 1/21/02 2/10/02 3/2/02 3/22/02 4/11/02 5/1/02 5/21/02

16 I "

14 5

12
100
Io 10



S20-


25
2-20


0 30
01/01/02 01/21/02 02/10/02 03/02/02 03/22/02 04/11/02 05/01/02 05/21/02
Date



Figure 2-5. South half average volumetric moisture contents for the spring 2002 potato
crop in the center of bed. Total water applied includes rainfall and irrigation.

The results from the experiment conducted on the south half of the field gives

valuable insight on how plant water availability was affected by the reduction in the

irrigation applied. During the experiment, there were a few noticeable increases in the

moisture content of the soil. The first two sets of the average moisture content results

shown in Figure 2-5 are identical to those shown in Figure 2-4. The field was still

undergoing preparation for the crop at this time and the plant beds had not been made yet.

So, the cause of the increase in moisture content that was observed from the January 23,

2002 samples are the same as those previously discussed. The high moisture contents

measured from the April 12, 2002 soil samples were caused by 0.1 cm of rainfall

occurring the day of sampling and by prior rainfall events of 1.9 cm on April 10, 2002

and 2.1 cm on April 11, 2002. Besides the soil sample sets collected directly following a

large rainfall event, the majority of the moisture content measurements of the soil

samples generally remained at or slightly above field capacity. The moisture content










results indicate the reduced irrigation applied had very little impact on plant water

availability and shows that the north half of the field was over-irrigated.

Table 2-8. The standard deviations of the 2002 south half measured moisture contents.

Standard Deviation (%)
Date
Depth
0-15 cm 15-30 cm 30-60 cm 60-90 cm
01/09/02 0.66 0.26 0.32 0.57
01/23/02 1.73 0.81 0.68 0.77
02/06/02 0.45 0.96 0.42 0.27
02/27/02 0.78 0.99 1.79 1.30
03/15/02 0.46 0.76 0.57 0.47
03/27/02 1.10 0.41 0.96 0.57
04/12/02 0.13 0.05 2.50 1.75
04/24/02 1.06 0.73 0.58 0.40
05/06/02 1.22 1.91 0.75 0.85
05/22/02 2.68 1.20 1.24 0.95
01/09/02 0.66 0.26 0.32 0.57


North half bed nitrate-nitrogen results

The results from the soil samples taken in the beds also provided information

pertaining to the nitrate-nitrogen transport in the soil profile. The bed soil sample results

for the north half of the field are shown in Figure 2-6. The figure shows the nitrate-

nitrogen movement in the soil over time and the possibility of the nitrogen leaching into

the underlying Floridan Aquifer on the north half of the field. Remember, the plant roots

occupy only the top 30-45 cm and are restricted to the bed only, so any nitrate-nitrogen

below this depth eventually enters the aquifer. At the beginning of the spring 2002 potato

crop season, two pre-plant nitrogen fertilizer applications of 41 kg/ha and 28.5 kg/ha

were applied to the north half of the field on January 10, 2002 and January 15, 2002,

respectively. After the fertilizer applications, there was a noticeable increase in the

nitrate-nitrogen content that is shown in the results from the soil samples taken on

January 23, 2002. The majority of the applied nitrogen had already leached to the 15-30












cm depth in the soil profile due to the 11.8 cm of rainfall that occurred between January


9, 2002 and January 23, 2002.


500
N-Applied
0 N-Applied
4501 H 8OAppled
N-Applied 108cm H20 Applied
41 kg/ha (01/10/02) 4 2 cm
28 5 kg/ha (01/15/02)
400 H20 Applied N-Applied N-Applied N-Applied -
11 8 cm 17 kg/ha (02/13/02) 104 kg/ha (03/25/02) 0
H20O Applied H20 Applied H20 Applied
350 1 2cm 10 8 cm 154cm
N-Applhed
N-Applied 0 N-Applied 0
S300 H20 Applied 101 5 kg/ha -H Applied
2 92cm (03/13/02) 1 9 cm
H20 Applied
250 3 3 cm
S2503
N-Appl.ed
200 o
20H0 Applied
N-appled nitrogen is the total nitrogen applied for the total area. All fertilizer
150 l'o
H2p Apprlied
S14 cm
100




01/09/02 01/23/02 01/30/02 02/21/02 03/07/02 03/20/02 04/03/02 04/17/02 05/01/02 05/15/02 05/29/02 06/12/02
Date
o ,,., ,,. .... M .



Figure 2-6. Average 2002 north half nitrate-nitrogen content in top 90 cm take-nin the
center of bed. Each depth increment is an average of five samples. The

applied nitrogen is the total nitrogen applied for the total area. All fertilizer
application dates are approximate.


After January 23, 2002, the nitrate-nitrogen continued to be leached out of the soil


profile, which decreased the amount ofnitrate-nitrogen in the top 30 cm. This is shown


in the January 30, 2002 soil sample results. There was a slight increase in the total


average nitrate-nitrogen content at 30-90 cm, but the majority of the nitrate-nitrogen had


already leached out of the soil profile by this time. Another nitrogen fertilizer application


of 17 kg/ha was applied on February 13, 2002 and the soil samples taken on February 21,


2002 display an 11.5 kg/ha increase in the nitrate-nitrogen content at 0-15 cm. However,


considerable leaching still occurred over this period. The nitrate-nitrogen that was


observed at the 30-60 cm depth on January 30, 2002 had leached out of the soil profile by









February 21, 2002. The north half of the field had received large amounts of total applied

water between February 21, 2002 and March 7, 2002, which reduced the average total

nitrogen content to 43.9 kg/ha by March 7, 2003.

On March 13, 2002, 101.5 kg/ha of nitrogen fertilizer was applied to the field,

which was around the time of crop emergence. The fertilizer increased the nitrate-

nitrogen amount at 0-15 cm to approximately 119 kg/ha, which is shown in the results

from the soil samples taken on March 20, 2002. Small increases in the nitrate-nitrogen

content were observed at lower depths due to the leaching from the upper 0-15 cm that

occurred from the 3.3 cm of total water received. After March 20, 2002, the majority of

the nitrate-nitrogen in the soil leached out of the top 90 cm. This was evident after

examining the results for the soil samples taken on April 3, 2002. Between March 20,

2002 and April 4, 2002, there was an additional nitrogen fertilizer application on March

25, 2003. The fertilizer application had little affect on the total average nitrate-nitrogen

content in the top 90 cm of the soil profile according to the April 4, 2002 soil results.

Approximately 25% of the nitrogen that was located in the top 30 cm on March 20, 2002

was taken up by the potato plants by April 4, 2002 (Figure 2-10), which left the majority

of the nitrate-nitrogen to be leached out of the soil profile by the 3.1 cm of irrigation

applied from March 20, 2002 through March 24, 2002. The nitrate-nitrogen then

increased on March 25, 2002 as a result of the 104 kg/ha of nitrogen fertilizer applied on

that day, which explains why the total average nitrate contents for March 20, 2002 and

April 4, 2002 are virtually the same. Leaching occurred over the next 10 days following

the fertilizer application, which is shown in the April 17, 2002 soil sample results. The

majority of the applied fertilizer was leached out of the top 15 cm and into the lower 60










cm of the soil profile. However, the majority of the nitrate-nitrogen remained in the top

90 cm of the soil because the crop canopy was starting to develop, which reduced the

infiltration.

There were no additional fertilizer applications after March 25, 2002. However,

the May 1, 2002 results show that there was a dramatic increase in nitrate-nitrogen

content, which exceeded all previous measurements. The data from the soil samples

taken on May 1, 2002 have significant variations in the measured values for each depth

increment, especially for the samples taken in close proximity to observation wells 9 and

10 (Table 2-9), which were the cause for the anomaly.

Table 2-9. Nitrate-nitrogen content results for north soil samples taken on May 1, 2002
for wells.

Well Depth Average (kg/ha)
(cm)
0-15 8.67
15-30 8.25
30-60 10.27
60-90 15.10
0-15 42.87
15-30 215.06
30-60 361.32
60-90 206.52
0-15 39.50
15-30 450.35
30-60 45.47
60-90 270.50
0-15 10.63
15-30 85.89
30-60 69.24
60-90 45.69
0-15 5.40
15-30 107.86
30-60 45.87
60-90 99.11


The center pivot was shutdown on May 13, 2002 and the plants were killed with

herbicide on May 17, 2002. Following May 1, 2002, the nitrate-nitrogen content

decreased due to leaching. As in 2001, there are some noticeable increases in the nitrate-

nitrogen content in the top 15 cm of the soil profile that were observed from the May 29,











2002 and June 12, 2002 samples. The increased nitrate-nitrogen contents were most


likely caused by the mineralization of the dead plant material that was incorporated into


the soil at re-bedding.


South half bed nitrate-nitrogen results

The bed soil sample results for the south half of the field are shown in Figure 2-7.


Figure 2-7. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the
center of bed. Each depth increment is an average of five samples. The
applied nitrogen is the total nitrogen applied for the total area. All fertilizer
application dates are approximate.


The bed soil samples results provide evidence that the reduced nitrogen fertilizer


and irrigation applied to the south half of the field reduced the rate and quantity of


nitrate-nitrogen leached out of the vadose zone (Figure 2-7). In the beginning of spring


2002, 90.5 kg/ha of pre-plant nitrogen fertilizer was applied to the south half of the potato


500

450

400

350

S300

S250

2 200
z
150

100

50


01/09/02 01/23/02 02/06/02 02/27/02 03/15/02 03/27/02 04/12/02 04/24/02 05/06/02 05/22/02
Date
,:,,-?,,i r :,:, .,:, r 1:.: r I :, i: r,


06/05/02









field. The applied fertilizer resulted in an increase in nitrate-nitrogen in the top 30 cm of

the soil profile, which can be seen from the January 23, 2002 soil sample results.

After January 23, 2002, the south half of the field received 3 cm of water, which

leached approximately half of the nitrate-nitrogen out of the top 30 cm of the soil profile.

Some of the leached nitrate-nitrogen was retained in the bottom 60 cm, but approximately

40 kg/ha was leached of the soil profile. A slight increase in total average nitrate-

nitrogen content on February 27, 2002 was observed, which was caused by the 17 kg/ha

of nitrogen fertilizer applied on February 16, 2002. The subsequent soil samples taken on

March 15, 2002 indicated that there was a substantial amount of nitrate-nitrogen leached

out of the soil profile, which can be attributed to the 14.2 cm of rainfall and 1.4 cm of

irrigation applied from February 27, 2002 through March 15, 2002. It appeared that there

was no significant leaching of nitrate-nitrogen from 0-15 cm depth according to the soil

samples results taken on March 15, 2002, but the sustained nitrate-nitrogen concentration

can be attributed to the 56 kg/ha of nitrogen fertilizer applied on that day.

A large increase in nitrate-nitrogen content was noticed on March 27, 2002 for the

top 30 cm, which was a result the 97.5 kg/ha of nitrogen fertilizer applied the day before.

The results obtained on April 12, 2002 indicated that the 6.3 cm of rainfall and 9.9 cm of

irrigation applied between March 27, 2002 and April 12, 2002 reduced the nitrate-

nitrogen content in the top 15 cm to 26 kg/ha. Most of the nitrate-nitrogen lost from the

top 15 cm was retained in the 15-30 cm depth of the soil profile. The amount leached

was not as dramatic as that seen on March 15, 2002, because the crop had begun to

develop good canopy cover. As previously discussed, the plant canopy reduced the

effective water applied to the beds, which reduced the infiltration and nitrate-nitrogen









leached. An additional 9.9 cm of water was applied to the south half of the field from

April 12, 2002 through April 4, 2002. This resulted in approximately half of the nitrate-

nitrogen in the top 30 cm being leached into the bottom 60 cm of the soil profile.

Senescence started to occur after April 24, 2002, which led to the large majority of

the nitrate-nitrogen being leached out of the soil profile by the 7.8 cm of water applied

between April 24, 2002 and May 6, 2002. The center pivot was shutdown on May 13,

2002 and the potato crop was killed by herbicides on May 18, 2002. There were

noticeable increases in nitrate-nitrogen content in the top 30 cm observed from the soil

samples taken on May 22, 2002 and June 6, 2002, which were most likely caused by

mineralization of dead plant material incorporated in the bed at re-bedding.

North half furrow nitrate-nitrogen results

Originally, it was assumed that the nitrogen transport in the soil was one-

dimensional with the transport of the nitrogen fertilizer being restricted to the bed,

because the fertilizer was band-applied to the crop. However, no data had been taken in

the furrow prior to this experiment to substantiate this hypothesis. The results from the

samples taken in the furrows for the north half are shown in Figure 2-8. Note that nitrate-

nitrogen content results for the furrow soil samples are an order of magnitude smaller

than that measured for the bed samples.

As shown Figure 2-8, the nitrate-nitrogen content in the furrow tends to remain

stable throughout the growing season. The only source of the nitrate-nitrogen in the

furrows was from the irrigation water due to the elevated nitrate-nitrogen concentrations

in the irrigation well water. Most of the measured values tended to range between 5

kg/ha to about 16 kg/ha for the both the north and south halves of the field with no

noticeable increases in nitrate-nitrogen content following fertilizer applications. For











example, on March 13, 2002 there was a side-dressed nitrogen fertilizer application of


101.5 kg/ha on the north half of the field and the results from the March 20, 2002 furrow


soil samples for the soil nitrate-nitrogen content showed that the nitrate-nitrogen content


in the furrow remained at about 15 kg/ha. However, there are some noticeable increases


in average nitrate-nitrogen content for the north half of the field observed on February 21,


2002, May 1, 2002, and May 29, 2002.


N-Applied N-Applied
H2OApplied H2OApplied
35 N-Applied 108cm 4 2 cm
101 5 kg/ha (03/13/02)
N-Applied H20 Applied N-Applied
17 kg/ha (02/13/02) 33cm 0
H20 Applied H20 Applied
30 12 cm 15 4 cm N-Applhed
mN-Ap pled H20 Applied




10
d n n i Applhed N-pplied
S25 148cm 104 kgha (03125102)
H2applicatn d s ae Appled

2 20










01/30/02 02/21/02 03/07/02 03/20/02 04/03/02 04/17/02 05/01/02 05/15/02 05/29/02
Date




Figure 2-8. Average 2002 north half nitrate-nitrogen content in top 90 cm taken in the
center of furrow. Each depth increment is an average of five samples. The
applied nitrogen is the total nitrogen applied for the total area. All fertilizer
application dates are approximate.

South half furrow nitrate-nitrogen results

Similar discrepancies were observed in the furrow soil samples taken on the south


half of the field (Figure 2-9) on February 27, 2002 and June 5, 2002. But for the majority


of the results, there were no noticeable increases in nitrate-nitrogen content over the


growing season or following fertilizer applications. The south half of the field received












two side-dressed nitrogen fertilizer applications on March 15, 2002 and March 26, 2002


of 56 kg/ha and 97.5 kg/ha, respectively. Results from the south half furrow soil samples


taken on March 27, 2002 showed that there was little change in the nitrate-nitrogen


content in the soil.



N-Applped
N-Applied 0
N-Appled 56 kg/ha (03/15/02) N-Applied H20 Applied
0 97 5 kg/ha (03126102) 0 N-Applied 1 2 cm
N-Applied H 0 Applied H20 Applied H20 Applied
25 17 kg/ha (02/16/02) 156c 41cm 99 cm HO Appied
H20 Applied 3 1 cm
20 cm
N-Applied N-Applied
0 0
20 1 H0 ApplIed H20 Applied
1 21 cm 78cm


2 15



10



5-




02/06/02 02/27/02 03/15/02 03/27/02 04/12/02 04/24/02 05/06/02 05/22/02 06/05/02
Date




Figure 2-9. Average 2002 south half nitrate-nitrogen content in top 90 cm taken in the
center of furrow. Each of the depth increments is an average of five samples.
The applied nitrogen is the total nitrogen applied for the total area. All
fertilizer application dates are approximate.


The results shown in Figures 2-8 and 2-9 show that the nitrate nitrogen in the


furrow tended to remain fairly constant for the entire field during most the growing


season, but reasons for the relatively high nitrate-nitrogen contents were not clear. After


further examination of the analysis results for the furrow soil samples that showed


increased nitrate-nitrogen content, it was obvious that there were substantial deviations in


the measured values. These relatively high deviations in the measured values for several


soil sample depths indicated spatial variabilities in the nitrate-nitrogen measurements.










Table 2-10 contains the results from the statistical analysis of the data taken on those

dates.

Table 2-10. Statistical analysis of spring 2002 furrow soil samples nitrate-nitrogen
results.

Dae Haf Depth Average Maximum Minimum Standard Deviation
(cm) (kg/ha) (kg/ha) (kg/ha) (kg/ha)

0-15 9.3 14.4 3.6 4.5
/2/0 15-30 3.1 5.4 1.2 1.7
02/21/02 N
30-60 2.5 3.7 1.5 0.9
60-90 11.7 48.3 1.5 20.4
0-15 10.7 25.0 5.0 8.3
15-30 6.1 9.1 3.9 2.0
02/27/02 S
30-60 3.2 3.8 2.7 0.5
60-90 1.7 2.5 0.9 0.6
0-15 9.3 17.1 5.2 4.9
15-30 6.5 13.4 2.9 4.7
05/01/02 N
30-60 11.2 21.7 5.9 6.6
60-90 9.9 18.4 5.6 5.8
0-15 7.7 26.2 2.1 10.4
15-30 4.3 8.4 1.3 3.1
05/29/02 N
30-60 4.6 7.6 2.8 1.9
60-90 2.6 4.1 1.5 0.9
0-15 11.3 14.7 7.7 2.9
15-30 5.7 8.7 3.6 1.9
06/05/02 S
30-60 4.3 6.8 3.0 1.4
60-90 3.5 5.2 2.5 1.0


As shown in the Table 2-10, several of the layers had large variability in the

measured values. For example, the samples taken on February 21, 2002 had significant

variation between the maximum and minimum measured values in the nitrate-nitrogen

contents for the soil samples taken at 60-90 cm. The maximum value was measured to be

48.3 kg/ha, which is relatively high when compared to the minimum value of 1.5 kg/ha.

This accounts for the high average value of 11.7 kg/ha. When the maximum value is not

included in the average for the 60-90 cm depth, a more reasonable average nitrate-

nitrogen content of 2.6 kg/ha was obtained.









In the soil samples taken on February 27, 2002, there was significant variation

(coefficient of variation = 0.78) in the measured values for the samples taken at 0-15 cm.

The majority of the samples varied from approximately 5.0 kg/ha to 6.5 kg/ha for the

nitrate-nitrogen content, but there were two relatively high measured values of 10.5 and

25 kg/ha. The May 1, 2002 samples had a few discrepancies in the measured nitrate-

nitrogen contents for all of the sample depths. The 0-15 cm samples had two large

measured values of 11.4 and 17.1 kg/ha, while the remaining three samples had an

average nitrate-nitrogen content of 6.0 kg/ha.

The samples taken at 15-30 cm had two high measured values of 9.6 and 13.4

kg/ha, while the other measured values ranged from 2.9 to 3.8 kg/ha for nitrate-nitrogen.

Two relatively high nitrate-nitrogen contents of 13.7 and 21.7 kg/ha were measured from

the 30-60 cm samples. The three other samples taken at 30-60 cm averaged out to be

approximately 7.0 kg/ha for nitrate-nitrogen. The 60-90 cm samples had two measured

values of 18.4 and 13.2 kg/ha for the nitrate-nitrogen content. These two measured

values are relatively high when compared to the three other soil sample measurements

that ranged from 5.7 to 6.3 kg/ha for nitrate-nitrogen.

There was slightly less variation in the measured nitrate-nitrogen contents for the

samples taken on May 29, 2002. The average measured value was slightly higher than

expected. Only one nitrate-nitrogen measurement of 26.2 kg/ha at 0-15 cm was

significantly higher relative to the other sample measurements, whose values ranged from

2.4 kg/ha to 5.3 kg/ha for nitrate nitrogen. The high average nitrate-nitrogen content

measured from the soil samples taken on June 6, 2002 can be attributed to variations in

the measured values for all of the sample depths. There were no substantial deviations in









the measured values, but there were noticeable increases for the measurements taken at

each depth interval. After the analysis of these sample results, it was clear that

measurement error was the likely cause of the high average total nitrate nitrogen content

on the previously mentioned dates and that nitrate-nitrogen transport of the fertilizer was

restricted to the bed.

Crop monitoring

As previously discussed, crop monitoring for the spring 2002 potato crop consisted

of obtaining information from the farmer, visual field observations of timing of certain

phenological events, and crop biomass sampling during the growing season. The crop

development was documented from weekly visits to the farm (Table 2-11).

Table 2-11. Important dates related to planting, harvest, and phenological events (2002).

Event Date Days After Planting
North South North South
Planting 02/12/02 02/15/02 0 0
Emergence 03/10/02 03/10/02 20 23
Tuber Initiation 04/01/02 04/01/02 42 45
Anthesis 04/01/02 04/01/02 42 45
Maximum LAI 04/20/02 04/20/02 61 64
Killed Date 05/17/02 05/18/02 91 92
Harvest 05/24/02 05/24/02 98 98
Biomass samples for the north half of the field were taken at 47, 68, and 80 days

after planting. The biomass samples for the south half were taken at the same times as

those listed for the north half, except for the first set of samples. The first biomass

harvest taken for the south half was done at 56 days after planting. Total final yields

based on all the potatoes harvested was 36.5 Mg/ha for the north half and 36.0 Mg/ha for

the south half.

The three biomass samples and final tuber yield were used to estimate total

nitrogen uptake of the potato crop. The methods used to determine nitrogen uptake are









identical to those previously discussed for the 2001 potato crop. The estimates calculated

for the total nitrogen uptake provided critical information regarding the effectiveness of

the reduced nitrogen and irrigation applied. Figure 2-10 compares the cumulative

nitrogen applied to the total plant nitrogen uptake for the north and south halves of the

field. The cumulative nitrogen includes the fertilizer applications shown in Table 2-6

plus nitrogen applied through the irrigation applied due to elevated nitrate-nitrogen

concentrations (10 mg/L) of the irrigation well water.

Figure 2-10 provides insight on how fertilizer and irrigation scheduling can be

modified in order to reduce nitrate-nitrogen leaching. This figure indicates that the potato

plants on the north half of the field recovered 155 kg/ha of the total 364 kg/ha of nitrogen

applied from the fertilizer applications and the irrigation, which is a 42% recovery of

nitrogen. This was a major improvement from the 30% that was recovered during the

2001 season. The south half plants recovered 132.2 kg/ha of the total 316 kg/ha of

nitrogen applied, which is also a 42% recovery of nitrogen. However, it is clear from the

soil sample results that nitrogen was more readily available for crop uptake over the

entire growing season on the south half of the field and that the lower irrigation reduced

the rate that nitrogen leached out of the top 30 cm. More nitrogen was taken up on the

north half despite that nitrogen was more readily available to the south half plants. This

was mostly likely due to the differences in the planting dates (Table 2-11). The north

half plants were planted earlier, so were able to take up nitrogen for a longer period of

time. Also, there may have been some error in the extrapolated final dry tuber yield

estimate because there were no nitrogen concentration measurements of the tubers, stems,

and leaves at final harvest. The soil moisture results also show that the north half of the











field was still being over irrigated, which resulted in the nitrogen quickly leaching out of


the top 30 cm of the soil profile.


400

350

300

250

5o ---------------------------------------------
S200

150

100

50


1/1/02 1/11/02 1/21/02 1/31/02 2/10/02 2/20/02 3/2/02 3/12/02 3/22/02 4/1/02 4/11/02 4/21/02 5/1/02 5/11/02
Date





Figure 2-10. Nitrogen applied and total crop uptake (2002). Error bars represent one
standard deviation about the mean of the measured values. No standard
deviation was calculated for the final point because point was extrapolated.

Comparisons of Final Yield/Nitrogen Lost and Nitrogen Applied

Figures 2-11 and 2-12 show the general trend in the dry tuber yield and nitrogen


lost in relation to total nitrogen applied. The data shown include information for all four


treatments that were implemented during the 2001 and 2002 growing seasons. Note that


the nitrogen applied is comprised of the fertilizer applications plus the nitrogen applied


through the irrigation due to the elevated nitrate-nitrogen concentrations in the irrigation


well water.


















6000 A
*I0


0 50 100 150 200 250 300
Nitrogen Applied (kg/ha)
0 I < ll : .,n-ir. "i'. Alll in .'.- O S n- ",i .-


350 400 450


Figure 2-11.


Comparison between the total nitrogen applied and the dry tuber yield.


0 50 100 150 200 250 300
Nitrogen Applied (kg/ha)
l1:,1r, : .', I : : Ajil. -,:, I A ll:.1r. -,:, ," _:,Ir. ",:,:"


350 400 450


Figure 2-12. Comparison between the total nitrogen applied and the nitrogen lost


Figure 2-11 illustrates how the dry tuber yield is affected by the total amount of


nitrogen applied over the growing season. The figure indicates that the yield usually


increases with increasing fertilizer applications amounts. However, the results in the


figure show that the yields are generally stable for the nitrogen fertilizer amounts applied


during 2001 and 2002 growing season. As shown in Figure 2-11, the dry tuber yield


*


________________________________A


_____________________________________A______0









ranges from 5,684 kg/ha for the south half of the field in 2002 to 6,840 kg/ha in 2001 for

the north half of the field. The yield stability indicates that there is specific amount of

nitrogen fertilizer that can be applied to the crop that will produce the maximum yield,

and any additional fertilizer applied will result in negligible increases in dry tuber yield.

Unlike the dry tuber yield, the nitrogen lost depends significantly on the amount of

nitrogen applied. Figure 2-12 shows that as the nitrogen fertilizer application increases

the amount nitrogen lost also increases. In 2001, 427 kg/ha of nitrogen fertilizer was

applied to the north half of the field and 325.3 kg/ha was lost. On the south half of the

field, the fertilizer applied was reduced to 394 kg/ha, which resulted in 310.3 kg/ha being

lost. The nitrogen fertilizer applied in 2002 was lower than that applied in 2001. The

total applied nitrogen to the north and south halves of the field was 364 kg/ha and 316

kg/ha, respectively. With the reduced fertilizer application amounts, the nitrogen lost

was 208.5 kg/ha and 183.8 kg/ha for the north and south halves of the field, respectively,

which is somewhat lower than that lost in 2001. This indicates that acceptable yields can

be achieved at the project site with substantial reductions in nitrogen fertilizer amounts

while still maintaining acceptable yields.














CHAPTER 3
MODEL DESCRIPTION AND RESULTS

An existing crop model was used to predict crop yield and nitrate-nitrogen

transport for the spring 2001 and 2002 potato crops that were monitored at the project

site. The primary goal was to properly calibrate the model using the data collected during

the two growing seasons in order to accurately represent the potato crop system. The

Decision Support System for Agrotechnology Transfer (DSSAT) Version 3.5 was the

model used in the analysis of the potato crops. DSSAT is a product of the International

Benchmark Sites for Network for Agrotechnololgy Transfer (IBSNAT) project and is

well known throughout the world. The model was chosen because of its ability to

accurately predict crop yield and nutrient uptake.

DSSAT Model Description

DSSAT is a shell that utilizes a collection of crop models in order to perform crop

growth simulations. The primary use of the shell is to allow the user to enter, store, and

retrieve information necessary for crop simulations, sensitivity analyses, model

calibrations, and model validations. The DSSAT model simulates plant development

based on plant processes, which are directly affected by interactions with the

environment. Also, the model contains a graphical interface that permits the user to

analyze and view model results. The graphical user interface can also be used to navigate

between the various programs and models contained within DSSAT. The crop models

contained in DSSAT include the CERES model (Tsuji et al., 1998 pp. 78-98)for grains,

the CROPGRO model (Tsuji et al., 1998 pp. 99-128) for legumes, and the SUBSTOR









model (Griffin, 1993) for potatoes. The SUBSTOR model was the only model used in

the research conducted. All the models in DSSAT use the same nutrient transport and

hydrologic routines and differ only in the methods used for plant growth. Also, DSSAT

is able to perform both seasonal and sequence analyses. Seasonal analysis relates to the

temporal variability of weather within the growing season and from year to year.

Sequence analysis allows the user to examine the behavior of the crop system over time.

The minimum data required to run the crop model include a weather file, a soil file, a

cultivar file, and a control file (FILEX). Weather data that is used by DSSAT includes

measured data or stochastically generated data that is based on historic weather. The soil

file contains various parameters and information that include porosity, drained upper

limit, soil family, etc. for specific site locations and soil types. The crop file includes

genetic coefficients that affect plant development. FILEX contains information regarding

management practices and references the executable file to the correct soil, weather, and

crop files.

The following is a brief model description of the DSSAT model. For a more

detailed description of the methods used in the DSSAT model including equations, input

file structure, etc, refer to Tsuji (1994) and Tsuji (1998). Also, the input files used in the

crop growth simulations are shown in Appendix C.

Hydrology Component

The soil-water balance routines implemented in DSSAT are described by Ritchie

(Tsuji et al., 1998 pp. 41-54) and are used to predict the vertical one-dimensional soil-

water transport under variably saturated conditions within the soil profile. The soil-water

budget is determined daily and predicts plant transpiration, root water adsorption, soil

evaporation, runoff, infiltration, and drainage.









Runoff and infiltration are determined using the USDA-Soil Conservation Service

(SCS) curve number (CN) with a modification for layered soils. The antecedent moisture

condition used to determine the CN is based on the moisture content in the top layer of

soil. Runoff is calculated using the daily rainfall only, because it is assumed that

irrigation does not affect runoff. The infiltration is defined as the difference between the

total water applied (precipitation plus irrigation) and runoff.

In order to determine the soil-water transport, the soil profile is divided into layers.

When infiltration occurs, drainage is calculated using a cascading method that predicts

the soil-water movement from one soil layer to the next. Drainage only occurs when the

moisture content in a layer exceeds the drained upper limit (DUL). The volume of water

that can drain out of a specified layer is the difference between the current moisture

content and the DUL. The drainage is then calculated using a proportionality constant,

which transports the water into the underlying layer. The volume of water drained from a

layer in a day is dependent on the volume of water above the DUL. If the soil-water flux

entering the soil layer exceeds the volume it can hold (saturated moisture content minus

current moisture content), the excess water is moved into the lower layer.

The potential evapotranspiration (PET) is calculated using a modified Priestly-

Taylor (1972) equation. Parameters needed for the calculation include total daily solar

radiation, maximum temperature, and minimum temperature. The calculated PET is then

separated into potential evaporation and transpiration in order to determine the actual soil

evaporation and actual plant transpiration. During evaporation, an upward water flux is

calculated for the top four soil layers using a soil-water diffusivity function.









Actual root water uptake is determined from the potential uptake per root length.

Reduction factors are used to account for nonideal soil moisture content conditions. The

uptake does not exceed the maximum daily uptake that is assumed to be 0.03 cm3 of

water per cm of root.

Nitrogen Component

The nitrogen balance routines used by DSSAT estimate the nitrogen

transformations, nitrate transport in the soil profile, and nitrogen uptake by plants. The

nitrogen transformation routines include denitrification under anaerobic conditions,

mineralization of organic nitrogen, and nitrification of ammonium. The model can also

predict the transport of nitrogen in the soil profile. Urea and nitrate are assumed to be

mobile in the soil profile, while organic nitrogen and ammonium are considered to be

immobile. Also, the model assumes that the nitrogen located in a specific layer is

uniformly distributed in the layer.

The organic nitrogen is divided into humic material and organic matter. The

organic matter is then separated into carbohydrates, cellulose, and lignin. Each type of

organic matter is assigned a distinct decay constant that corresponds to maximum decay

under non-limiting conditions. Factors that limit the decomposition of organic matter,

which include moisture content, soil temperature, and the effect of the carbon/nitrogen

ratio of the soils, are all accounted for in the decay calculations. The decomposition of

humic material into inorganic nitrogen is calculated in a similar manner to the decay of

organic matter, except the reactions occurs at a much slower rate and carbon/nitrogen of

the soils is not taken into account.

The nitrification of ammonium to nitrate is calculated using a potential nitrification

rate that is based on the Michaelis-Menton kinetic function. This nitrification calculation









method is independent of soil type and depends only on the ammonium concentration.

Factors that reduce the nitrification rate, including temperature, soil moisture content, and

soil ammonium concentration, are taken into account using an environmental limit on

nitrification capacity that ranges from zero to one.

Advection is the only mechanism considered in nitrate transport. As a result,

nitrogen transport in the soil profile from layer to layer is only dependent on the soil-

water transport calculated in the hydrology routines. The equations used to determine

nitrate transport assume that the entire nitrate in the soil is in aqueous form.

Ammonium and nitrate are the two nitrogen forms that are taken up to meet the

nitrogen requirements of the plant. The nitrogen uptake from the soil is dependent on the

amount of nitrogen in the soil and the demand by the plant. The plant demand for

nitrogen is a function of the top weight, concentration of nitrogen currently in the vines,

and the critical nitrogen concentration, which is the minimum amount of nitrogen

required for maximum growth. The actual crop nitrogen uptake is affected by the soil

moisture content, root length density, and nitrogen concentration in the soil solution. To

account for moisture content, a soil water factor that ranges from zero to one is

introduced that reduces the nitrogen uptake potential. Two additional reduction factors

are then determined based on the ammonium and nitrate concentrations. Finally, the root

length density factor is calculated to determine actual plant nitrate and ammonium

uptake.

Crop Growth Component

During this study, the SUBSTOR-Potato Version 2.0 crop model was used to

simulate the biomass accumulation and phenological development of the spring 2001 and

2002 Red LaSoda potato crops based on the soils, weather, and different management









practices used at the project site. The SUBSTOR-Potato Version 2.0 was developed with

the intent to be used over a wide range of geographical locations and for different

cultivars. The inputs used in the potato growth simulation are retrieved from the weather

file, soil file, cultivar file, and a temporary file made from the FILEX created by DSSAT.

The temporary file is created by DSSAT so that the input file is converted to the format

used by SUSTOR. The cultivar file includes five genetic coefficients that characterize

crop growth and development. The five genetic coefficients located in the cultivar file

include the leaf expansion rate (G2), tuber growth rate (G3), determinacy (PD),

temperature (P2), and sensitivity of tuber initiation to photoperiod (TC). There are also

several other crop growth parameters and coefficients that are located in the SUBSTOR

code and species file that are species specific and should not be modified by the

unknowledgeable user. Due to the large number of these parameters and coefficients,

they are not listed here (refer to Griffin et al., 1993). The SUBSTOR outputs include

daily dry matter weights of the leaves, stems, tubers, and roots; daily leaf area index (leaf

area per horizontal ground surface area); and the phenological growth stage.

The simulation of crop development and growth is divided into five stages in

SUBSTOR, which include pre-planting, planting to sprout germination, sprout

germination to emergence, emergence to tuber initiation, and tuber initiation to maturity.

In SUBSTOR-Potato model, the partitioning and accumulation of biomass during the

computer simulation for the leaves, stems, tubers, and roots are dependent on the growth

stage of the crop. Also, growth restrictions caused by high/low temperatures, long

photoperiods, water stresses, and nitrogen stresses are all accounted for in the model.









Model Calibration and Results

In the original DSSAT simulation, Albert (2002) assumed that the computer

simulation was restricted to the bed only. As a result, Albert doubled the fertilizer

applications in the input file because it was presumed that this would be an appropriate

method to concentrate the nitrogen fertilizer in the bed. After further examination of the

source code and consultations with model developers, it was determined that DSSAT

simulates plant growth for the entire row rather than just the bed.

Because of the inconsistencies in Albert's (2002) approach for the spring 2001

potato crop growth simulations, the north half of the field that used the farmer's typical

management practices was re-simulated using a modified FILEX with the correct

fertilizer amounts. All the previous soils data (i.e. CN, porosity, DUL, etc.) and plant

generic coefficients (G2, G3, PD, P2, TC) were used in the new simulation. During the

spring 2001 potato crop, soil sampling did not begin until March 2, 2001, which was well

past the time of the pre-plant fertilizer application and planting. As a result, the initial

conditions for soil moisture content were set equal to the measurements taken from the

March 2, 2001 soil samples and initial nitrogen content was estimated. The initial

nitrogen content measured on January 9, 2002 soil samples were used as initial nitrogen

content for the 2001 simulation. In order to minimize effect of errors in initial

conditions, the simulation was started on January 1, 2001, which was well before the first

fertilizer application on January 18, 2001. The calibration of the model consisted of

comparisons between the measured and simulated values for each sampling depth

described in Chapter 2.

The calibration comprised first adjusting the soil parameters in order to accurately

represent the soil-water conditions in the soil profile. Initially, it appeared that the soil









parameters needed no further adjustments from the values used by Albert (2002). This

was concluded from the comparisons between the measured and predicted results shown

in Figures 3-1 through 3-4. Note that the DSSAT simulation predictions illustrated in the

figures represent weighted averages of the results for each soil layer listed in the output

file in relation to the actual measurement depths. Also, remember that the DSSAT

predictions were calculated daily, so the results represent the daily averages.

The moisture content results for the corrected computer simulation displayed the

same general trends as Albert's (2002) simulation. There were slight differences in the

initial soil moisture content predictions because of the differences in the initial conditions

used in each simulation. For example, at 0-15 cm the corrected model predicted the

moisture content to 0.068 on January 7, 2001, while in Albert's (2002) simulation it was

predicted to be 0.069. But in general, the moisture content predictions for the corrected

simulation and Albert's simulation were virtually the same.

The results indicate that the majority of the simulated values fairly accurately

predicted the measured values. Most of the soil moisture predictions remained within

one standard deviation of the measured values with the majority of the model predictions

being greater than the measured values. The soil moisture predictions displayed very

little variation over the growing season, except for the simulation results at 0-15 cm

depth. The model predictions at 0-15 cm exhibited noticeable increases in the moisture

content following every irrigation application and/or rainfall event. This was caused by

the soil surface exposure to irrigation, rainfall, and evapotranspiration. Also, the

magnitude of the increase depended on the amount of water applied to the field and the

previous moisture content of the soil layer. For example, on January 20, 2001 there was











a 7 mm rainfall event that resulted the simulated moisture contents to increase from 7.6%


on January 19, 2001 to approximately 9% on January 20, 2001. The largest predicted


moisture content observed occurred on March 16, 2001. Prior to March 16, 2001, the


field received 4.5 cm of water from March 14, 2001 through March 18, 2001, which


caused the predicted moisture content to increase from 8% on March 14, 2001 to almost


20% on March 18, 2001.


The simulation results at 0-15 cm also provide valuable information of the soils


ability to drain to field capacity relatively quickly, which is shown in the simulated


moisture content results for March 24, 2001. By March 24, 2001, the moisture content of


the top 15 cm reduced from the 20 to 8%. The decrease may be attributed to the


evapotranspiration and drainage that occurred. The 4.5 cm of applied water also had


significant impacts on the predicted moisture contents for the lower soil depths.





1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
025 0


020 120



Dat
030
2 0100
me '



0 05 80
90
000 100
1/1/01 1/21/01 2/10/01 3/2/01 3/22101 4/11/01 5/1/01 5/21/01
Date



Figure 3-1. DSSAT spring 2001 potato crop soil moisture content results for the north
half at 0-15 cm. Error bars represent one standard deviation about the
measured mean.


















1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01






02 20 E0
E E

h 015 30
0





005 50





Date




Figure 3-2. DSSAT spring 2001 potato crop soil moisture content results for the north

half at 15-30 cm. Error bars represent one standard deviation about the

measured mean.


1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
02 0

018 I I'I" "I''''''' Ir'''T''''''-''' 10

016
0 1 6 1---------------- 1 0-- L -----------------
20
E 014
E E
012 30

01
0 40 ~
008
50 _
006

004 60

002
70

1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
Date





Figure 3-3. DSSAT spring 2001 potato crop soil moisture content results for the north

half at 30-60 cm. Error bars represent one standard deviation about the

measured mean.







57






1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
01 0

014 10

012 20

E ol1 E
u 30
O .
008 -
0 40
006
50 2
0
60
002
70

1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
Time
I T II1 ar=, 1, I.I= ,,, 1 -1- I=' "l..I I


Figure 3-4. DSSAT spring 2001 potato crop soil moisture content results for the north
half at 60-90 cm. Error bars represent one standard deviation about the
measured mean.


As expected, the maximum simulated moisture content also occurred on March 18,


2001 for the lower depths of 15-30, 30-60, and 60-90. After March 18, 2001, the


predicted moisture contents for the lower layers remained relatively stable, but were


slightly higher than the moisture contents predicted earlier in the season by 1-2%. The


elevated moisture contents were caused by the daily 0.8 cm irrigation applications that


began around April 1, 2001.


Figure 3-5 shows the results for the water balance for the entire simulation period.


No runoff was predicted during the entire simulation period. As a result, the total 71.5


cm of water received by the field was infiltrated into the soil surface. Fifty-four percent


of the 71.5 cm water received by the north half of the field was lost by soil evaporation.


Only 6.1 cm of water was taken up by the plant from the soil, while 21.8 cm was lost to


deep drainage.







58


Like the moisture content results, the water balance results for the corrected


simulation compared relatively well to Albert's (2002) simulation. Approximately the


same amount of drainage was predicted in both simulations. However, more


transpiration and evaporation occurred during Albert's simulation. In Albert's


simulation, the transpiration and evaporation was predicted to be 11 cm and 48 cm,


respectively. The differences in the water balances were mostly likely caused by


differences in crop growth for each computer simulation.


80

70

60

50

40

30

20




1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
Date



Figure 3-5. Cumulative water balance for the north half of the field for the spring 2001
potato crop.

Similar to the moisture content predictions, the predicted nitrate-nitrogen


concentrations compared relatively well to the measured values. Figures 3-6 through 3-9


show that DSSAT generally predicted the temporal and spatial changes in nitrate


concentration within at least one standard deviation of the measured results. Also, the


model responded appropriately to fertilizer applications and changes in moisture content


for the entire soil profile, which is more apparent in the top 15 cm. The large changes









were more evident in the top 15 cm because this zone in the soil profile was where the

nitrogen fertilizer was applied and displayed the largest variations in moisture content.

For example, the nitrate-nitrogen concentration prediction for the top 15 cm increased to

2,500 mg/L on March 8, 2001, which was caused by the 112 kg/ha of nitrogen fertilizer

applied on March 5, 2001. On January 29, 2001, the nitrate-nitrogen concentration

increased to 1,037 mg/L due to nine consecutive days with no water applied.

Even though the model did predict most of the nitrate concentrations within on

standard deviation, there were noticeable under predictions for the nitrate-nitrogen

concentrations below the top 15 cm. For example, the March 2, 2001 soil samples had

measured nitrate concentrations values of 603, 293, and 131 mg/L for the 15-30, 30-60,

and 60-90 cm sampling depths, respectively. These measured values are significantly

higher than the predicted values of 229 mg/L at 15-30 cm, 163 mg/L at 30-60 cm, and 90

mg/L at 60-90 cm. These results indicate that modeled nitrate may be leaching out of the

soil profile too quickly, which could reduce the amount of applied nitrogen recovered by

the potato crop.

When the corrected simulation was compared to Albert's (2002) simulation results

with the doubled fertilizer application rates, there were significant differences between

the predicted values. For example, on March 8, 2001 the nitrate-nitrogen concentration

was predicted to be 10,080 mg/L in the top 15 cm, which is approximately four times

greater than the corrected prediction. On January 29, 2001, the nitrate-nitrogen

concentration in the top 15 cm was approximately two and a half times greater than the

corrected model prediction of 2,500 mg/L. Similar trends are observed through the








60



duration of the computer simulation. Albert's (2002) results were usually two to four


times larger than the corrected simulation predictions.


1/1/2001 1/21/2001 2/10/2001 32/2001 322/2001 4/11/2001 5/12001 521/2001






30
0 a
2000 4
40
S150050

z 1000-

5000


1/1/2001 1/21/2001 2/10/2001 322001 3/22/2001 4/11/2001 5/1/2001 5/21/2001
Time




Figure 3-6. Spring 2001 potato crop nitrate-nitrogen concentration results for the north
half of the field at 0-15 cm. Error bars for the measured values represent one
standard deviation about the measured mean.


1/1/2001 1/21/2001 2/10/2001 312/2001 3M22/2001 4/11/2001 5/12001 5/21f2001
1400 0
o '" I' l' ll II, llllllllllllllll l llll ll ,llll
1200 10

S1000 20
E E
800 30
40
600
50





1/1/2001 1/21/2001 2/10/2001 3)2/2001 3/22/2001 4/11/2001 5/112001 5/21f2001
Time




Figure 3-7. Spring 2001 potato crop nitrate-nitrogen concentration results for the north
half of the field at 15-30 cm. Error bars for the measured values represent one
standard deviation about the measured mean.



















1/1/2001 1/21/2001 2/10/2001 3/2/2001 3/22/2001 4/11/2001 5/1/2001 5/21/2001


900 0

800
20
01 E
EE


S40
400 /1
5oI 5--------------------------------------------------4o


8 50
6 300
200 60

100
70

1/1/2001 1/21/2001 2/10/2001 3/2/2001 3/22/2001 4/11/2001 5/1/2001 5/21/2001
Time
i ., I I



Figure 3-8. Spring 2001 potato crop nitrate-nitrogen concentration results for the north

half of the field at 30-60 cm. Error bars for the measured values represent one

standard deviation about the measured mean.


1/1/2001 1/21/2001 2/10/2001 3/2/2001 3/22/2001 4/11/2001 5/1/2001 5/21/2001
900 0



700 - -- 10
a 20
600 E

500 30

400 40
0
8 300 50
0
Z 200 T- 60

100


1/1/2001 1/21/2001 2/10/2001 3/2/2001 3/22/2001 4/11/2001 5/1/2001 5/21/2001
Time
[ 1 ) II :=. -1 :



Figure 3-9. Spring 2001 potato crop nitrate-nitrogen concentration results for the north

half of the field at 60-90 cm. Error bars for the measured values represent one

standard deviation about the measured mean.


Noticeable differences were also observed between the predicted crop growth



results for Albert's (2002) simulation and the corrected simulation. In Albert's results,









the model tended to agree very well with the measured biomass values, especially dry

tuber yield. For example, the predicted dry tuber yield was approximately 6,900 kg/ha,

which is relatively close to the measured value of 6,840 kg/ha. Also, the results appeared

to accurately represent the generally trend in leaf and stem growth relatively well, but

were usually greater than the average measured values. The agreement between modeled

and measured values was most likely due to the doubled fertilizer application rates, which

provided more nitrogen for plant uptake during the simulation.

When the corrected model's plant growth predictions were examined, it was

noticed that there were significant inaccuracies in the model simulations. The predictions

compared relatively well to the analysis results from the four biomass sample sets

collected by Albert (2002) for the dry leaf (Figure 3-10), dry stem (Figure 3-11), and dry

tuber (Figure 3-12) weights. The first indication that DSSAT was inaccurate was when

the final dry tuber yield predictions were compared to the actual measured yield. The

measured dry tuber yield was determined to be 6,840 kg/ha while the predicted yield was

3,735 kg/ha. The 45% underprediction in dry tuber yield was substantial and the cause

for the underprediction was not initially apparent.

According to Albert's (2002) analysis results, the model predictions were accurate

until final harvest. However, after evaluating the biomass collection method used by

Albert (2002), it was determined that the technique used to collect the biomass samples

was biased. The samples were taken on a per plant basis and the mass per area was then

determined from the planting density. Early in the season the method would be

somewhat correct, but it is virtually impossible to distinguish between individual plants

once the vegetation is well developed later in the growing season. Thus, the biomass











analysis results for the four sets of biomass samples contained a large degree of


inaccuracy and the weight per plant was probably underpredicted, which was why the


early model predictions were similar to the early measured values. However, it still was


not clear why the model under predicted the final tuber yield. The genetic coefficients


used for the Red LaSoda potato crop were reasonable and the moisture content


predictions indicated that there was an ample amount of water available to the plant.


After examining the nitrogen balance (Figure 3-13), it was clear that the model notably


under predicted the amount of nitrogen that was taken up by the plants because the nitrate


was leaching out of the root zone too quickly.





900

800

700

600

500 -





2o
300



100U


02/1501 02A1 03A1A1 0FON1 03/1501 0=AD1 U3R2901 04501 04/12A01 0419/01 04'26AD1 05QU01 0M/1001 05/17/01
Date
-Predcted IVaued


Figure 3-10. DSSAT dry leaf weight predictions for the spring 2001 potato crop on the
north half of the field. Error bars represent one standard deviation about the
measured mean.

















































02/15/01 02/22/01 03/01/01 03/08/01 03/15/01 03/22/01 03/29/01 04/05/01 04/12/01 04/19/01 04/26/01 05/03/01 05/10/01 05/17/01
Date

-- Predicted Measured




Figure 3-11. DSSAT dry stem weight predictions for the spring 2001 potato crop on the

north half of the field. Error bars represent one standard deviation about the

measured mean.


8000


7000


6000


5000


4000


3000


2000


1000


0
02/15/01 02/22/01 03/01/01 03/08/01 03/15/01 03/22/01 03/29/01 04/05/01 04/12/01 04/19/01 04/26/01 05/03/01 05/10/01 05/17/01
Date

Predicted Measured




Figure 3-12. DSSAT dry tuber weight predictions for the spring 2001 potato crop on the

north half of the field. Error bars represent one standard deviation about the

measured mean.


350



300



250



S200



E 150



100



50













450
400
350
300
250 /
S200
150
100



1/1/01 1/15/01 1/29/01 2/12/01 2/26/01 3/12/01 3/26/01 4/9/01 4/23/01 5/7/01 5/21/01
Date





Figure 3-13. Cumulative nitrogen balance for the spring 2001 potato crop on the north
half of the field. Error bars represent one standard deviation about the mean.

DSSAT predicted that only 58.4 kg/ha of the total nitrogen applied was utilized by


the plant, which was 43.3 kg/ha below what was measured. This value is also


significantly lower than that predicted in Albert's simulation. Since Albert doubled the


fertilizer application, the plants took up more nitrogen over the computer simulation. The


total nitrogen taken up was predicted to be approximately 101 kg/ha, which is much


larger than the corrected model prediction. This also shows that Albert's dry tuber yield


prediction was accurate because the increased nitrogen uptake resulted in more plant


growth, and the accuracy of Albert's simulation was purely coincidental.


Several combinations of the crop's genetic coefficients were then used in various


simulations, but none increased plant nitrogen uptake or yield. From these findings and


the observations of low soil nitrate concentrations in the model predictions, it was


determined that the nitrate was leaching out of the soil to quickly because the water


balance was incorrect.









As previously discussed, the soils located at the project site are sandy and tend to

drain relatively quickly. All the samples taken in the field were obtained at times when

the soils had drained to field capacity. So, while the steady-state drained water content

was correct, the volume and rate of water moving through the profile seemed to be

incorrect. This underscores the difficulty in calibrating the hydrology component in the

model. However, the soil parameters were determined from lab experiments and were

reasonable considering the characteristics of the soils located on the project site. After

these findings, it was determined that the DSSAT hydrology component and plant growth

component needed to be modified in order to account for the bed slope and canopy

effects on infiltration; the fertilizer placement effects; and the bed width and depth to

hard pan effects on root depth, root density, and nitrogen uptake.














CHAPTER 4
DSSAT MODIFICATIONS

After the initial DSSAT simulations for the spring 2001 potato crop, it was clear

that DSSAT required modifications in order to properly simulated the potato crop system.

The model underpredicted crop yield and overestimated the nitrate leaching. A possible

source of the modeling error is that DSSAT assumes that water and nitrogen are

uniformly distributed in each soil layer and that the field surface is flat. In actuality, the

potato plants are planted in beds (Figure 4-1) that are maintained throughout the growing

season. The beds, along with a underlying plow pan, reduced the volume of soil

available to plant roots for water and nitrate-nitrogen uptake by approximately half

(Figure 4-1).















Figure 4-1. Illustrations of the potato plant beds (01/28/2003) and root distribution
(04/12/2003).

To investigate these issues and provide motivation and justification to modify

DSSAT, the HYDRUS2D/MESHGEN vadose zone model was implemented. HYDRUS

is a product of the International Ground Water Modeling Center and was developed at the









U.S. Salinity Laboratory Riverside, California. HYDRUS was selected due to its ability

to accurately predict two-dimensional soil-water and solute transport. The primary

purpose of using HYDRUS was to give a general idea of how the nitrate-nitrogen was

being transported through the soil. For examples of the HYDRUS input files, refer to

Appendix D.

HYDRUS Model Description

HYDRUS is a Microsoft Windows based modeling environment used for the

analysis of water and solute flow in a variable saturated porous media. HYDRUS

includes the SWMS_2D two-dimensional finite element model for simulating water and

solute transport and the MESHGEN-2D mesh generator to create unstructured finite

element grids. The model has a graphical user interface that is used for creating input

files, structured mesh generation, and a graphical presentation of the results.

The input files required by HYDRUS vary depending on the simulation options

selected by the user. The model has the ability to predict solute and water transport for

both rectangular and irregularly shape boundaries. The model can simulate a maximum

of six solutes during a simulation, whether they are independent of one another or if they

are part of a chain species. Solute boundary conditions that are specified by the user

include Dirichlet (boundary concentration), Cauchy (prescribed flux concentration),

Neumann, and volatile types (e.g. volatilization of ammonia). Water transport boundary

conditions are comprised of three system independent and three system dependent types.

The three system independent boundary conditions include Dirichlet (specified pressure),

Neumann (specified flux), and specified gradient types (free/deep drainage). The system

dependent boundary conditions consist of an atmospheric type, seepage face type, and tile

drain type. Each water transport boundary condition can be used in combination with









any other water transport boundary condition, but two different boundary conditions

types cannot be applied to the same boundary segment. The same is true for the solute

transport boundary conditions. Also, the variable flux (Neumann type) and atmospheric

boundary conditions are assigned one value per time step and are not allowed to vary

spatially.

Governing Flow Equation

The model considers two-dimensional isothermal Darcian flow of water in variably

saturated rigid porous medium and assumes the air phase flow is negligible. The

governing flow equation for these conditions is given by a modified Richard's equation

(Eq. 4-1).


cO c K KA h+ KA S (4-1)
at ax, i ax 1Z

where Ois the volumetric water content [L3L-3], h is the pressure head [L], S is a sink

term [T-1], x, (i = 1, 2) are the spatial coordinates [L], t is time [T], Kj are components of

the dimensionless anisotropy tensor KA, and K is the following unsaturated hydraulic

conductivity function [L T1]:

K(h, x, z)= K, (x, z)K, (h, x, z) (4-2)

where Kr is the relative hydraulic conductivity and Ks is the saturated hydraulic

conductivity (L T1). The anisotropy tensor is used to account for anisotropic conditions.

The matrix becomes an identity matrix for an isotropic medium. If (4-1) is applied to

planar flow in a vertical cross-section, xl = x is the horizontal coordinate and x2 = z is the

vertical coordinate (positive upward).









Root Water Uptake

The volume of water that is removed per unit time from a unit volume of soil is

accounted for using the sink term (S) in (4-1). The root water uptake routines in

HYDRUS are relatively simplified compared to the methods used by DSSAT. Unlike

DSSAT, HYDRUS requires that the user specify the root distribution and it is considered

to be static throughout the simulation. There are two main root water uptake functions

used in HYDRUS that includes the Feddes and van Genuchten models. The root water

uptake function used in the potato crop simulations was the Feddes model. The Feddes

model is given by the following equation.

S(h) = a(h)S, (4-3)

where a(h) is a dimensionless water stress response function and Sp is the potential water

uptake rate [T-1]. The van Genuchten equation is similar to the Feddes equation, except

the water stress function was expanded to account for osmotic stress.

The potential root water uptake for a non-uniform root distribution of an arbitrary

shape is defined as

S, = b(x, z)LT, (4-4)

where Lt [L] is the width of the soil surface associated with plant transpiration, Tp [L T-1]

is the potential plant transpiration specified by the user, and b(x,z) is the normalized

water uptake distribution [L-2]. The actual root water uptake is then determined by

substituting (4-4) into (4-3):


S(h)= a(h)LT


(4-5)









The Unsaturated Soil Hydraulic Properties

Unsaturated soil hydraulic properties, 0(h) and K(h), are generally highly nonlinear

functions of the soil-water matric potential, which is dependent on soil texture (e.g. clay,

sand, silt). HYDRUS utilizes three different analytical models to describe the hydraulic

properties of soils. The models contained in HYDRUS include the Brooks and Corey

(1964), the van Genuchten (1980), and Vogel and Cislervoa (1998) models. The soil-

moisture characteristics curve for the soils located at the project site were fitted to the

Brooks and Corey (1964) soil-water retention and hydraulic conductivity functions,

which are given by


S, = Iohh h < a (4-6)
1 h>-

K = KS2/n+1+2 (4-7)

respectively, where Se is the effective water content defined as follows

-Or
Se = (4-8)
6 -Or

where Or and 0, are the residual and saturated moisture contents, respectively; Ks is the

saturated hydraulic conductivity, h is the matric potential [L], a is the inverse of the air-

entry pressure, n is the pore-connectivity index, an Iis the pore-connectively parameter

(assumed to be 2.0). HYDRUS considers a, 1, and n to be empirical coefficients that

affect the shape of the hydraulic functions.

To account for the spatial variability of the unsaturated soil hydraulic properties in

the flow domain, HYDRUS uses a scaling procedure that simplifies the description of the

variability. It is assumed that the hydraulic variability in a specified domain can be









approximated using linear scaling transformations (refer to Simunek et. al, 1999 pp. 18-

19) that relate the individual soil hydraulic characteristics to reference characteristics.

There are three independent scaling factors that are used by HYDRUS, which define a

linear model of the actual spatial variability in the soil hydraulic properties.

Governing Transport Equation

The HYDRUS model assumes solutes can exist as liquid, solid, and gaseous phases

and that the decay and production processes can differ in each phase. For example, the

liquid and solid phases can be described as nonlinear nonequilibrium equations, while the

interactions between the liquid and gaseous phases can be assumed to be linear and

instantaneous. The solutes are transported by advection and dispersion in the liquid

phase and by diffusion in the gas phase. The partial differential equations governing two-

dimensional nonequilibrium solute transport involved in a sequential first-order decay

chain during transient water flow in variably saturated rigid porous medium are given by

00C O, 8 aps aR g, 8 ci a g qc, _
a+ + a OD +- aD g Sc,,
at at at x j 9 a I x ax, (4-9)

(- (i + i ^ (,s, + i,,)psi (p +pU gi i, + + +7 P + 7,,a



aOCk aPSk avgk a aCk +a gaC' k aqk
+ + ayODdk + vD k
9 at9t at x, 9x O x "a 9x a x,

(w,k + i, k ) (,k + )pSk -s(pg,k + g,k)g igk + w,k1 Ck- (4-10)
+ ,k-Skl + g,k-lagkl + Yw,kO + Yg,kP+ g,ka -Sc,k kE(2,ns)

where c, s, and g are solute concentrations in the liquid [M L-3], solid [M M-1], and

gaseous [M L-3] phases, respectively; q, is the i-th component of the volumetric flux

density [L T1-]; /w, /s, and Ug are first-order rate constants for solutes in the liquid, solid,








and gas phases [T-1], respectively, /u/, /l/, and /pg first-order rate constants for solutes in

the liquid, solid and gas phases [T-1], respectively, for a chain species, yw, y), and Yg are

zero-order rate constants for the liquid [M L-3 T-1], solid [T-1], and gas [M L-3 T-1],

respectively; p is the soil bulk density [M L-3], av is the air content [L3 L-3], S is the sink

term in the water flow equation (4-1), c, is the concentration of the sink term [M L-3], D,"

is the dispersion coefficient tensor [L2 T-1] for the liquid phase, and D,f is the diffusion

coefficient tensor [L2 T-1] for the gas phase. The subscripts w, s, and g correspond to the

liquid, solid, and gas phases, respectively; the subscript k represents the kth chain

number, and n, is the number of solutes in the chain reaction. The nine zero-order and

first-order rate constants in (4-9) and (4-10) can be used to represent a variety of

reactions or transformations that include biodegradation, volatilization, and precipitation.

HYDRUS assumes equilibrium interactions between the solution and gas phases of

the solute in the soil system. In the graphical user interface, the user can specify

nonequilibrium or equilibrium conditions between the solution and solid phases of the

solute in the soil system. A generalized nonlinear equation (4-11) is used to describe the

adsorption isotherm relating the solid and solution phases of the solute in the soil system.

kk k ~(1,nk
k 1+7k k(ln)
S+7kCk a2 (4-11)
sk k, k k k ck kP ksk k k rk kkCk n(Ck ) k
I + 1+kck k 8k k k k 27 k C 2qk
^f ~(l+^ ) 8t 1+ r 8k2 dt 0(l+^)2 +t (l+r/cf)2 8t

where ks,k [L3 M-1], 8k [-], and /k [L3 M-1] are empirical coefficients. Equation (4-11) can

be used to represent Langmuir (/lk=), Freudlich (qk=0), and linear (Ak=l and rk=0)

adsorption isotherms. Solute transport without adsorption is represented by ks,k=0. The

empirical coefficients are assumed to be independent of solute concentration, but are









allowed to change as a function of temperature if the user selects the option. The

concentrations of the solution and gas phases are related by the linear equation

gk = kg,kCk (4-12)

where kg,k is an empirical constant [-] that is to (KHR,T1)-'. KH is Henry's Law constant

[M T2 M-1 L-2], R, is the universal gas constant [M L2 T-2 K-1 M'1], and TA is the absolute

temperature [K].

HYDRUS Results and DSSAT Modifications

HYDRUS Results

The HYDRUS model was used to simulate nitrate transport for both flat and

bedded soil surfaces in order to investigate the influences of model geometry and

fertilizer placement on water and nitrate-nitrogen transport. The first simulation was

based on the DSSAT geometry, which assumes that the field is flat and that the nitrogen

fertilizer is evenly distributed across the entire field. The fertilizer was applied uniformly

over the entire soil surface. The second run simulated the two-dimensional bedded

surface to demonstrate the effects of the bed shape and fertilizer placement on water and

nitrate-nitrogen transport. In the second simulation, the fertilizer application was

introduced in the soil profile using two circular 1 cm diameter variable boundaries with

specified fluxes to simulate the field practice of banding the nitrogen fertilizer in the

beds. Both simulations received identical fertilizer application amounts. To illustrate the

differences between the flat and bedded soil surfaces, the nitrate transport of the January

10, 2002 fertilizer application (refer to Table 2-6) on the north half of the field was

analyzed. The rainfall and irrigation applied during the HYDRUS simulation was

identical to that used in the DSSAT simulations. The transport of the January 10, 2002









fertilizer application was analyzed because there were significant amounts of rainfall

received by the crop over this period. Over the duration of the simulation, there were

three consecutive rainfall events of 1.1, 0.8, and 4.9 cm that occurred from January 12,

2002 through January 14, 2002, respectively, which contributed to the relatively rapid

nitrate-nitrogen leaching. Note that HYDRUS does not determine runoff and any water

that does not infiltrate is immediately removed from the soil surface.

The boundary conditions used for the upper and lower boundaries of the soil profile

were atmospheric and free drainage, respectively. It is required in HYDRUS that the user

specifies the potential evaporation and potential transpiration in the input file for

atmospheric boundary conditions. Thus, the potential evaporation and potential

transpiration that was calculated by DSSAT was used in the HYDRUS simulation.

Plant roots were distributed evenly in the soil profile to a maximum depth of 30 cm

in the HYDRUS simulations in order to account for plant root uptake effects on nitrate-

nitrogen concentration and moisture content. The default parameters contained in

HYDRUS for potatoes were used to estimate the root water uptake, however the wilting

point was reduced from -15, 000 to -6,000 cm due to instabilities in the model at low

moisture contents.

Flow was assumed to be symmetrical from row to row, so no flux boundary

conditions were used in the center of each furrow. Soil parameters for porosity, wilting

point, bulk density, hydraulic conductivity are the same as those used in DSSAT. Figure

4-2 through Figure 4-4 are the soil-moisture characteristic curves (SMCC) for the soils at

the project site.








76




10000





1000





100 ,





















Brooks and Corey equation.


6000
2000






1000
0 12 017 022 027 032 037




















Moisture Content




Figure 4-3. SMCC of the soil metric potential versus moisture content forcing the top 45 cm
of the soil profile using the Brooks and Corey equation. Note the points















represent measured values.01











6000



5000



4000



3000



2000



1000



0 ---,---I n
0 005 0 1 0 15 02 025 03 035 04
Moisture Content



Figure 4-4. SMCC of the soil matric potential versus moisture content for the bottom 45
cm of the soil profile using the Brooks and Corey equation. Note the points
represent measured values.

Nitrogen transport and degradation parameters were based on the values used by

Albert (2002). The fertilizer was applied to the field as ammonium-nitrate with equal

portions of each nitrogen species. The degradation of the compound from ammonium to

nitrate was calculated for the entire nitrification chain (refer to Chapter 1) using first-

order kinetics. The sorption of ammonium to the soil colloids was modeled as a

Langmuir Isotherm. Both sets of parameters for sorption and degradation were based on

default values for sandy soil contained in an example problem in the HYDRUS program.

Both sets of results for the flat (Figure 4-5) and bedded (Figure 4-6) indicate that

nitrate is transported rapidly out of the soil profile regardless of the upper boundary

condition. Figure 4-7 shows that the flat row simulation begins to leach nitrate out of the









bottom of the profile sooner than the bedded row, but both cases leach nitrate at the same

rapid rate on day 5 (01/14/02) when 4.9 cm of rainfall occurred. Figures 4-5 and 4-6

show that until day four, most of the nitrate-nitrogen remained in the top 30 cm of the soil

profile, which encompasses the root zone. On day 5 of the simulation, 4.9 cm of rainfall

infiltrated into the soil profile, which caused the nitrate-nitrogen to move into the bottom

30 cm of the soil profile and out of the root zone for both simulations. It should also be

noted, however that HYDRUS does not account for canopy effects, which likely reduce

infiltration rates for the potato crop system.

In the flat row simulation, the nitrate-nitrogen transport is virtually one-

dimensional, while the bedded simulation displays two-dimensional transport of the

nitrate-nitrogen in the soil profile due to the limited lateral dispersion in the soil profile.

The bedded simulation results show that there are significant increases in the nitrate

concentrations in the bed when the fertilizer is band applied. The maximum nitrate-

nitrogen concentrations for the bedded surface were generally two to three times greater

than those for the flat surface. Also, the nitrate-nitrogen was concentrated in the bed,

particularly the root zone, which provides more nitrogen was available for plant uptake.

Thus, the results of the HYDRUS simulations indicate that although nitrate moves at the

same rate through the flat and bedded simulations (especially when canopy effects are

neglected) the nitrogen remains concentrated in the root zone in the bedded simulations,

which is very important for accurately simulating plant growth. This illustrates the

importance of incorporating the actual bed geometry in the DSSAT model.
























0E3 1E3 2E3 3E3 4E3 5E3 6E3 0E3 500 1000 1500 2000 2500 3000
1 1 1 1 1 1 1 1 1 1 1 1 1 1


0 500 100 150 200 250 40 60 80 100 120 140 160 180
i I I I I MM MM I I I I I I


10 20 30 40 50 60 70 80


(e)
Figure 4-5. Flat upper boundary nitrate concentration spectral map for the top 90 cm on
the north half of the field for 01/10/02 through 01/14/02 (a-e). Spectral scale
units are in mg/L.


I I MO im I MEi Ei

























OE3 2E3 4E3 6E3 8E3 10E3 12E3 14E3 16E3 18E3 20E3 0E3
I I I I I I I I I I I I


) 50 100 150 200 250 300 350 400 450
I iI I I I I


3 50 100 150 200 250
I M M I I I


0 10 20 30 40 50 60 70


(e)
Figure 4-6. Irregularly shaped upper boundary nitrate concentration spectral map for the
top 90 cm on the north half of the field for 01/10/02 through 01/14/02 (a-e).
Spectral scale units are in mg/L.


i 'w ~ mml .


i I I M A I =0 i


1E3 2E3 3E3 4E3 5E3 6E3
I i I I I I















25

120

15







1/9/2002 1/1/22 1/102200 2 1311/200 2 1/124/22 2 1/135/22 2 1/1 4/22 2 1/1 5/22 2 112 2 /17/2002 1/18/2002
Date



Figure 4-7. Cumulative nitrate-nitrogen leached out of the top 90-cm from the January
10, 2002 fertilizer application.

These results, along with the field observations, show that to improve its predictive

ability, the DSSAT model should be modified to reduce the amount of soil volume

accessible by the plant roots, concentrate the applied fertilizer into the beds, and reduce

the amount of infiltration due to canopy effects. The next step was to review the DSSAT

source code and make the proper modifications within the code to account for these

conditions.

DSSAT Modifications

Before any modifications were made to the model, one of the DSSAT model

developers, James W. Jones, was consulted in order to determine the necessary changes

in the DSSAT source code. As previously stated, the goal was to reduce the soil volume

accessible to the plant roots and concentrate the fertilizer applications in the beds.

Following Dr. Jones's suggestions, it was decided that the best approach for modifying

DSSAT was to leave the water balance unchanged, while making all the needed changes









in the crop growth module (GROSUB). Since the water balance was the same, it was

necessary to change the row width used in the DSSAT input file to the bed width, which

reduced the amount of soil volume available to plants by 50%. In order to account for the

fertilizer applications being concentrated in the beds, the fertilizers application rates in

the input file were doubled to concentrate the fertilizer applications in the bed rather than

distribute the application across the entire field. The source code was then modified, with

the aid of Cheryl Porter and Dr. James Jones of the Agricultural and Biological

Engineering Department at the University of Florida, in order to maintain the same light

interception by the potato plants in spite of using bed width rather than row width as the

basis of the simulation.

In the GROSUB module, the potato plants are grown as individual plants and the

variable PLTPOP is the number of plants per square meter at emergence. The daily

growth is calculated by dividing the overall growth per square meter by the plant

population. The leaf area index (LAI) is calculated by multiplying the leaf area per plant

(PLA) by PLTPOP. Plant biomass per meter square ground area is determined by

multiplying the biomass per plant by PLTPOP to get plant mass per ground area.

In order to account for the plants being grown on a bed area basis rather than on a

row basis (Figure 4-8), the PLTPOP must be entered as plants per bed area rather than

plants per row area in the input file. This allows the soil computations to remain the

same. Since the model simulates plant growth on a row area basis, the actual LAI must

then be calculated by multiplying the LAI computed on a bed basis by BWRATIO (bed

width/row width). The variable BWRATIO is not included in the input file so it is

declared locally in the GROSUB module.









Light Interception Light Interception Domain
Sand Root Domain I ______I_11




Root Domain










(a) (b)
Figure 4-8. A comparison of the light interception and root domain for flat (a) and
bedded (b) rows.

The daily growth (PCARB, grams per plant per day) accounts for the plant growth

on a row area basis. Since the LAI has already been modified to account for the entire

row area, the daily growth is then computed on a row area basis. The daily growth must

then be calculated on a bed area basis by dividing PCARB by BWRATIO. The resulting

biomass output file is then on a bed area basis and must be multiplied by BWRATIO in

order to convert them to a row area basis. The LAI in the output file is on a row area

basis and does not need to be adjusted. To review the actual changes in the source code

refer to Appendix E.

The dense plant canopy (Figure 4-9) and steep bed slope have a major influence on

the amount of effective rainfall infiltrating into the plant bed. However, the SCS curve

number method used in the DSSAT model does not adequately predict the reduction in

infiltration caused by the bed slope and potato plant canopy. As a result, the infiltration

that occurs over the growing season usually results in the model leaching the nitrogen

fertilizer out of the soil profile too quickly with significant under predictions in dry tuber









yield (Chapter 3). In an attempt to account for the bed and canopy effects on infiltration,

a modified SCS curve number curve number was introduced. Determination of the

modified CN was primarily comprised of increasing the CN until the nitrate-nitrogen

concentration and moisture content results, shown in the following chapter, agreed

relatively well with the measured values. The modified CN is necessary to decrease the

infiltration in the bed, which should increase the nitrogen available to the potato plants

and significantly increase plant growth. Note that a more physically-based method

should be developed for future research for potato crops grown on sandy soils, which can

accurately predict the spatial and temporal variability in the effective rainfall and the

localized runoff caused by the developing plant canopy and bed slope.


Figure 4-9. Potato plant canopy illustration.














CHAPTER 5
MODIFIED DSSAT RESULTS AND DISCUSSION

After all the appropriate modifications were made in the DSSAT source code and

in the input files, the model was then calibrated using both the spring 2001 and 2002

potato crop data. The calibration methods for the modified model were the similar to

those discussed in Chapter 3. The genetic coefficients for crop growth used by the model

were the same as those used by Albert (2002). Soil parameters including porosity,

drained upper limit, wilting point, drainage coefficient (SWCON), and porosity were also

identical to those used by Albert, except the CN was increased from 75 to 95 in order to

account for plant canopy and bed slope effects on infiltration. Note that the irrigation and

rainfall were not modified for the bed simulation because the water was applied

uniformly over the soil surface. As previously stated, the spring 2001 potato crop

received similar management practices on the north and south halves of the pivot, so only

the north half results will be shown in this section. Since the spring 2002 potato crop had

more pronounced differences between management practices on the north and halves,

simulation results for both the north and south halves of the field are included in this

section. Refer to Appendix F for the modified DSSAT input files.

Soil-Water Transport Results

2001 Potato Crop

Figures 5-1 through 5-4 illustrate the insensitivity of the soil moisture prediction

from the DSSAT model to changes in the volume of infiltrating water. Even with the

increased CN, the model still tended to agree quite well with the measured values and







86


displayed the same general temporal and spatial changes in the moisture contents as the

previous simulation results shown for the 2001 crop discussed in Chapter 3. However,

the peaks in the moisture contents were usually 1-3% lower using the modified model

relative to the previous simulation, because of the decreased infiltration volume due to

the increased CN.

Even though the increased CN had a small effect on the predicted moisture content

results, there were noticeable differences between the original DSSAT model and the

modified model for the cumulative water balance (Figure 5-5). Unlike the previous

simulations (Figure 3-5), localized runoff (to the furrows) occurred because of the

increased CN. Thus, the cumulative infiltration in the beds was reduced by 4.88 cm and

the drainage decreased from 21.8 to 17.6 cm due to the runoff





1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
025 10
II || ,I ,i|1 l" | I l i II' iiii i lililili l ii ii iiiii l 10

0 20
IE 20
E 015
30


460
010 40


60

000 0 70
1/1/01 1/21/01 2/10/01 3/2/01 3/22/01 4/11/01 5/1/01 5/21/01
Time



Figure 5-1. Comparisons between the predicted and measured moisture contents at 0-15
cm for the north half of the field 2001 potato crop. Error bars represent one
standard deviation about the average measured value.