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1 INORGANIC NITROGEN LEACHING AN D AGRONOMIC RESPONSE OF ST AUGUSTINEGRASS TO NITROGEN FERT ILIZATION STRATEGIES UNDER RESIDENTIAL LAWN CONDITIONS By NEIL GRAHAM MILLER YOUNG A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009
2 2009 Neil Graham Miller Young
3 To mum and dad who gave the encouragement and support to go back to school
4 ACKNOWLEDGMENTS Sincere thanks are accredited to Dr. John Cisa r for providing the opportunity to study and work in a discipline I love, for always m aking time to discuss technical and scientific matters, and for making research entertaini ng. Gratitude must be expresse d to Dr. Snyder for agreeing to chair my committee despite having retired, alth ough fortunately, Dr. Snyders definition of retirement differs from most. Unlike any one I know, Dr. Snyder. has an uncanny ability to furnish knowledge without trying and on every singl e occasion I had the pleas ure of talking with him I learned something new about soil fertility and field research. I th ank Drs. Sartain and Erickson who patiently served on my committee and provided great scientif ic incite into my research. The support and advice from Ms. Karen Williams was extremely valuable. The huge contributions and help from Ms. Eva King with tissue preparation and di gestion were greatly appreciated. Thanks are given to Mr. Bill Latham for providing analytical training and always being available when problems arose with my wa ter analysis. Great than ks are given to Dr. Wright for providing the full use of his laborator y. The humor, support, an d analytical prowess of Dr. Luo made tissue nitrogen determinations an absolute joy. I credit my parents Dr. Graham and Anne Young whose encouragement and support ma de this experience possible. I express my undying gratitude to my girlfriend Rachel who provided endless amounts of help with all facets of my research, who was extrem ely understanding about the lack of time I could devote to her, and for listening to my boring conversions about soils and plants. The support, opportunities, and professional development advice that Dr. Kath ie Kalmowitz has provided through my graduate schooling has been thoroughly appreciated. Finally, the author would like to thank the Florida Department of Environmental Protection for providing the funding for this experiment and for their continued support of environmentally based so il and water research that greatly benefits the State of Florida.
5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ............................................................................................................... 4LIST OF TABLES ...........................................................................................................................7LIST OF FIGURES .........................................................................................................................9ABSTRACT ...................................................................................................................... .............10 CHAP TER 1 INTRODUCTION .................................................................................................................. 12St. Augustinegrass Land use influenced Demographics ......................................................... 12Anthropogenic and Ecological Implications from Lawn Fertilization ................................... 12Fertilizer Ordinance and Labeling Restrictions ......................................................................132 THE INFLUENCE OF VARIOUS NI TROGEN STRAT EGIES ON ST. AUGUSTINEGRASS QUALITY, DENSITY, YIELD, AND NITROGEN UPTAKE. .......16Introduction .................................................................................................................. ...........16Nitrogen (N) Source Categorization and Benefits .................................................................. 16Biosolid N Management under Turfgrass Conditions ..................................................... 17Controlled-Release Liquid N Sources in Turfgrass .........................................................18Polymer-Coated Urea Ferti lization in Turfgrass .............................................................19Research Objectives ........................................................................................................... .....19Materials and Methods ...........................................................................................................20Visual Assessments ......................................................................................................... 22St. Augustinegrass Tissue Ha rvest and Analysis ............................................................ 22Statistical Design and Analysis .............................................................................................. 23Results and Discussion ........................................................................................................ ...23Comparisons of N Sources Base d on N-Release Categorization .................................... 23Comparisons of N Sources Applied at 49 kg ha-1 at 60-d Intervals ................................ 26Comparisons of N Sources Applied at 98 kg ha-1 at 120-d Intervals ............................. 29Comparisons within N Sources Applied at 147 kg ha-1 at 180-d Intervals ..................... 32The Relationship between Controlled -Release Nitrogen Rate and St. Augustinegrass Yield ...................................................................................................35Conclusions .............................................................................................................................363 INORGANIC NITROGEN LEACHING FR OM ST AUGUS TINEGRASS IN RESPONSE TO NITROGEN FERTILIZATION STRATEGIES UNDER RESIDENTIAL LAWN CONDITIONS ................................................................................47Introduction .................................................................................................................. ...........47Research Objectives ........................................................................................................... .....49
6 Materials and Methods ...........................................................................................................50Construction Specifications of the Field-Based N Leaching Facility ............................. 51Percolate Sampling and Fi eld Quality Assurance ........................................................... 52Percolate Water Sample Analysis and Laboratory Quality Assurance ...........................53Results and Discussion ........................................................................................................ ...54Flow-Weighted NOx-N Concentrations Influenced by N Source and Hydrology .......... 54Nitrogen Leaching Influenced by N Source ....................................................................60Relative Recovery of Inorganic Ni trogen in Percolate and Clipping .............................. 61Potential Nitrogen Losses other th an Leaching or Plant Uptake ..................................... 62Conclusion .................................................................................................................... ..........66APPENDIX A CLIMATOL OGY DAT A ....................................................................................................... 84B PERCOLATE VOLUMES ...................................................................................................855LIST OF REFERENCES .............................................................................................................866BIOGRAPHICAL SKETCH .......................................................................................................966
7 LIST OF TABLES Table page 2-1 Effect of fertilizer treat m ents on selected soil characteristics averaged over the 24mo study period. ...............................................................................................................382-2 Nitrogen (N) source descripti on and application information. ......................................... 392-3 The influence of N source, application ra te, and frequency on average visual quality over 60-d cycles across 2007 and 2008. ............................................................................ 402-4 The influence of N source, applicatio n rate, and frequency on visual density evaluated ~ every 3-mo across 2007 and 2008. ................................................................. 412-5 The influence of N source, application rate, and frequency on dry weight yield over each 60-d cycle across 2007 and 2008. ..............................................................................422-6 The influence of N source, application rate, and frequency on nitrogen uptake over each 60-d cycle across 2007 and 2008. ..............................................................................433-1 The influence of N source applied at 49 kg N ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 60-d cycle across 2007 and 2008. ........................... 683-2 The influence of N source applied at 98 kg N ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 120-d cycle across 2007 and 2008. ......................... 693-3 The influence of N source applied at 147 kg ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 180-d cycle across 2007 and 2008. ......................... 693-4 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 June 30, 2007). .............................................................. 733-5 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 2 (July 1 August 31, 2007). ............................................................... 743-6 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 3 (September 1 November 7, 2007). ................................................ 743-7 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 5 (January 6 March 7, 2008). ........................................................... 753-8 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 6 (March 8 May 9, 2008). ................................................................ 753-9 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 7 (May 9 July 7, 2008). .................................................................... 76
8 3-10 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 8 (July 8 September 6, 2008). .......................................................... 763-11 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 9 (September 6 November 13, 2008). .............................................. 773-12 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 10 (November 14 January 13, 2008). ............................................... 773-13 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 11 (January 14 March 12, 2008). .....................................................783-14 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 12 (March 13 May 15, 2008). .......................................................... 783-15 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 August 31, 2007). .......................................................... 793-16 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 3 (January 6 March 7, 2008). ........................................................... 803-17 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 4 (May 16 September 6, 2008). ........................................................ 803-18 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 5 (September 7 January 13, 2008). ................................................... 813-19 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 6 (January 14 May 15, 2008). .......................................................... 813-20 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 November 7, 2008). ....................................................... 823-21 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 3 (May 10 November 13, 2008). ...................................................... 833-22 Nitrogen budget of inputs vs. N accounted for by N leaching and St. Augustinegrass N uptake for cycle 4 (November 13 May 15, 2008). ...................................................... 83A-1 Climatology data (May-April, 2007 and 2008) for Ft. Lauderdale Research and Education Center (FLREC), FL, with long term norms. ................................................... 84
9 LIST OF FIGURES Figure Page 2-1 The duration of acceptable St. Augustinegrass quality (i.e ratings 6) provided by controlled release nitrogen sources (CRNS) applied at 147 kg N ha-1 prior to the 4mo rainy season fertilization on April 30, 2007.. ..............................................................442-2 The duration of acceptable St. Augustinegrass quality (i.e ratings 6) provided by CRNS applied at 147 kg N ha-1 prior to the 4-mo rainy season fertilization on May 15, 2008..............................................................................................................................452-3 The relationship between CRNS rate (i.e. 49, 98, 147 kg N ha-1) and average St. Augustinegrass yield during the 60-d period following initial fertilization in 2007. ........ 463-1 NOx-N leached in cycle 1 (April 30-A ugust 31, 2007) influenced by N sources applied every 120-d at 98 kg N ha-1 and precipitation duri ng the wet season (WS).. ....... 703-2 NOx-N leached in cycle 4 (May 10-September 6, 2008), influenced by N sources applied every 120-d at 98 kg N ha-1 and precipitation during the WS ...................... 703-3 NOx-N leached during cycles 1-3 (May 10September 6), influenced by N sources applied every 60-d at 49 kg N ha-1 and precipitation during the WS ........................713-4 NOx-N leached in cycle 1 (April 30 Novemb er 7), influenced by N sources applied at 147 kg N ha-1 every 180-d and precipitation during the WS .....................................713-5 NOx-N leached during cycles 3 and 4 (M ay 10, 2008 May 15, 2009), influenced by N sources applied at 147 kg N ha-1 every 180-d and precipitation. ...................................72B-1 Percolate volumes averaged across each treatment collected over the 24-mo study period, indicating generally lower percolate during the dry season.. ........................85
10 Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Master of Science NITROGEN LEACHING AND AGRONOMIC RE SPONSE OF ST AUGUSTINEGRASS TO NITROGEN FERTILIZATION STRATE GIES UNDER RESIDENTIAL LAWN CONDITIONS By Neil Graham Miller Young December 2009 Chair: George Snyder Major: Soil and Water Science In Florida, residential landscape fertilization le gislation limits per-app lication nitrogen (N) rates to 49 kg ha-1, prevent fertilization during the wet s eason, and control soluble-N to reduce NO3-N in ground-water. Insufficient data are availabl e to assess the efficacy of N-rate regulation. The performance of controlled-release N sources (CRNS) and their cap acity to leach N under abundant seasonal precipitation on St. Augustinegrass [ Stenotaphrum secundatum Walt. Kuntze] grown on fine sand (Siliceous, hyperthermic Lythic Psammaquent) is unknown. Higher perapplication rates of CRNS may sustain agronomic responses (i.e. turf quality, density, growth, and N-uptake) during restrictiv e seasons. A 24-mo field study compared these agronomic responses and N leaching from polymer-coated ur ea (PCU), controlled-release liquid (CRL), and biosolid (BSD) applied at 49, 98, and 147 kg N ha-1 on 60, 120, and 180-d re-application intervals, respectively. Equal N combinati ons of PCU and urea, at 49 and 98 kg N ha-1 every 60 and 120 d, respectively provided responses equal to urea, which served as the base for comparison at 49 kg N ha-1 every 60-d. Residual N carryover from preceding cycles was an important agronomic factor for PCU and BSD at 49 kg N ha-1. Of the CRNS, PCU at 98 kg N ha1 provided the best responses. At 147 kg N ha-1 BSD and PCU were capable of sustaining
11 acceptable turf quality throughout restri ctive seasons, with negligible NO3-N leaching. Initially, urea at 49 kg N ha-1 produced maximum leaching losses of 12% of applied N. In subsequent fertilization cycles, N leachi ng was greatly reduced despit e intense hydrological events, indicating N utilization may improve under adeq uate plant available nitrogen (PAN). Reapplication intervals (180-d) in excess of manufac ture recommendations for CRL at 147 kg ha-1 resulted in progressively lower turf density and increased N leaching. Our findings suggest soluble-N rate restrictions prevent excess N le aching. However, rate regulation of certain CRNS prevents judicious N fertilization throughout restri ctive seasons and if St. Augustinegrass density declines during this period due to limited PAN, greater N leaching may result once fertilization resumes.
12 CHAPTER 1 INTRODUCTION St. Augustinegrass Land use influenced Demographics Since 1990, dem ographic data reports the populat ion in Florida has increased by 31.9% to approximately 18.3 million residents (United States Census Bureau, 2008). Anthropogenic intrusion of this magnitude has shown to drastica lly alter the nitrogen (N) cycle and more than double the production rate of reactive nitrogen (Galloway and Cowling 2002; Galloway et al. 2004) with detrimental consequences to ecologica l systems and human health (Wolfe and Patz, 2002). Urban development in the US requires the inclusion of urban and domestic landscapes with St. Augustinegrass sod production increasing dramatically in Fl orida to support urban expansion (Haydu and Cisar, 1990). Recent la nd use trends suggest St. Augustinegrass Stenotaphrum secundatum (Walt.) Kuntze landscapes encompass an estimated at 810,000 ha in Florida (Trenholm and Unruh, 2007). In recent years, improving wate r resources in Florida has become a key concern for regulatory bodies and has lead certain factions to implicate fertilization practices on u rban landscapes as a potential non-point source c ontributor to N species degradation of surface and ground water. Anthropogenic and Ecological Implications from Lawn Fertilization As hum an populations escalate so does the demand for safe drinking water that must not exceed the Maximum Contaminant Level (MCL) of 10 mg L-1 as NO3-N set by Environmental Protection Agency (EPA) for human safety. Petr ovic (1990) reported th at groundwater accounts for 86% of water resources and provides 24% of drinking water for urban areas in the contiguous USA. According to the United States Geological Survey, 1% of public water supplies, 9% of domestic water wells, and 21% of shallow wells in agricultural communities contain nitrate (NO3-N) in excess of the MCL stan dard. Serious human health c oncerns are associated with
13 consumption of excessive NO3-N in drinking water. High level NO3-N ingestion is involved in the aetiology of human cancer (Fra ser et al. 1980), with increased incidences of gastric cancer (Knight et al., 1989; van Leeuwen et al., 1999) and brain tumors (Mueller et al., 2004). More publicized, however, has been th e incidence of methaemoglobin aemia or blue-baby syndrome where infants display symptoms of hypoxia (Mansouri, 1985). Townsend et al. (2003) reported th e eutrophication of coastal and marine ecosystems may be an ecological factor that affect s human health, due to the increa sed occurrence of harmful algae blooms (HAB) in coastal water as a result of an thropogenic nutrient loading. On the West coast of Florida the nearly annual occurrence of HAB, comm only known as Florida Red Tide, is due to the toxic Dinoflagellate Karenia brevis or other closely relate d species, which are linked to marine mortalities and human illness (Van Dolah, et al., 2009). Sources of NO3-N contamination of groundwater are diverse and includ e effluent from septic tanks, animal and human waste, and fert ilization of agricultur al lands (Keeney, 1986). Flipse et al. (1984) proposed NO3-N from applied fertilizer N to urban turfgrass landscapes was a primary source of ground-water contamination wh ere these areas were a major land use. In Florida, fertilizer N leaching to groundwater fr om urban landscapes has been implicated as a potential non-point source contributor to the coastal marine eutrophication and in particular the increasing incidence of Florida Red Tide in Sarasota Bay. Fertilizer Ordinance and Labeling Restrictions Even though no scientific evidence currently links N loading from urban landscapes with nutrient pollution in the Gulf of Mexico, c ities and municipalitie s have responded with heightened regulatory restriction on urban fertilizati on practices in efforts to control red tide outbreaks. These local government ordina nces and resolutions supersede state-wide f ertilizer
14 labeling legislation that was designed to moderate N speci es degradation of surface and ground water resources. The state fertilizer labeling rule restricts per application N-rates to 49 kg N ha-1, of which, the water-soluble N portion should not exceed 34 kg N ha-1 (Department of Agricultural and Consumer services (DACS), No. 4640400, Rule 5E-1.003, 2007 ). St. Johns County introduced the first restric tive fertilization ordi nance on October 24, 2000; when Guana Marsh Basin was identified as a crit ical sink for leached N. The enactment limited the portion of soluble N applied from May 15 to October 15 and constrained annual N applied as fertilizer to 196 kg ha-1 (Ordinance No. 2000-60), although three years later this enactment was largely repealed with less stringent regulation (Ordinance No. 2003-52). Amidst growing concern over the impact of severe red tide outbreaks on Floridas multi-million dollar tourism and fishing industries the previous year, resolution No. 2006-126 was proposed on May 24, 2006 that called for counties and cities in the Southwest Florida Region to uniformly adopt regulatory urban fertilizer ordinances (Council of the City of Sannibel, Agenda item #4[b], 2006). On March 6, 2007, the City of Sanibel enacte d Ordinance No. 07-003 (Council of the City of Sannibel, Water Resources Department) and la ter that year Saraso ta County adopted the Fertilizer and Landscape Management Code (Board of County Commissioners of Sarasota County, Ordinance No. 2007-63). These legislativ e codes prohibit N fertilization during the traditional rainy season in South Florida from June 1 through September 30, restrict annual N applied as fertilizer to 196 kg ha-1, and further limit the per-ap plication soluble N portion of fertilizer to 24.5 kg ha-1. The City of Cape Coral passed si milar fertilizer legislation with Resolution 72-07 on August 29, 2007 (Com missioner Dolores Bertolin, personnel communication), although seasonal restrictions were not impose d. In 2008, Lee and Charlotte Counties followed suit with Ordinance No. 08-08 and 2008-028, respectively. However, only
15 Charlotte County chose to follow state Best Ma nagement Practices (BMP) guidelines (FDEP, 2008) and limit annual N to between 196 and 294 kg N ha-1 for St. Augustinegrass in South Florida. Fertilizer applicati on limits of 49 kg N ha-1 have been imposed unilaterally across all Nsources and may negate the best features of c ontrolled-release nitrogen sources (CRNS) that have been shown to be more effective when applied at infrequent hi gher per-application rates (Skogley and King, 1968; Hummel and Waddington, 1984; Williams et al., 1997) with reduced potential for N leaching (Rieke and Ellis, 1974; Brown et al., 1977; Nelson et al., 1980; Snyder et al. 1981, 1984; Engelsjord and Singh, 1997; Guillard and Kopp, 2004). These enactments may rule out judicious fertilization with higher rates of CRNS and sustain good turf quality and root growth, before, during, and af ter restrictive rainy season periods and limit N leaching,. There is a clear need to evaluate N-loss and agronomic responses of St. Augustinegrass under variable N-source management and application regimes to better understand the efficacy of Nrate regulation. The evaluation of N leaching under CRNS fertilization of St. Augustinegrass may provide valuable information for regulatory b odies to determine if the same stringent rate regulation is applicable to all so urces and to ascertain if higher pre-application rates of these Nsources, prior to restrictive seasons can sust ain turf vigor for ex tended periods without environmental consequences. Urban landscape fertiliz er ordinances as they are currently written may have damaging agronomic and environmental implications. Ultimately, if the goal is to promote urban landscapes that have aesthetic value, while limiting N-pollution, all factors involved with residential lawn fertilizati on and N-deposition must be considered.
16 CHAPTER 2 THE INFLUENCE OF VARIOUS NITROGEN STRAT EGIES ON ST. AUGUSTINEGRASS QUALITY, DENSITY, YIELD, AND NITROGEN UPTAKE. Introduction Urban landscapes have been im plicated as a potential non-point s ource contributor to nitrogen (N) species degradation of surface a nd ground water (Petrovic, 1990; King and Balogh, 2008). Recent land use trends suggest an increasing use of St. Augustinegrass [ Stenotaphrum secundatum (Walt.) Kuntze], in urban landscapes w ith currently an estimated 810,000 ha in Florida (Trenholm and Unruh, 2007). Statewide f ertilizer labeling legislation in conjunction with city and municipality restrict ions have been introduced i n response to m ounting concerns over the impact of urban fertilization practices on Fl oridas water resources. These enactments were introduced prior to determining N leaching charac teristics or agronomic responses of controlledrelease N sources (CRNS) on St. Augustinegrass and may have inadvertently constrained optimal CRNS management strategies (i.e. less frequently applied, higher per-application Nrates) that reduce inputs such as la bor, time, and energy (Trenkel, 1997). There is a clear need to evaluate the agronomic responses of St. A ugustinegrass under varying N sources, application rates, and frequencies to better understa nd the efficacy of N rate regulation. Nitrogen Source Categorization and Benefits Nitrogen-b ased fertilizers for residential lawns ar e broadly categorized ei ther as quick or as controlled release, depending on release duration (Turner and Hummel, 1992), although several sub-classes exist within these delineations (O ertli, 1980). The benefits of controlled-release fertilizers have been well documented, the most notable of which include reduced NO3-N leaching (Rieke and Ellis, 1974; Brown et al ., 1977; Nelson et al., 1980; Snyder et al. 1981, 1984; Petrovic, 1990) and lower water use (Subj arit and Trenholm, 2005). While greater N-
17 uptake efficiency in response to quick-releas e N has been shown in the greenhouse for St. Augustinegrass relative to other warm season grasses (Bowman et al., 2002), little is known about St. Augustinegrass responses under vari ed CRNS management regimes. Numerous CRNS are commercially available for lawn-care use and stringent fertilizer restrictions exemplify the need to evaluate each N source to determin e specific rate and fr equency recommendations. Biosolid N Management under Turfgrass Conditions Milorg anite (BSD), an activated aerobically dige sted biosolid (Chinault and OConnor, 2008), is composed of ~20 % so luble N (Sartain, 1999) and has been evaluated extensively on turfgrass (Turner and Hummel, 1992), although studies pertaining sp ecifically to St. Augustinegrass are limited. Many bio-solid-based fe rtilizers are marketed. Each has its own set of characteristics. Since Milorganite has been used on turfgrass for over 80 years, it often is used as a standard for biosolid fertilizing and ther efore was chosen for this study. Chinault and OConnor (2008) reported the chemical characterist ics of BSD and reported a C/N ratio of 6.0; a ratio that Wolf and Snyder, (2003) maintain should permit relatively rapid microbial decomposition. In contrast, Sartain (1999) repor ted BSD compared less favorably to mixed component organic N-sources fo r St. Augustinegrass qua lity; inferring N-release was too gradual from the unilateral mineralization rate of the or ganic material. Other stud ies noted slow initial responses or lower visual quality compared to soluble N sources (Moberg et al., 1970; Volk and Horn 1975; Carrow, 1997). Several incubation studies have examined N recovery from BSD. Lee and Peacock (2005) found ~60% of applied N was recovered after 70-d, whereas Sartai n et al. (2004) reported only ~40% of applied N was recovered following 180 -d of aggressive ex traction procedures. According to the US EPA Document 40 CFR Part 503 (1999), the annual mi neralization rates of
18 the organic-N applied as biosolid are 30, 15, 8, 4, and 3% in years 1, 2, 3, 4, and 5, respectively in EPA region 8. However, these N-release patterns are expected to be accelerated in Florida where higher average annual precipitation and soil temperatures are more conducive of microbial decomposition (Wolf and Snyder, 2003). Correspondingly, Carrow and Johnson (1989) compared CRNS on centipedegrass ( Eremochloa ophiurides ) with ammonium nitrate (AN) and found under periods of active microbial grow th, Milorganite generated turf quality to AN. Controlled-Release Liquid N Sources in Turfgrass Liquid CRNS could be beneficial in the lawn care industry wh ich, for convenience, often applies fertilizers as a liquid. The chem ical char acteristics of these formulations vary, although differential microbial degradation of urea and reacted-N species provides the mechanism for extended N release. Landschoot and Waddington (1987) reported in itial turf response decreases relative to urea as the proporti on of water-insoluble N (WIN) in the formulation increased, and longer-chained methylene ureas were presen t. Carrow (1997), eval uated several ureaformaldehyde (UF) products and found Coron (50% N from urea, remainder polymethylene urea, methylene urea, monomethylol urea) and Nutralene (13% urea, 51% N from methylene polymers, 36% UF) induced lower average visual quality of bermudagrass ( Cynodon dactylon ) than urea. Splitting the N application into tw o equal treatments greatly improved long term response but at the expense of in itial and intermediate responses. In agreement, Sartain (2004) reported 37% of N applied as Nutralene was released in the first 7 d. However, in a separate study, Sartain (1992) found no bermudagrass qualit y, growth rate, or Nuptake differences between urea, Coron, and N-Sure (6% methylene diurea and methylol urea by weight, remainder 0.48 to 1.0 ratio triazone to urea) treated turf. Studies indicate reduced NH3 volatilization and N leachi ng are associated with urea-triazone products compared with urea and
19 AN (Clapp and Parham, 1991; Clapp, 2001). With inconsistent performance on warm-season grass, and no published studies documenting th e performance of CRNS on St. Augustinegrass, comparative information would be of interest to lawn-care professionals. Polymer-Coated Urea Fertilization in Turfgrass Polym er-coated urea (PCU) is a relatively new technology described by Goertz (1991). PCU releases N by osmotic diffusion through the polymeric coating, whereby coating thickness controls the release duration (Christianson, 1988). Field stud ies have shown PCU provides consistent release patterns within the desired window (Hummel, 1989; Peacock and DiPaola, 1992) and through the alteration of polymer chemistry and coating thickness can offer wide range of flexibility in N-releas e durations. Initially slow turf response and N-release have been observed compared to soluble-N sources (Carrow, 1997; Hummel, 1989; Sartain et al., 2004). Hence, soluble-N sources are sometimes include d in blends as bridgi ng products to provide increased initial responses (P eacock and Dipaola, 1992). Nevert heless, Hummel (1989) and Cisar et al. (2001) both reported increa sed N-uptake between 14 and 90 d post application relative to soluble N-sources at lower per-applica tion rates applied more frequently. Research Objectives Previous studies have observed differences in the perform ance of CRNS, although these distinctions appear to vary depending on tu rfgrass species and environment. Even though stringent restrictions have been imposed on lawn-g rass fertilization in Florida, few studies have evaluated CRNS on St. Augustinegrass under lawn maintenance regimes. Therefore, the objectives of the experiment were as follows. Objective 1: Determine if controlled-release N s ources applied under current regulatory restrictions can provide acceptable turf quality and density relative to urea.
20 Objective 2: Evaluate St. Augustinegrass response (i .e. quality, density, and N-uptake) in response to various N management regimes to de termine the most effective sources at each N application rate and frequenc y. Of particular interest was the longevity of turf response from CRNS applied prior to restrictive seasons at rates higher than currently permitted. Objective 3: Assess fertilizer response based on their broad categorizations by grouping sources across all rates to determine if quick -, controlled-release, or mixed component N sources provided the best St. Augustinegrass responses. Objective 4: Compare treatment effects on clipping yield under variab le N management using yield comparisons with th e lawn care industry standard, urea, to determine initial and long term response. Materials and Methods The field stu dy was replicated in space, and over two consecutive years at the University of Floridas, Fort Lauderdale Research and Education Center (FLREC) from April 30, 2007 to May 09, 2008 and May 10, 2008 to May 15, 2009 (hereafter each experimental period are denoted as 2007 and 2008, respectively) us ing St. Augustinegrass [ Stenotaphrum secundatum Walt. Kuntze] cv. Floratam. The climate in South Florida is subtropical, permitting warm-season grass growth year round, but varies seasonally as shown by data obtained from the Florida Automated Weather Network station located approximately 3 00 m from the experimental site (Appendix A). Traditionally, two distinct season s have been demarcated, the wet season (WS) from June to October, and the dry season (DS) from November to May, and our findings have been delineated in a similar manner to reflect climatic variation. The sand grown sod was established 6-mo pr ior on mined medium-fine sand (very coarse 0.2%, coarse 5.4 %, medium 29.9%, fine sand 62.9%, very fine sand 1.5%, and silt and clay 0.1%) having similar textural characteristics to the Margate and Hallandale fine sand series (Siliceous, hyperthermic Lythic Psammaquent) fo und in this coastal plain region. Composite soil samples from each plot were taken throughout the study (n = 4) from the 0 to 10 cm surface layer and analyzed by various procedures (A&L Laboratory, Pomp ano Beach, FL). Soil chemical
21 characteristics were averaged across the experime ntal period (Table 2-1) Due to high potassium (K) mobility in sandy soil, muriate of potash at 49 kg K ha-1 was applied every 3-mo. Bray P1 and Olsen Bicarbonate phosphorous (P ) extraction methods were used to determine soil P status, because of the potential for iron/aluminum-P co mplexes (under bio-solid fertility) and calcium (Ca)-P complexes under very high Ca inputs from irrigation (data not incl uded). Since additional P was supplied with biosolid (6-2-0) N applica tions and despite very high soil P status, an additional 24.5 kg P ha-1 was applied to all plots except th e BSD treatment on October 1, 2007 as triple super phosphate to ensure P was not limiting. Quantifiable visual or growth responses from this supplementary P application were not observed, so no additional P fertilizations were performed thereafter and it was assumed that extr action procedures accurately estimated soil P. Micro-nutrients were applied as Harrells Max Minors containing Mg 1%, S 3.5%, B 0.02%, Cu 0.25%, Fe 4%, Mn 1%, Zn 0.6% and Mo 0.0005% at 12.3 L product in 420 L water ha-1 every 90-d to ensure adequate tissue concentrations. The N sources descriptions, application rates, and frequencies are prov ided in Table 2-2. All treatments totaled 294 kg N ha-1 yr-1, which is within best management practice guidelines for St. Augustinegrass N fertilization in South Florid a (FDEP, 2008; Sartain, 2007). The controlledrelease liquid (CRL) treatments were applied in solution at 181 ml m-2 using a CO2 sprayer, equipped with two flat-fan TeeJet 8010 nozzles at 50 cm spacing. Granul ar sources were hand sprinkled. The irrigation system configuration (i .e. 2 plots per irrigation zone) permitted all treatments to be irrigated immediately follow ap plication to reduce volatil e N losses (Torello and Wehner, 1983). Irrigation was schedule 3 times per week delivering ~0.6 cm at each event, including post-treatment.
22 Visual Assessments Fertilizer response was evaluated in term s of visual field assessments of St. Augustinegrass quality, and density. Turf quality is defined as the degree in which turf conforms to an agreed standard, which is composition of uniformity, s hoot density, leaf texture, growth habit, smoothness and color (Krans and Morris, 2007). Turf density is a vi sual estimate of living plants per unit area (Morris, 2001). Visual quality ev aluations were conducted approximately every 14d on a one to nine scale in increments of 0.5; nine was dark green, dense turf, one represented dead, brown turf, and six was deemed minimally acceptable for all components (Carrow, 1997). Turf density was assessed less frequently, but in order to account for seasonal variations, ratings were conducted approximately every 90-d. St. Augustinegrass Tissue Harvest and Analysis Harvested clipping tissue provide d a basis for quantifying treatm ent effects on yield and N uptake. Clipping samples were harvested using a commercially available pedestrian rotary mower (Toro, Bloomington, MN) at a 7.5 cm height of cut. Mowing occurred weekly during the WS and bi-weekly during DS in both years. Clippings were removed as part of normal maintenance. Samples removed from the 2.24 m2 sub-plot units were oven dried at 60oC for 48 hrs to a constant weight. Yield represented average daily leaf dry matter production above 7.5 cm (Methall et al., 1983). Dried tissue was sub-samp led for analysis of tissue N content using the Kjedahl procedure (Wolf, 1982), with manual colormetric determination (UNIVO 2100, Dayton, NJ) of NH4-N according to Reardon (1966). Data were obtained according to quality assurance/quality control (QA/QC) protocol s set forth by Kennedy et al. (1994) where Nrecovery of standard reference materials 1573a and 1547 (National Institute of Standards and Technology) conformed to 89 to 101% of certificated values. Nitrogen upta ke, the product of N-
23 content (g N kg-1) and yield (kg dry wt. ha-1 d-1), was reported as g N ha-1 d-1 (Skogley and Sawyer, 1992). Statistical Design and Analysis The experim ent was conducted according to a randomized complete block design, with 2 x 4 m plots arranged with 3 replicates All data were tested for thei r conformity of the assumptions of analysis of variance (ANOVA) using PROC UN IVARIATE with normal plot of residuals and histogram of residuals (Clewer and Scarisbrick, 2001). Yield and relative N uptake data that did not conform were appropriately transformed based on the results of the Box-Cox transformation procedure (Box and Cox, 1964) befo re statistical analysis. Because N-sources and rates were not balan ced across all treatmen ts, Source x N-rate interactions was investigated separately for yield and N uptake parameters for appropriate sources (i.e. BS, CRL, a nd PCU at 49, 98, and 147 kg N ha-1 rates) and linear regressions were performed using the PROC REG procedure in SAS software (SAS Institute, 1999). All data were subjected to ANOVA using PROC GLM (SAS Institute, 1999) and mean separation was accomplished using single degree contrasts. Two-tailed F tests of error vari ance for the estimated parameters between years were performed so that means for corresponding cycles could be compared legitimately. Results and Discussion Comparisons of N Sources Base d on N-Release Categorization In Florida, much discussion has surrounded residen tial lawn fertilization practices. C ounty council debates have focused on broad categorizati ons of N fertilizers ba sed on their N-release mechanism (i.e. quickor controlled-release). For example, controlled-release N sources have been frequently referred to positively as havi ng less potential to leach N compared to quickrelease N fertilizers. However, little consid eration is given to the agronomic fertilizer N
24 responses of St. Augustinegrass under these broad N source categorizations. As such, it was considered appropriate to provi de comparative information of N-sources based on these broad categorization. Controlled-release N sources and mixed component N sources (MCNS) (i.e fertilizer blends containing equal N combinations of quickand c ontrolled-release N materials) were grouped in appropriate categories, and compared with th e quick-release N-source. Turf quality, density, yield, and N-uptake were affected by N-source categorization in 2007 and 2008 (Tables 2-3, 2-4, 2-5, 2-6). Urea, the only treatm ent composed exclusively from quick-release N produced greater turf quality than CRNS on 11 of 12 cycles th rough the 24-mo period. Sub-optimal climatic conditions for warm-season grass growth (Moore et al., 2004) during cycle 11 reduced turf quality across most treatments and potentially masked N-source effects. Nitrogen uptake followed a similar pattern. However unlike turf quality; elevated N-uptake from BSD and PCU at 147 kg N ha-1 reduced differences between N cate gories during cycle 1 and 7. Because appreciable improvements in turf quality were not observed in response to greater N-uptake relative to urea during the initial 60-d periods in the WS of 2007 and 2008, the elevated Nrelease from BSD and PCU at this higher N-rate may have detrimentally influenced the longevity of response from both sources. In both years, it is assumed that excessive initial N-release without correspondingly high improvements in tu rf quality resulted in lower N-uptake and quality ratings towards the latt er stage (cycles 3 and 9) of each 180-d WS release window (Tables 2-3, 2-6). These findings indicate that even with adva nced N-release technology (i.e. polymer-coating), the delivery of N over extended durations (i.e. 180-d) was less uniform than more frequent, lower per-application N-rates of quick-release ur ea in South Florida. The inability of CRNS to
25 deliver uniform N release throughout the entire release window may be a contributing cause of lower turf responses when compared to freque nt applications of qui ck-release N fertilizers. Nevertheless, ratings for the granular CRNS at these higher rates were all in the acceptable range and generally > 7. Conversely, when quick and cont rolled-release were combined as MCNS (i.e. UPCU1 and UPCU2) both turf quality and N-uptake were largel y indistinguishable from urea. This indicates that under reduced releas e durations (i.e. 60 to 120-d windows) the addition of soluble-N largely counteracts problems with inconsis tent N-release patterns. Differe nces were only apparent under cooler conditions in the DS, where quality ra tings and N-uptake were greater for urea during cycle 4 (2007). Despite the si milarity in terms of quality throughout 2008, N-uptake was lower for MCNS during cycle 12 (DS). Peacock and DiPaola (1992) made similar observations, suggesting polymer coating permeability, dissoluti on rate, and N-release decrease under lower temperatures. Therefore, in order to optimize N management from MCNS and combat slower Nrelease from PCU in response to cooler conditions lawn-care professionals may find it beneficial to increase the proportion of quick-release N in blended fertilizers intended for use under DS conditions in South Florida. However, care should be exercised to ensure increasing the soluble N-fraction of fertilizer blends are in compliance with local ferti lizer ordinances. Our study is in agreement with numerous studies (Landschoot and Waddington, 1987; Peacock and DiPaola, 1992; Carrow, 1997) that in most situations, CRNS in combination with quick-release N offer viable alternatives to freque nt applications of urea. Given the propinquity of St. Augustinegra ss response under quick-release and MCNS fertilization, it is not surprising that MCNS outperformed CRNS in terms of quality and Nuptake. However, under MCNS fertilization, N-uptake differences were manifested more slowly
26 between categorizes, with CRNS showing comparab le levels during cycles 1 and 2 (2007), even with the 50% soluble-N proportion in the blended fe rtilizers. Therefore, when initiating a MCNS program, initially the proportions of quickand co ntrolled-release N should be weighted toward the former, in order to induce notable plant respon se but could be reduced accordingly thereafter. In the context of this study, direct comp arison of quickversus CRNS may have been confounded by considerably lower measurable pa rameters in CRL plots over each N-rate and frequency. Nevertheless, turf dens ity assessed on individual rating dates every 3-mo, appeared to be less affected by the N-release mechanism (Tab le 2-4), demonstrating CRNS were capable of maintaining turf density equal to that of urea on 6 of 9 assessment s, despite lower ratings in the CRL treatment. It may be considered unfair to dr aw broad conclusions of the effectiveness of these N-release categories on St. Augustinegrass based solely on these findings. The author could find no other studies that have made direct agronomic response comparisons between fertilizers based on N-release cate gorization, but in order to addr ess the subject conclusively a great deal more N-sources in both ca tegories would have been needed. Comparisons of N Sources Applied at 49 kg ha-1 at 60-d Intervals Fertilizer treatments were divided into si x cycles per annum (Table 2-2). During 2007, PCU and BSD were slow to induce sati sfactory quality in cycle 1 (T able 2-3). Compared to BSD, lower N-uptake and yield in cycles 1 and 2 for PCU would indicate that the initial release patterns are slower for PCU (Table 2-6). Ther eafter, cumulative quality increases suggest residual N-release from preceding applications is sufficient to sustain adequate turf quality (Table 2-3). Examining N-uptak e from equivalent WS cycles in 2007 and 2008 provides further evidence that residual N-carryover plays an importa nt role in generating sufficient turf quality for PCU and BSD at this N-rate. Nitrogen uptake increased by 1.3 and 3.8 fold for BSD and
27 PCU, respectively during cycle 8 (2008) compared to cycle 2, similarly, both sources generated 2fold increases when cycle 9 was compared to cycle 3. Current mandates prohibit CRNS being applied at 49 kg N ha-1 every 60-d during the WS in certain Florida counties. The suppl y of residual N from preceding a pplications appears to be an important aspect for the effectiveness of BSD an d PCU at this N-rate and interruption of this process due to restrictive seasons may reduce the effectiveness of this N management approach. It appears improbable that eith er source would be capable of sustaining acceptable quality (i.e. quality 6) throughout a 120-d restrictive season with a single 49 kg N ha-1 application. Furthermore, because customer satisfaction depends on noticeable turf responses from applied fertilizer, the delayed initial responses particul arly from PCU, may limit the wide scale use of this N source and rate, unless PCU was blended with soluble-N. Quality differences between BSD and PCU were confined to cycles 6 and 7 where PCU delivered superior ratings (Table 2-3). Greater N-uptake for PCU in cycle 5-7 (Table 2-6) also resulted in greater yield, 78 and 116 % relative to urea in cycles 5 and 7, respectively compared to BSD where lower yield, 44 and 70 % were observed relative to urea in the same cycles (Table 2-5). Despite the 60-d application window corres ponding more closely with manufacturer recommendations for CRL (Georgia-Pacific, 2007), this product demonstrated lower turf quality, density, and N-uptake in both year s relative to BSD and PCU. In addition, the maximum yield was 55% relative to urea in both years (Table 2-5). These findings i ndicate this N-reaction product is less effective on St. Augustinegrass. Carrow ( 1997) reported reduced mowing requirements and visual quality from bermudagr ass treated with a similar UF reaction product compared to urea, however di fferences were less pronounced.
28 Urea maintained good mean turf quality throughout each cycle and was indistinguishable from the UPCU treatment. Compared with PCU and BSD, UPCU produced greater quality in cycles 2, 4, 6, 10, and 11 (Table 2-3). Elevated N-uptake was observed in cycles 2, 6, and 12, while yield differences were c onfined to cycles 2 and 4. Incr eased quality for UPCU without necessarily demonstrating highe r average N-uptake or yield may imply that more uniform delivery of applied N from the MCS may bene fit turf quality (Table 2-3, 2-5, 2-6). In contrast, N-source appeared to influence turf density to a lesser degree than quality, with UPCU demonstrating elevated levels on single rating dates in 2007 and 2008 (Table 2-4). Under adequate N fertilization turf density may be expe cted to fluctuate less th an quality, since color improvements (a major component of overall tu rf quality) are manifested more rapidly in response to available-N (Waddingt on et al., 1963). During each year, treatments that induced elevated quality also produced denser turf. Consequently, density ratings were generally lower for CRL, consistently below acceptable standards, and less than BSD and PCU on 8 of 9 rating dates (Table 2-4). For most sources, the annual N rate of 296 kg ha-1 yr-1 delivered acceptable turf density, as demonstrated by ratings of at l east 6.0. However, at this N-rate, which represents the upper annual N limit suggested by best management practice (BMP) guidelines (FDEP, 2008) and exceeds that of most local municipality ordinanc e restrictions, uniform high density (i.e. density 7.5) was not achieved, even with urea. While studying the effects of N-rate on bermudagrass density, Carrow et al. (1987) repor ted similar results indicating th at higher annual N-rates were required to achieve maximum turf density, althou gh as was the case in our study, clippings were collected during mowing and turf was grown on a low organic matter sand soil. Johnson et al. (1987) reported that recycling clippings enhan ced shoot density and may contribute up to 100 kg
29 N ha-1 yr-1. Under soil conditions similar to that obser ved in this study, higher N-inputs may be required to achieve maximum St. Augustinegrass de nsity in South Florida. In locations where legislation prohibits such actions, additional stipul ations may be needed to enforce the return of clippings to prevent large scale declines in turf density, a factor that has been shown to increase nutrient run-off (Gross et al., 1990; Linde et al., 1995, 1998; Easton and Petrovic, 2004). Comparisons of N Sources Applied at 98 kg ha-1 at 120-d Intervals The CRNS e valuated performed best under this 3 cycle per year regime, where cycles covered the WS and DS with a transitional cycle that stra ddle both periods. The 120-d application interval corresponded more closely with N-release patterns observed from PCU in previous studies (Fry et. al. 1993; Cisar et. al. 2001). Correspondingly, PCU outperformed other CRNS, generating turf quality and yield compar able to urea throughout the 24-mo study (Tables 2-3, 2-5). At this higher pre-ap plication N rate, delayed N-release was less apparent with PCU, demonstrating equivalent levels of N-uptake to quick-release N in the initial 60-d period. Therefore, as a lawn-care product, PCU (8% coati ng weight) is more suite d to this application rate and frequency, because cust omer satisfaction depends on no ticeable turf responses from applied treatments (Spangenberg et al., 1986). Polymer-coated urea delivered higher average quality ratings in cycles 2, 4, 6, 10, and 12 (Table 2-3) and demonstrated in creased yield and N-uptake in cycles, 2, 4, 6, 8, 10, 12 relative to BSD (Table 2-5, 2-6). It has alr eady been stated that response s from PCU decreased under the cooler, DS conditions. Nitrogen release from microbial dependent N-mineralization may be impacted to a greater degree in response to lowe r temperatures, since quality, density, yield, and N-uptake differences between sources were more a pparent during the DS in both years. Stanford et al. (1977) observed the fraction of N mineralized in relation to temperature and reported an ~ 40 % decrease in the rate of mineralization as average monthl y air temperature declined from 27
30 to 22oC; the mean average air temperatures in the WS and DS, respectively (Appendix A). Carrow et al. (1997) evaluated PCU (41-0-0) and Milorganite on bermudagrass at 98 kg N ha-1 under temperatures consistent with DS conditions, found reduced shoot growth for Milorganite 72 and 56% that of PCU in year 1 and 2, respectively. In agreement, we observed very similar results when BSD was compared to PCU (42-00), with 70 and 53% less yield in 2007 and 2008, respectively. In essence, the bio-available N from BSD may be released mo re slowly than the N from PCU. Consequently, turf quality, densit y, yield, and N-uptake were correspondingly lower for BSD, which is in agreement with Sartain et al. (2004) who demonstrated through incubation studies that PCU releases ~80% of applied N in 112-d versus only ~40% from Milorganite during a 180-d incubation period. The performance of CRL declined under the hi gher per-application N, reduced frequency regime. Turf quality only marginally exceeded mi nimally-acceptable standards (i.e. turf quality 6.0) during the WS in 2007 and thereafter remained consistently below this level. Comparisons of yield during the WS demonstrated inferior grow th from this source. For instance, CRL, BSD, and PCU induced average WS yields of 52, 82, and 93% in 2007 and 20, 74, and 132% during 2008, respectively compared to urea (Table 2-5) Moreover, when N-uptake was average over the WS of both years, CRL was the only source to demonstrate lower values in 2008 than 2007 (Table 2-6). Nitrogen uptake wa s quantified as a function of clipping yield. Minimal yield response following fertilization at 98 kg N ha-1 for CRL which corresponded to ~ 40 kg solubleN ha-1 in 2008 may be explained by substantial reductions in turf density (Table 2-4). In low density warm-season grass canopies, in creased assimilation of photosynthates in response to applied N may be channeled preferen tial towards lateral growth to increase stand density in preference to appr eciable biomass yield production for St. Augustinegrass. Low red
31 light (R) to far-red light (FR) ratios caused by FR reflected on green leaves, provide an environmental cue of the presence of neighboring pl ants (Ballar et al., 198 7). The extent of the reduction correlates with the pr oximity of surrounding vegetation (Smith et al., 1990) and reduced tillering in bunch growth type C3 gra sses (Casal et al., 1986, 1990). In contrast, under high R to FR ratios, as would occur in lo w density canopies, si gnals perceived by the phytochrome may induce tillering and through morphological plasticity enable stolon growth to increase turf density. In support, Frank and Hofman (1994) f ound that through defoliating grass canopies and increasing the R to FR ratio at the canopy base, increa sed stand density was achieved. In 2007, urea plus PCU (UPCU) outperformed CR NS, generating superior turf quality in cycles 1, 3, and 5 relative to PCU and BSD (Table 2-3). However, following an initially-superior quality response from UPCU in 2008, overall quality was more c onsistent for PCU and BSD and produced combined ratings superior to UPCU in cycles 8 and 10. Clippi ng yields from UPCU were for the most part undistinguishable from urea and exceeded that of PCU during the 60-d period following fertilization in cycles 1 and 5 (Table 2-5), presumably due to the quick-release portion stimulating more rapid growth. Yield improvements for PCU in 2008 followed a similar pattern to quality with greater yield observed in cycles 7 and 12, where PCU induced yield equal to urea compared to 40% less from UPCU in cy cle 12. Our findings sugges t that benefits of combining quick and controlled-release sources in 50:50 N proportions (i.e more rapid initial turf quality responses) are mainly observed during the first 12-mo period. Beyond this time frame, more uniform turf response and greater N-uptake from PCU suggests this source is more effective over a 120-d rel ease interval at 98 kg N ha-1 when applied solely in controlled-release formulation. Few studies have monitored the performance of CRNS con tinuously over extended
32 periods, largely because climatic conditions enfo rce relatively short growth seasons for warmseason grasses. In this instance, under year-round growth conditions, PCU applied at this N-rate and frequency provided continual improvement s in St. Augustinegrass lawn quality and N utilization with continuous use. Our long-term findings are contradictory to numerous studies (Landschoot and Waddington, 1987; Peacock and DiPaola, 1992; Carrow, 1997) whose shortterm conclusions indicate PCU sources are more effective when used in conjunction with soluble N. We conclude that under restri ctive N legislation, that PCU app lied solely as controlled-release fertilizer would be considered more environm ental judicious with reduced potential for NO3-N leaching and improved N-utilization comp ared to MCNS over the long-term. Comparisons within N Sources Applied at 147 kg ha-1 at 180-d Intervals The CRNS evaluated differed in their initial a nd long-term longevity of responses between years. CRL imparted acceptable turf quality for ~120 d and ~43 d, with acceptable turf quality apparent 9 and 20 days after treatments (DAT ) for 2007 and 2008, respectively (Fig. 2-1, 2-2). Growth and N-uptake also dropped sharply in the latter year for CRL, with average WS yield relative to urea of 67% in 2007 versus only 15% during 2008. When N-uptake was averaged over both WS periods a 44% reducti on was observed (Table 2-5). In previous studies involving various UF reaction products (Landschoot and Waddingtion, 1987; Carrow 1997), found sources th at provided good initial respons es were less effective over extended release durations. The 180-d release period far exceeded the 60 to 90-d re-application interval suggested by the manufacturer (Georgia Pacific, 2007), as such, turf density declined appreciable by the end of the each 180-d applic ation period, presumably through insufficient PAN throughout the latter stages of the extended N-release window. These findings highlight the importance of selecting CRNS that closely correspond to the intende d use criteria and that St.
33 Augustinegrass grown on sand soil, low in orga nic matter, requires continuous inputs of N during summer months in order to sustai n adequate turf qua lity and density. Conversely, PCU and BSD provided elevated durations of accep table turf quality in 2008 compared to 2007, although differences in initia l and long-term response were observed between sources (Fig. 2-1, 2-2). For instance, BSD produced initial turf quality responses similar to CRL during 2007, although BSD maintained acceptable turf quality far longer (~134 d). Following initial applications, improvement s in turf quality were slower from PCU in 2007, ~32-d were required to attain acceptable turf quality fo llowing fertilization, although overall response longevity was greater (~152 d) than other CRNS (Fig. 2-1). Yield and N-uptake for PCU averaged over each 60-d cycle reflected this sl ower initial N-release pattern, with increased Nuptake longevity in the final two cycles of each 180-d period in 2007. (Tables 2-5, 2-6). For PCU, higher turf quality pr ior to applications in the WS (2008) was beneficial. This provided a buffer in which to mask latent N-re lease permitting acceptable turf quality throughout the 180-d interval (Fig. 2-2). In 2008, BSD also delivered acceptable turf quality for the duration of the 180-d release window. When both WS periods were considered, the data indicates that if turf quality is reasonable prior to application, all CRNS evaluated at this N rate were capable of sustaining adequate turf quality for the 120d restrictive season im posed by certain local legislative bodies. Moreover, both PCU and BSD provided acceptable turf quality for longer durations (i.e > 120-d), partic ularly in 2008 (Figure 2-2), de noting the potential to reduce application rates to achieve desirabl e durations of la wn aesthetics. For BSD, initial responses were largely iden tical in both years and consistent with urea (Figures 2-1, 2-2), which is in agreement w ith Sartain (1999) who re ported Milorganite is composed of ~20% soluble N and therefore would deliver 29.4 kg ha-1 of PAN at this N rate.
34 Ironically, our findings indicate that in order to obtain noticeable fertilizer responses from St. Augustinegrass, a factor that is important in the lawn-care industr y, ~30 kg soluble-N ha-1 is required. Although this application rate is currently permitted under state labeling legislation in Florida, certain counties prohibi t this per-applicati on rate of soluble N (Board of County Commissioners of Sarasota C ounty, Ordinance No. 2007-63; Board of County Commissioners of Lee County, Ordinance Number 08-08; Board of County Commissioners of Charlotte County, Ordinance Number 2008028). Despite lower temperatures, greater improveme nts in turf quality together with higher average seasonal ratings were observed from BSD during the DS in 2007 and 2008. Quality ratings illustrated more uniform, extended releas e patterns indicating that N release from BSD (i.e., mineralization) is more ti ghtly coupled to plant demand. In other words, N release from BSD was more biologically driven while PCU was driven by the physical environment. These results suggest BSD applied under this extended regime appears more suited for dry season conditions in South Florida particularly during the initial year of use. Residual N carry-over from preceding cycles is also possible and may explain extended durations of acceptable turf quality during the WS in 2008. In agriculture, much emphasis is placed on applying biosolids at the agronomic rate to meet crop N requirements. Under Environmental Protection Agency (EPA) guideline s, land managers are directed to adjust application rates in subsequent years of use to account for latent N mineralization from the prior application (United States EP A Document 40 CFR Part 503, 1999). Under field conditions in Florida, He et al. (2000) found that 48% of the total organic N component of biosolids was mineralized in 12-mo and stated that the exte nt and rate of N mineralization needs to be considered carefully to minimize the risk of NO3-N leaching. Based on He et al. (2000) and
35 Sartain et al. (2004) who reported similar mineralization rates, we infer plant available nitrogen (PAN) would increase in response to repeat application of BSD a nd that measured turf responses should improve correspondingly over time with continual use. Several st udies in cool-season turfgrass research with the biosol id Milorganite, have reported these conclusions. Moberg et al. (1970) showed increased yield, color, and N r ecovery in the second year of evaluations. Waddington et al. (1976) reported to tal soil-N increased for Milorganite relative to synthetic CRNS, and increased yield resulted from continue d use in long-term evaluations. Hummel and Waddington (1981) also showed residual N effect s from both synthetic and natural organic fertilizers and hypothesized through continued use, performance of low-recovery N products can be expected to increase. On St. Augustinegrass, BSD compared less favorable to PCU especially under lower pre-application N rate s, applied more frequently. Long-term studies, similar to Waddington et al. (1976) and agricu ltural evaluations by Barbaric k et al. (1997) and Barbarick and Ippolito (2007) are required in warm-season turf grass research to help answer the following questions. How does PAN from BSD change with continuous application? Does N-rate and application frequency influence PAN over time? At what point does cumulative-N increase to the point that exceeds plant uptake and cause detrimental environmental implications? The Relationship between Controlled-release Nitrogen Rate and St. Augustinegrass Yield In order to deliver the sam e total annual N rate, application frequency differed between N rates that preordained two occasions (April 30, 2007 and May 15, 2008) when controlled-release sources were applied in unison at 49, 98, and 147 kg ha-1. N rate x yield inte ractions were only observed in 2007. Treatment induced differences in tu rf density prior to fe rtilizer applications may have influenced interactions in 2008. In the fi rst year, variation in yield can be explained by a linear regression model for each CRNS, with R2 values of 0.95, 0.98, and 1.00 for BSD, CRL, and PCU, respectively (Fig. 2-3). The data sugges ts that the maximum yiel d was not achieved for
36 each CRNS at 147 kg N ha-1 and for every 49 kg N ha-1 increase in fertilizer N rate you would expect an additional 0.06, 0.04, and 0.02 kg dry weight (DW) ha-1 d-1 yield increase in St. Augustinegrass under BSD, CRL, and PCU fertilization, respectively. However, making inferences outside the range of X-values used to find the fitted equations may generate erroneous results. For instance, a ma ximum yield is expected at a given fertilizer rate in excess of 147 kg N ha-1 and above that hypothetical rate, yield is expected to decline. Furthermore, the data only repres ents the initial 60-d period after fertilizati on, a factor that was limited due to re-application of sources on the 49 kg N ha-1 (60-d frequency). During the relative short period the full extent of N release may not have been realized, because each source was expected to release N for more extended periods a nd initial response distinctions were noted that undoubtedly influenced the slope, particularly for PCU with slow initial N release characteristics. Conclusions This study has shown that acceptable turf quality is possible with high frequency, low application rates of CRNS; howev er we found that lower frequenc y, higher application rates of m any CRNS produce better quali ty turf. Thus, limiting applic ation rates reduced optimal controlled-release performance with respect to tu rf quality, yield, and N-uptake. For instance, at current regulated rates imposed on controlled-r elease fertilizers in Florida, PCU and BSD provided acceptable quality St. Augustinegrass, albe it after an initial delay in response. The higher per-application rates, which exceeded current regulated rates, over more extended periods, resulted in better turf quality, particularly for PCU at 98 kg N ha-1 on a 120-d release interval. Seasonal performance differences were noted, whereby BSD exhibited enhanced responses during the cooler DS at 147 kg N ha-1 on the 180-d cycle. Even so, the CRNS evaluated were inadequate in terms of either initial or long term response relative to urea applied at 60-d intervals, although through conti nuous use, the residual N effect improved initial responses for
37 PCU and improved longevity for BSD. We found that all CRNS applied at 147 kg N ha-1 were capable of delivering acceptable turf quality for the 120-d restrictive season although adequate turf density and quality were required for CRL prior to application. Our findings indicated that controlled-release N in combination with soluble N (i.e. UPCU) offered a viable alternative to frequent applications of urea. The relativel y poor performance of several CRNS at high frequency, low rates compared to low frequency, hi gh rates suggest the need for further research to determine the influence of application rate on the fate of applied N from CRNS on St. Augustinegrass.
38 Table 2-1. Effect of fertilizer treatments on sel ected soil characteristics averaged over the 24-mo study period. TREATMENT SOIL CHEMIC AL CHARACTERISTICS OM pH CEC BRAY1-P HCO3-PK Mg Ca % cmolc kg-1----------------mg kg-1 ----------------BSD1 2.2 7.1 5.5 78.8 60.6 92.468.5 811.7 PCU1 1.9 7.1 4.5 62.6 45.3 86.152.7 694.0 CRL1 1.4 7.2 4.0 67.6 46.4 76.246.6 613.8 UPCU1 1.8 7.1 4.7 62.9 45.1 94.656.3 698.4 UREA1 2.1 7.1 5.3 63.2 46.0 91.263.0 798.9 BSD2 2.1 7.1 5.8 77.9 60.7 96.569.8 788.1 PCU2 2.1 7.1 4.8 67.1 50.1 86.460.3 712.1 CRL2 1.4 7.2 4.7 67.0 47.8 81.058.7 795.8 UPCU2 2.0 7.1 5.4 60.2 44.3 95.964.5 805.2 BSD3 2.0 7.1 5.3 80.5 58.5 94.167.0 778.2 PCU3 1.9 7.2 4.6 60.1 46.4 88.954.1 693.6 CRL3 1.4 7.2 4.7 68.0 45.9 81.356.3 798.7 MEAN 1.9 7.1 5.0 68.0 49.8 88.759.8 749.0 LSD0.05 0.4 NS 1.1 4.8 9.9 11.712.6 NS CV% 12.7 0.9 13.0 4.1 11.7 7.8 12.5 15.4 Average of four sampling instances taken prio r to and periodically during study period to a depth of 10 cm. LSD = Soil parameters are significantly differe nt if the difference between column means is greater than Fishers least significant difference test. NS = Not significant. Bray 1 extractable P (0.03 N NH4F + 0.025N HCL). Olsen extractable P (0.5 N NaHCO3 + 0.025N HCL) The numeric demarcation at follows each treatment code indicates N rate and application frequency; 1, 2, and 3 representing 49 kg ha-1 (every 60-d), 98 kg ha-1(every 120-d), and 147 kg ha-1 (every 180-d), respectively.
39 Table 2-2. Nitrogen source descript ion and application information. TRT PRODUCT DESCRIPTION N-P-K ANALYSIS N APPLIED APP. INTERVAL MANUFACTURER kg ha-1 days BSD1 Lawn grade sewage sludge biosolid 6-2-0 49 60 Milorganite, Miliwaukee, WI PCU1 Polymer-coated urea 42-0-0 49 60 Pursell Inc., Sylacauga, AL CRL1 12% Urea + 18% methylene urea + triazone 30-0-0 49 60 Georgia-Pacific, Decatur, GA UPCU1 50:50 N (urea:polymer-coated urea) 440-0 49 60 Pursell Inc. & PCS Sales, Inc Urea Granular 46-0-0 49 60 PCS Sales, Northbrook, IL BSD2 Lawn grade sewage sludge biosolid 6-2-0 98 120 Milorganite, Miliwaukee, WI PCU2 Polymer-coated urea 42-0-0 98 120 Pursell Inc., Sylacauga, AL CRL2 12% Urea + 18% methylene urea + triazone 30-0-0 98 120 Georgia-Pacific, Decatur, GA UPCU2 50:50 N (urea:polymer-coated urea) 440-0 98 120 Pursell Inc. & PCS Sales, Inc BS3 Lawn grade sewage sludge biosolid 6-2-0 147 180 Milorganite, Miliwaukee, WI PCU3 Polymer-coated urea 42-0-0 147 180 Pursell Inc., Sylacauga, AL CRL3 12% Urea + 18% methylene urea + triazone 30-0-0 147 180 Georgia-Pacific, Decatur, GA TRT = Treatment code: CRL = Control rel ease liquid; PCU = Polymer-coated urea; BS = Activated sewage sludge biosolid; UPCU = Urea in equal N combination with polymer-c oated urea. N source release window, sour ces reapplied following interval (days). The numeric demarcation at follows each treatment code indicat es N rate and application frequency; 1, 2, and 3 representing 4 9 kg ha-1 (every 60-d), 98 kg ha-1(every 120-d), and 147 kg ha-1 (every 180-d), respectively.
40 Table 2-3. The influence of N source, applicatio n rate, and frequency on average visual quality over 60-d cycles across 2007 and 2008. TREATMENT ST. AUGUSTINEGRASS QUALITY 2007 2008 WET SEASON DRY SEASON WET SEASON DRY SEASON C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 ------------------------RATINGS [1-9 SCALE] ------------------------BSD1 6.0 7.1 7.0 6.7 6.7 6.8 6.8 7.7 6.9 7.1 6.3 7.3 PCU1 5.7 7.5 7.3 6.9 6.8 7.7 .3 7.7 7.2 7.0 6.4 7.7 CRL1 5.4 6.4 5.7 5.7 5.0 5.7 5.6 6.5 5.7 6.0 5.6 6.1 UPCU1 6.8 7.6 7.4 7.3 7.5 7.7 7.5 7.6 7.1 7.9 6.9 7.6 UREA1 6.0 7.8 7.4 7.6 7.8 7.6 7.8 7.5 7.1 7.8 6.7 7.3 BSD2 6.3 6.8 7.4 6.3 6.9 6.5 7.4 7.2 7.5 7.2 6.0 6.6 PCU2 6.2 7.5 7.7 7.1 7.0 7.6 7.7 7.5 7.5 7.9 6.2 7.6 CRL2 6.3 6.6 6.5 5.4 5.7 5.4 5.9 5.6 5.9 5.3 5.2 5.6 UPCU2 6.9 7.4 8.0 6.7 7.6 7.3 8.0 6.9 7.7 7.0 6.4 6.7 BSD3 7.0 7.1 6.0 7.7 7.2 6.3 7.8 7.2 6.4 8.0 7.3 6.9 PCU3 6.5 7.8 6.6 6.7 8.0 7.3 7.9 7.4 6.2 6.6 8.0 7.7 CRL3 6.7 6.8 6.6 6.3 5.0 4.9 6.2 5.5 5.2 6.6 5.3 5.5 CONTRAST UREA vs. CRNS# *** *** *** *** *** *** ** *** *** NS ** UREA vs. MIXED NS NS NS ** NS NS NS NS NS NS NS NS MIXED vs. CRNS NS ** *** *** *** *** *** *** *** PCU1 vs. BSD1 NS NS NS NS NS ** NS NS NS NS NS CRL1 vs. BSD1 & PCU1 NS *** *** *** *** *** *** *** *** *** ** *** UPCU1 vs. PCU1 & BSD1 NS NS *** NS NS NS NS *** NS PCU2 vs. BS2 NS ** NS *** NS ** NS NS NS ** NS ** CRL2 vs. BSD2 & PCU2 NS *** *** *** *** *** *** *** *** ** *** UPCU2 vs. PCU2 & BSD2 NS NS NS NS NS NS PCU3 vs. BSD3 NS ** ** *** ** NS NS NS *** CRL3 vs. BSD3 & PCU3 NS ** *** *** *** *** *** *** *** *** *** *** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 60-d cycle. The numeric demarcation that follows each treatment code indicates N rate and application frequency; 1, 2, and 3 representing 49 kg ha-1 (every 60-d), 98 kg ha-1(every 120-d), and 147 kg ha-1 (every 180-d), respectively. Single degree contrasts performed at the alpha level 0.05. # CRNS: Controlled-release N sources (BSD, CRL, and PCU) grouped across all rates and frequencies. MIXED: Mixed component N sources (UPCU) grouped over both rates.
41 Table 2-4. The influence of N source, application rate, and frequency on vi sual density evaluated ~ every 3-mo across 2007 and 2008. TREATMENT ST. AUGUSTINEGRASS DENSITY 2007 2008 WET SEASON DRY SEASON WET SEASON DRY SEASON 04/29 07/31 10/30 01/29 05/09 08/08 11/07 02/20 05/15 ------------------------RATINGS [1-9 SCALE] ------------------------BSD1 4.7 7.0 5.0 6.7 7.0 7.3 6.3 5.0 6.5 PCU1 4.8 7.5 6.3 6.2 8.0 7.2 6.5 5.2 7.2 CRL1 5.0 6.5 4.0 4.8 6.0 6.5 5.2 4.2 4.2 UPCU1 4.8 7.5 6.3 6.7 7.5 7.3 7.3 5.7 7.2 UREA1 5.2 7.3 6.2 8.0 7.2 7.3 7.0 5.7 6.2 BSD2 4.8 6.7 6.0 6.5 6.3 6.5 7.0 5.0 5.3 PCU2 4.8 7.5 7.5 5.8 7.5 7.0 9.0 4.8 7.0 CRL2 4.8 6.5 5.0 5.3 5.5 5.3 4.8 4.0 3.8 UPCU2 4.8 7.2 7.5 7.2 6.8 6.5 7.0 5.2 5.7 BSD3 5.2 7.0 4.7 7.0 6.2 6.8 5.7 6.0 5.0 PCU3 4.8 7.7 5.7 7.3 7.2 7.0 4.8 8.2 6.7 CRL3 5.0 6.7 4.2 4.7 5.2 5.3 4.5 4.2 3.2 CV (%) 6.0 3.7 11.0 8.3 9.7 5.6 6.2 11.4 12.2 CONTRAST UREA vs. CRNS# NS NS *** NS ** NS NS NS UREA vs. MIXED NS NS NS ** NS NS ** NS NS MIXED vs. CRNS NS *** ** *** NS ** PCU1 vs. BSD1 NS NS NS NS NS NS NS CRL1 vs. BSD1 & PCU1 NS *** ** *** ** ** *** *** UPCU1 vs. PCU1 & BSD1 NS NS NS NS NS NS NS PCU2 vs. BSD2 NS *** ** NS NS NS *** CRL2 vs. BSD2 & PCU2 NS ** *** ** *** *** *** UPCU2 vs. PCU2 & BSD2 NS NS NS NS NS NS NS NS PCU3 vs. BSD3 NS ** NS NS NS NS NS *** ** CRL3 vs. BSD3 & PCU3 NS ** *** ** *** ** *** *** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Fertilization events followed visual assessment. The numeric dema rcation that follows each treatment code indicates N rate and application frequency; 1, 2, and 3 representing 49 kg ha-1 (every 60-d), 98 kg ha-1(every 120d), and 147 kg ha-1 (every 180-d), respectively. Single degr ee contrasts performed at the alpha level 0.05. # CRNS: Controlled-release N sources (BSD, CRL, and PCU) grouped across all rates and frequencies. MIXED: Mixed component N sources (UPCU) grouped over both rates.
42 Table 2-5. The influence of N source, applicatio n rate, and frequency on dry weight yield over each 60-d cycle across 2007 and 2008. TREATMENT ST. AUGUSTINEGRASS DRY WEIGHT YIELD 2007 2008 WET SEASON DRY SEASON WET SEASON DRY SEASON C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 ------------------------------------kg DW ha-1 d-1 ------------------------------------BSD1 2.8 9.2 3.9 0.5 0.4 0.9 8.3 12.2 7.8 0.5 0.3 2.2 PCU1 1.6 4.8 4.4 0.6 0.8 1.6 13.6 15.5 8.6 0.5 0.3 2.6 CRL1 1.4 3.9 1.1 0.2 0.5 0.2 1.1 3.5 3.0 0.3 0.2 0.6 UPCU1 2.1 9.1 6.2 1.0 0.8 1.9 12.6 14.6 9.0 0.6 0.3 2.5 UREA1 3.4 11.9 6.7 1.4 1.0 2.0 11.7 12.1 9.3 0.9 0.3 2.5 BSD2 3.5 5.7 6.3 0.7 0.7 0.5 10.2 6.3 7.7 0.5 0.2 1.1 PCU2 2.9 11.2 6.8 1.2 0.7 1.5 25.7 12.6 7.0 0.9 0.2 2.5 CRL2 2.7 4.9 2.4 0.3 0.3 0.2 1.6 2.1 2.8 0.2 0.2 0.3 UPCU2 5.4 8.8 9.1 1.3 1.4 1.3 16.6 7.3 8.2 0.7 0.3 1.1 BSD3 6.4 9.5 1.7 1.0 0.7 0.6 22.4 10.7 4.3 1.1 0.4 0.8 PCU3 4.8 20.0 4.3 0.4 1.8 2.2 39.4 16.7 5.1 0.5 0.5 2.6 CRL3 4.5 6.2 1.2 0.4 0.2 0.3 1.6 1.9 1.5 0.5 0.2 0.3 CV (%) 19.0 14.4 17.2 18.4 17.9 24.5 16.7 16.8 7.9 15.3 11.3 13.0 CONTRAST UREA vs. 49 Kg RATE# ** ** *** NS NS ** ** PCU1 vs. BSD1 NS NS NS NS NS NS NS NS NS NS CRL1 vs. BSD1 & PCU1 NS NS *** NS NS ** *** *** *** NS NS *** PCU1 vs. UPCU1 NS NS NS NS NS NS NS NS NS NS UREA vs. 98 Kg RATE NS NS ** NS ** NS ** *** *** PCU2 vs. BSD2 NS ** NS NS *** NS NS *** CRL2 vs. BSD2 & PCU2 NS *** ** *** *** *** *** NS *** PCU2 vs. UPCU2 NS NS NS NS NS NS NS NS *** UREA vs. 147 Kg RATE NS *** *** NS ** NS NS *** NS NS *** PCU3 vs. BSD3 NS ** ** *** *** ** NS NS ** *** CRL3 vs. BSD3 & PCU3 NS *** NS *** ** *** *** *** *** *** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 60-d cycle. The numeric demarcation that follows each treatment code indicates N rate and application frequency; 1, 2, and 3 representing 49 kg ha-1 (every 60-d), 98 kg ha1(every 120-d), and 147 kg ha-1 (every 180-d), respectively. Single degree contrasts performed at the alpha level 0.05. # 49 kg RATE: Single degree contr ast of urea vs. all sources applied at 49 kg N ha-1. 98 kg RATE: Single degree contrast of urea (49 kg N ha-1) vs. all sources applied at 98 kg N ha-1. 147 kg RATE: Single degree contrast of urea (49 kg N ha-1) vs. all sources applied at 147 kg N ha-1.
43 Table 2-6. The influence of N source, applica tion rate, and frequency on nitrogen uptake over each 60-d cycle across 2007 and 2008. TREATMENT ST. AUGUSTINEGRASS NITROGEN UPTAKE 2007 2008 WET SEASON DRY SEASON WET SEASON DRY SEASON C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 ---------------------------------------g N ha-1 d-1 ---------------------------------------BSD1 47 204 81 10 9 21 172 269 163 11 5 41 PCU1 25 85 86 14 18 32 265 324 176 12 5 49 CRL1 19 69 17 4 8 4 18 67 52 6 3 10 UPCU1 32 177 117 19 18 40 244 292 193 14 6 47 UREA1 55 249 121 33 20 27 216 256 195 19 6 46 BSD2 59 103 133 12 14 9 206 116 172 10 4 19 PCU2 57 231 145 24 15 33 601 257 151 19 4 47 CRL2 40 81 41 5 6 4 25 33 52 4.1 4 5 UPCU2 103 156 193 24 32 27 337 128 193 16 5 18 BSD3 125 182 26 24 13 10 496 201 71 28 8 14 PCU3 109 497 72 8 42 47 958 356 90 13 12 44 CRL3 76 92 18 8 3 3 27 301 24 10 3 4 CV (%) 19.4 7.3 9.8 20.7 18.7 18. 6 9.2 7.0 3.8 12.1 18.1 9.1 CONTRAST UREA vs. CRNS# NS ** ** *** *** NS ** *** ** NS *** UREA vs. MIXED NS NS NS NS NS NS NS NS NS NS MIXED vs. CRNS NS NS *** *** *** *** ** *** NS *** PCU1 vs. BSD1 NS NS NS NS NS NS NS NS CRL1 vs. BSD1 & PCU1 NS NS *** NS *** *** *** *** ** NS *** UPCU1 vs. BSD1 & PCU1 NS NS NS NS ** NS NS NS NS NS PCU2 vs. BSD2 NS NS NS ** NS NS *** CRL2 vs. BSD2 & PCU2 NS *** ** *** *** *** *** *** NS *** UPCU2 vs. PCU2 & BSD2 NS NS NS NS NS NS NS NS NS PCU3 vs. BSD3 NS ** ** ** ** *** NS NS NS ** NS *** CRL3 vs. BSD3 & PCU3 *** ** NS *** *** *** *** *** ** *** *** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 60-d cycle. The numeric demarcation that follows each treatment code indicates N rate and application frequency; 1, 2, and 3 representing 49 kg ha-1 (every 60-d), 98 kg ha1(every 120-d), and 147 kg ha-1 (every 180-d), respectively. Single degree contrasts performed at the alpha level 0.05. # CRNS: Controlled-release N sour ces (BSD, CRL, and PCU) grouped across all rates and frequencies. MIXED: Mixed component N sources (UPCU) grouped over both rates.
44 Fig. 2-1. The duration of acceptable St. Augustinegrass quality (i.e ratings 6) provided by CRNS applied at 147 kg N ha-1 prior to the 4-mo rainy season fertilization on April 30, 2007. Vertical dashed lines indicate re strictive season parameters. Urea at high frequency, low per-application N provided a quality benchmark to assess initial and the long term response from CRNS. Arrows indicate urea fertil ization events. 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 4/295/95/195/296/86/186/287/87/187/288/78/178/279/69/169/2610/610/1610/2RATING DATESQUALITY RATING CRL3 PCU3 BS3 UREA1 MIN. ACCEPT. STD.
45 Fig. 2-2. The duration of acceptable St. Augustinegrass quality (i.e ratings 6) provided by CRNS applied at 147 kg N ha-1 prior to the 4-mo rainy season fertilization on May 15, 2008. Vertical dashed lines indicate re strictive season parameters. Urea at high frequency, low per-application N provided a quality benchmark to assess initial and the long term response from CRNS. Arrows indicate urea fertil ization events. 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 5/95/236/66/207/47/188/18/158/299/129/2610/1010/211/7RATING DATESQUALITY RATING CRL3 PCU3 BS3 UREA1 MIN. ACCEPT. STD.
46 y = 0.0598x 1.995 R2 = 0.9453 y = 0.0357x 0.4994 R2 = 0.9985 y = 0.0239x + 0.1562 R2 = 0.9845 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 457095120145NITROGEN RATE (kg N ha-1)YIELD (kg DW ha-1) BSD CRL PCU Linear (BSD) Linear (PCU) Linear (CRL) Fig. 2-3. The relationship between CRNS rate (i.e. 49, 98, 147 kg N ha-1) and average St. Augustinegrass yield during the 60-d period following initial fer tilization in 2007.
47 CHAPTER 3 INORGANIC NITROGEN LEACHING FROM ST AUGUS TINEGRASS IN RESPONSE TO NITROGEN FERTILIZATION STRATE GIES UNDER RESIDENTIAL LAWN CONDITIONS Introduction Anthropogenic intrusion to the magnitude experi enced in Florida in recent years has the potential to drastically alter th e nitrogen (N) cycle and more than double the production rate of reactive N (Galloway and Cowling 2002; Galloway et al. 2004). For example, increasing human population densities in various watersheds have been correlated with nitrate (NO3-N) degradation of groundwater (Vit ousek et al., 1997; Peierls et al., 1991), with detrimental consequences to ecological systems (Wolfe and Patz, 2002). Human health may also be impacted due the reliance on groundwater for drinking supplies, must not exceed the Maximum Contaminant Level (MCL) of 10 mg L-1 as N set by Environmental Protection Agency (EPA). Residential landscapes have increased dramatically in Florida in unison with urban development to support population expansion (Haydu and Cisar, 1990). St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is the predominant vege tation in Florida residential landscapes (Erickson et al., 2005) with an estimated land use of 810,000 ha (Trenholm and Unruh, 2007). Routine fertilization practices of residential turf grass have been implicated as a major source of NO3-N contamination of groundwater in these loca tions (Flipse et al., 1984). Urban fertilizer usage has increased in tandem w ith residential landscape expansi on in Florida (Erickson et al., 2005) and detailed evaluations of N fertilization strategies on St. A ugustinegrass are needed, particularly in South Florida where the most populated areas are lo cated throughout coastal regions where fine sand soils are subjected to frequent and intense se asonal precipitation ( McCollum et al, 1978; McCollum and Cruz, 1981; Pendleton et al. 1984; Hurt et al., 1995).
48 Environmental precursors in southern Florida are highl y conducive of rapid N leaching (i.e. coarse textured soil with high soil-water percolation) under conditions of excessive N fertilization coupled with abundant precipitation or irri gation (Reike and Ellis, 1974; Snyder et al., 1984; Morton et al., 1988; Barton et al., 2006). In efforts to address concerns over N loss from residential landscape N fertilization and to more effectively manage urban coastal watersheds influenced by non-point source pollutants, state-wide fertilizer labeling legislation was introduced. Directed specifically at reside ntial and urban landscapes, this legislation limits per-application N rates to 49 kg ha-1 and restricts the water-s oluble N portion to 34 kg N ha-1 (Department of Agricultural a nd Consumer services, No. 4640400, Rule 5E-1.003, 2007). In addition, certain coastal counties and munici palities imposed further prohibitive measures by restricting N fertilization duri ng the traditional rainy season in Florida from June 1 through September 30; constrains annual fertilizer N to 196 kg ha-1, and controls the soluble-N fraction to 24.5 kg N ha-1 per-application (Council of th e City of Sannibel, Water Resources Department, Ordinance No. 07-003; Board of County Commissioners of Sa rasota County, Ordinance No. 2007-63; Board of County Commissioners of Lee County, Ordinance No. 08-08). The scientific literature suggests that minima l N leaching or run-off occurs from judicious fertilization of established turfgrass with quick-release N-so urces (Easton and Petrovic, 2004; Gross et al., 1990, 1991; Linde et al., 1995, 1998; Miltner et al., 1996; Mosdell and Schmidt, 1985; Petrovic et al., 1986; Starr and De roo, 1981; Snyder et al., 1981, 1984), although appreciable N leaching has been observed when exce ss N fertilization on coarse textured soils is coupled with high irrigation or precipitation ( Barton et al., 2006 ; Nelson et al., 1980; Reike and Ellis, 1974; Snyder et al., 1984). Several st udies have indicated that NO3-N leaching is significantly reduced under controlledversus quic k-release N fertilization strategies (Brown et
49 al., 1977; Nelson et al., 1980; Snyder et al. 1981, 1984; Petrovic et al., 1986; Geron et al., 1993; Engelsjord and Singh, 1997; Guillard and Kopp, 2004) Of these, only Petrovic et al. (1986), Geron et al. (1993), and Guillard and Kopp, (2004) conducted their studies to address residential lawn fertilization under the cool-season grass co nditions. In fact, no pr ior study to date has examined the influence of quickand contro lled-release N-sources on N leaching from a conventional St. Augustinegrass lawn environment. Imposing stringent N application rate restri ctions unilaterally across all N-sources may negate the best features of c ontrolled-release nitrogen sources (CRNS). They are more effective when applied at infrequent higher per-appli cation rates (Skogley and King, 1968; Hummel and Waddington, 1984; Williams et al., 1997), which decreases water use in St. Augustinegrass (Subhrajit and Trenholm, 2005), and reduced N-spec ies leaching (Brown et al., 1977; Nelson et al., 1980; Snyder et al. 1981, 1984; Petrovic et al., 1986; Engelsjord and Singh, 1997; Guillard and Kopp, 2004). Current legislation prohibits higher per-applicati on rates of CRNS prior to the 120-d restrictive seasons, although th ese sources may provide sustained growth and vigor due to extended N-release patterns. There is considerable interest in determining whether higher preapplication rates of CRNS fertilizers induce appreciable N le aching under St. Augustinegrass lawn conditions. Consequently, research to investigate N-leaching under varying N sources, application rates, and frequencies on St. Augus tinegrass is of primary importance to better understand the efficacy of N rate regulation a nd provide legislative bodies with valuable information so that future enactments advocate sound agronomic and environmental principles. Research Objectives Numerous studies that evaluated N-leachi ng under cool-season residential turfgrass conditions have reported that environmental impa cts of N fertilization are reduced when CRNS
50 strategies are compared to qui ck-release soluble N approaches. However, to date no published studies are available under St. Augustinegrass lawn conditions. Therefore, the objectives of this experiment were as follows. Objective 1: to determine if controlled-release N sources can be applied at higher rates than currently permitted prior to restrictiv e seasons without negatively contributing to groundwater N degradation. Objective 2: to evaluate whether N leaching losses are escalated when the soluble portion of applied N is increased from cu rrently mandated levels of 24.5 kg N ha-1 to 49 kg N ha-1. Objective 3: to ascertain if variable N management approaches result in differences in N species leached. Objective 4: to establish if total N recovery wa s influenced by N management regime, using a N budget approach. Materials and Methods The experimental design, treatments, and st atistical analysis were described in the materials and methods section in chapter two (p 20), this section will focus on methodology pertaining to inorganic N leaching determinati ons. For a statistical standpoint, the only distinction between chapters was the occurrence of outliers. On two occasions, for urea and CRL 3 outliers were identified as datum that exceeded three standard deviations from the mean and were subsequently removed from analysis. Unfortunately, an appreciable amount of water samples were inadvertently discarded while awaiting analysis at FLREC. This constitute d samples from November 7, 2007 to January 6, 2008, and in terms of applicati on cycles corresponded to the be ginning of the dry season (DS) sampling period when 49 and 147 kg N ha-1 treatments were initially applied in cycle 4 and 2, respectively. Furthermore, this impacted half of the third cycle for 98 kg N ha-1 treatments. As such, leaching data for these full cycles are not presented.
51 Construction Specifications of the Field-Based N Leaching Facility A pre-existing elevated facility to permit gravity-fed water percolate collection was used for this experiment and since this facility has not been previously describe d a detailed account of construction specifications are pr ovided. In November 2004, ~ 400 m3 cubic meters of native soil was extracted allowing the installation of underl ying hard fractured limestone fill base for structural support. The foundation was laser-gra ded to provide a uniform base on which to construct an artificial soil profile throughout the 27.5 x 14 m site that corresponded to the constructed profile in each lysime ter; designed to facilitate quantifiable water percolation with minimal risk of flow restriction due to sand migration. Each lysimeter was constructed from a high de nsity polyethylene drum that was 86 cm long, an interior of 55 cm, a 1.3 cm thick wall, (US Plastic Corp., Lima, OH) and the flat bottom was removed. When installed the lysimeter was inverted so that the manufactured threaded aperture (to allow attachment of a liquid extraction device ) was situated at the base. Polyvinyl chloride (PVC) drainage pipes (schedule 40, 1.9 cm diam eter) were individually installed into the foundation with sufficient gradient to permit gravity-fed flow to the percolate collection sites located at the periphery of the facility. Drainage PVC pipe was connected to each lysimeter with a screw in PVC fitting, attached to a 90o elbow. A stainless steel screen (1 mm mesh) was inse rted into each lysimeter drainage outlet to retain the gravel (>14 mm 1%, 12-14 mm 7.5%, 9-12 mm 10.5%, 6.73-9 mm 28%, 6-6.73 mm 41%, 4-6 mm 7%, 2-4 mm 3.5%, <2mm 1.5%), whic h was back-filled to a depth of 10 cm. Medium sand (>2 mm 0.1%, 1-2 mm, 7.6%, 0.5-1.0 mm 26%, 0.25-0.5 mm 45.6%, 0.15-0.25 mm 19.1%, 0.053-0.15 1.2%, <0.053 0.6%) was uniformly positioned to a depth of 5 cm between the gravel layer and the finer root zone sand to act as a choker layer to prevent particle migration. Mason sand (very coarse 0.2%, coarse 5.4 %, medium 29.9%, fine sand
52 62.9%, very fine sand 1.5%, and silt and clay 0.1%) that closely matched the particle size distribution of the Margate and Hallandale fine sand soil series (Siliceous, hyperthermic Lythic Psammaquent) found in this coas tal plain region was back-fille d, and uniformly compacted at ~15 cm depth increments. The soil profile at the experimental site was constructed to conform exactly to lysimeter specifications before an additio nal 5 cm of mason sand was inst alled above the upper rim of each lysimeter to provide a final mason sand depth of 76 cm. The elevated rectangular platform was re-leveled and the sloping sides were gently gr aded to facilitate grass mowing maintenance. Sampling stations with sufficient capacity to contain three 20 L percolat e collection containers were excavated and supported with timber framing. An automatic irrigation system was configured to provide watering flexibility with individual irrigation zones covering 4 x 4 m unit areas (i.e. 2 treatment plots per irrigation zone). Each zone was fitted with landscape 1800 series pop-up sprinklers with 12 Series VAN, 15 Trajectory, 90o arc nozzles (Rain Bird Corp. Azusa, Ca) at each corner. In November 2006, 6-mo prior to the initia tion of our experiment, the existing sod was removed and mason sand matching the original speci fications was used to re-construct the initial soil profile specification, before St Augustineg rass cv. Floratam sod, harvested from sand grown soil was installed. Establishment fertilization included 49 kg P ha-1 from triple super phosphate and 49 kg K ha-1 from muriate of potash on January 12 and April 20, 2007. No N fertilizer was applied until trea tment initiation on April 30, 2007. Percolate Sampling and Field Quality Assurance Percolate drainage samples were collected ~every 7-d or following precipitation events exceeding 0.64 cm in accordance with Florida Depa rtment of Environmental Protection (FDEP) quality assurance/quality control (QA/QC) protocol that st ipulate appropriate collection of
53 blanks, duplicates and standards during field sa mpling. Sampling occurred more frequently for the 21-d periods following N fertilization when precipitation of 0.25 cm prompted sampling. Percolate water volume was recorded on each occasion. Sub-samples were collected in polyethylene scintillation vi als, stored on ice at 4oC during the sampling procedure, and stored in a frozen matrix until analysis. The N concentrat ion of irrigation water was determined at each sampling event and precipitation N was periodically assessed throughout the study period. Percolate Water Sample Analysis and Laboratory Quality Assurance Leachate samples were analyzed at FLREC for NO3-N and NH4-N using colorimetric methods G-200-97 Rev.3 and G-171-96 Rev. 8, respect ively (Seal Analytical, Norderstedt, Germany). Leachate data were subjected to strict QA/QC protocols. Colorimetric NO3-N and NH4-N calibration curves achieved r2 0.9995, while blanks, spikes, duplicates, and certified standards were 5% of expected values. In or der to achieve consistent spike recoveries, the minimal detection limit (MDL) was increased to 0.05 mg l-1 and 0.03mg l-1 for NO3-N and NH4N, respectively and sample concentrations determ ined below these levels were reported as MDL values, therefore, N leaching data are cons idered to be worst case scenario. The dual channel instrument permitted simultaneous analysis of NO3-N and NH4-N, however, the significant amount of time saved ca me at the expense of accurately determining NO3-N. The G-200-97 method relies on the reduction of NO3-N to nitrite (NO2-N) for colorimetric detection. Since NO2-N concentrations should be es tablished under a system devoid of cadmium reduction capacity a nd would be subtracted from NO3-N to accurately depict the concentration of NO3-N, this study reported inorganic-N leaching as NOx-N and NH4-N. Mean cycle flow-weighted NOx-N concentrations data, calculated as the total NOx-N leached divided by total percolate volume were presente d by fertilization cycle. To demonstrate the influence hydrological factors may contribute to increased instances of groundwater pollution
54 through excessive N leaching, individual NOx-N leaching events were plotted with precipitation data (summed over each sampling period) during pe riods when peak NOx-N concentrations were observed. Mean N loading data, calculated as the inorganic-N concentr ation divided by the surface area of the lysimeter, we re summed over each fertilization cycle to convey the potential for fertilizer N strategies to contribute to specific water body impairment. In coastal watersheds, where residential land-use has been estimated, this information may prove particularly pertinent since ground water delivers the majority of non-point source, land derived-N pollutants to estuaries and coastal ecosystem where N is of ten the limiting nutrient for growth (King and Balogh, 2008). In addition, the inorganic N inputs were summarized in budget format and aligned with N recovered in leachates and St. Augustinegrass tissue over each fertilization cycle to illustrate the efficacy of fertilizer N-strategi es and to divulge potenti al N losses or sinks not measured in this study. Results and Discussion Flow-Weighted NOx-N Concentrations Influenced by N Source and Hydrology During this study, N source influenc ed mean cycle flow-weighted NOx-N concentrations with highest concentrations occurring under urea fe rtilization, applied solely or in combination with polymer-coated urea (PCU) (i.e. urea plus PCU at 98 kg N ha-1 [UPCU2]) at soluble N rates of 49 kg ha-1 during the wet season (WS), 2007. When aver aged per fertilization cycle maximum NOx-N concentrations for urea were 6.4 and 3.1 mg L-1 in cycle 1 and 2, respectively (Table 31). For UPCU2, greatest con centrations occurred duri ng the same period with NOx-N concentrations of 10.5 mg L-1 (Table 3-2). In subsequent cycles, NOx-N concentrations from soluble-N sources were greatly reduced and despite a similar trend, whereby elevated concentrations from urea and UPCU2 occurr ed during the initial 60-d period following fertilization during the WS of 2008, no differences between so luble-N and CRNS were observed.
55 In 2007, NOx-N leaching was closely coupled with hydrological factors. Two intense precipitation events occurred shortly after fertiliza tions and appeared to coincide with peak NOxN concentrations. The first produced 60 mm and resulted in high initial NOx-N concentrations from urea (82.4 mg L-1) and UPCU2 (237.0 mg L-1), 17 days after fertili zation (DAF) (Fig. 3-1). The second 85 mm precipitation even t occurred 6 DAF of 49 kg N ha-1 sources, produced no additional losses from UPCU2, but induced further NOx-N concentrations of 28.6 mg L-1 from the urea treatment (constituting a 3-fold reduction in leachate NOx-N concentrations compare to cycle 1). The lower NOx-N concentrations from urea under greater preci pitation-induced leaching conditions may indicate increased capacity for St. Augustinegrass to capture and utilize applied N as the summer progressed. On the othe r hand, it may indicate that insufficient time had elapsed for complete transformation of urea to NH4-N, through enzymatic urease induced hydrolysis (Conrad, 1942) and subs equent nitrification of NH4-N to NO3-N (Harper and Boatman, 1926). Sarigumba and Fiskell (1976) conducted urea transformation studies under sandy soil conditions in Florida and reported the majority of urea hydrolysis occurred within 3-d under Blichton fine sand soil conditions, whereas Erik sen and Kjeldby (1987) reported that 85% urea hydrolysis rate after 4-d. Sabe y et al. (1956) illustrated thro ugh temperature based incubation studies that nitrification increases linearly with temperature and that the bulk of ammonium sulfate was nitrified within 7d at soil temperatures of 25oC (lower soil temperatures than observed in our study, Appendix A). Sartain et al. (2004) re ported the presence of NO3-N in leachate from incubated isobutylidene diurea (IB DU) after 7-d; a source that depends on an additional stage of water hydrolysis for urea release.
56 Noticeably higher NOx-N levels were collected in the leachate, 28.6 mg NOx L-1 compared to 7.8 mg NH4 L-1 (data not included) over this 6-d period in 2007 and the cation exchange capacity (CEC) of the soils was low (~3.2 cmolc kg-1). Therefore, we conc lude that appreciable nitrification had occurred and th at St. Augustinegrass was better ab le to recover applied N, even though climatic conditions were more conducive of rapid N-leaching following the second 49 kg N ha-1 urea application. These findings, together w ith leachate data from successive cycles demonstrating negligible losses of NOx-N despite substantial prec ipitation events in close proximity to fertilization (Tables 3-1, 3-2), s uggests the capture and ut ilization of applied N increases towards the latter stages of the summer growing season. Considering that the St. Augustinegrass sta nd was established 180-d prior to treatment initiation during the dry season (DS), in which lower temperatures and photoperiods were less conducive of growth, together with no N inputs during the establishment period, we believe the root system had not fully developed during the in itial stages of the experiment. DiPaola et al. (1982) described distinct seasona l rooting pattern s for St. Augustinegrass, noting that aggressive root initiation and growth during summer months was greatly re duced under cool er winter soil temperatures. Enhanced root grow th is associated with increased plant available nitrogen (PAN), namely in the form of root length. Although the root to shoot dry weight ratio declines with elevated N supply, the more highly branched, fi ner root structure increases surface area and nutrient acquisition (Marschner, 2002). Bowman et al (1998) repor ted that greater N accumulation and lower N leaching resulted from d eeper rooted creeping bentgrass genotypes. In greenhouse studies, Bowman et al. (2002) demonstrated that compared to six warm-season grass varieties, St. Augustinegrass possesses inherently greater root length density (RLD) and theorized that this morphological ch aracteristic resulted in lower NO3-N leaching. In essence,
57 under N deprived conditions during establishm ent, RLD progressively increased for St. Augustinegrass under adequate PAN during summer months. The pulse of NOx-N remained in contact with the deeper root system for longer durations and resulted in reduced NOx-N leaching as the WS progressed. Consequently, given the relationship between N fertility and root growth it appears plausible that restrictive fertilizer ordi nances (June October), may negatively impact root development during WS months, when optimal root growth ha s been observed for St. Augustinegrass systems. For example, during early summer 2007, when the root system of St. Augustinegrass may not have fully developed, we observed NOx-N in concentrations in excess of MCL standards (~13 mg L-1) in leachates following a UPCU1 a pplication (i.e. 24.5 kg soluble N ha-1), which corresponds to currently mandated N fertility guidelines for residential lawns (Fig. 3-3). It appears that N losses that exceed MCL standard s are possible, even under stringent soluble N level control, if significant precipitation events are encount ered shortly after fertilization. Ironically, the unintended consequences of fer tilizer legislation ma y result in greater NO3-N leaching, once fertilization resumes, if RLD is adversely affected by 120-d periods when N inputs are constrained. More res earch is required to better und erstand the physiological and morphological changes that occur in St. Augustin egrass in response to in tervals of severe N limitation in order to better understand the e fficacy of restrictiv e season legislation. Our findings indicating NOx-N losses in excess of MCL sta ndards are possible with soluble N fertilization in conjunction with intense preci pitation. However, these losses tend to decline over time, possibly indicating that N uptake efficiency improves concomitantly with successive fertilization. Conversely, judici ous use of CRNS prior to restri ctive seasons presented no such risk, which is consistent with numerous other studies (Petrovic et al 1986, Geron et al. 1993;
58 Guillard and Kopp, 2004), and would provide N for extended durations (Carrow, 1997; Hummel, 1989; Landschoot and Waddington, 1987; Moberg et al., 1970; Peacock and DiPaola, 1992; Volk and Horn 1975), to supplement root growth. Under CRNS fertilization, minimal NOx-N was leached and aver age cycle flow-weighted NOx-N losses were for the most part were 1.0 mg L-1 per cycle (Tables 3-1, 3-2, 3-3). Leachate NOx-N concentrations in excess of MCL were not observed from biosolid (BSD) or PCU applied at 147 kg N ha-1 throughout the 24-mo study period and were largely restricted to MDL values (Fig. 3-4, 3-5). These findings are consistent with numerous studies whose conclusions were drawn from diverse locations and grass varieties. Barton et al. ( 2006) investigated the influence of N source fertilization and irrigation during a 22-mo turfgr ass production study with four warm-season grass vari eties, reporting NO3-N concentration in percolate from polymer-coated N or biosolid treatments never exceeded MCL standards, even when applied at 400 kg N ha-1 under high irrigation (i.e. 140% evapotranspiration). Brown et al ., (1977) under similar study parameters, showed that FWNC of < 3 mg l-1 resulted from what was considered high N rates (146-244 kg ha-1) of Milorganite on bermudagrass turf grown on sandy soil under high irrigation regimes. Guillard and Kopp (2004) demonstrated that a mixed species cool-season lawn turf fertilized with either polymer-coated sulfur-coated urea (PCSCU) or an organic N source at 147 kg N ha-1 yr-1 produced no NO3-N leaching above MCL standards throughout a 36-mo residential lawn leaching study. Petrovic et. al. (1986) repor ted similar conclusions with anion exchange resin NO3-N detection techniques employed to a 30 cm depth under a Kentucky bluegrass lawn environment fertilized with PCU and Milorganite treatments at 98 kg N ha-1. Several studies have docume nted higher levels of NO3-N leaching from certain CRNS, which include sulfur-coated urea (SCU), IBDU, and methylene urea (Pet rovic et al., 1986; Snyder et al.
59 1981, 1984). In the present study, there was a tend ency for controlled-release liquid (CRL) treatments to leach higher concentrations of NOx-N compared to BSD or PCU, particularly at 147 kg N ha-1 (Table 3-3). Over each 30-d period after fertilization with the highest N rate of CRL (147 kg ha-1), peak NOx-N concentrations of 25.2, 63.5, and 32.4 mg NOx-N L-1 were detected in leachates shortly after fertilization during cycle 1, 3, and 4, respectively (Fig. 3-4, 35). According to manufacturer labeling, this N rate should deliver ~59 kg soluble N ha-1 perapplication and subsequently NOx-N leaching was consistent with initial losses recorded from urea N at 49 kg ha-1. However, the potential for urea to l each applied N, diminished under repeat fertilization. In contrast, 2.5-fold increases in NOx-N were observed from CRL in the subsequent cycle (Fig. 3-4, 3-5). This result could be expl ained by progressively lowe r turf density in CRL plots due to insufficient N release over the latter stages of each a pplication interval (Tables 2-4). The relationship between turf dens ity and the potential to leach NO3-N has not been well studied on established grass stands Research is required to addres s this concern, particularly in Florida where residential lawns may experience a de cline in turfgrass density due to inadequate PAN during the peak growing season under fertiliza tion restrictions, a fact or that may exacerbate NO3-N leaching through reduced N uptake under highe r soil infiltration rates (Petrovic, 1990). Current data indicates a clos e correlation betw een increasing turf coverage and reduced NO3-N leaching (Easton and Petrovic, 2008; Rosent hal and Hipp, 1993; Snyder and Cisar, 2000), however these studies have focused on turf establ ishment situations where low plant densities are cognately associated with immaturely rooted turf. Conversely, increased potential for NO3-N run-off losses due to low plant density has received attention and several studies have noted that run-off losses decline as turf density increases. These authors attributed lower nutrient run-off in dense turf due to the reduction in velocity as water travels a more tort uous path through densely
60 populated turf stands, thus resul ting in higher infiltra tion rates (Linde et al., 1995; Gross et al., 1990, 1991; Easton and Petrovic, 2004). However thes e studies were conducted largely on fine texture soils, with low infiltration rates, which is less of a concern in Florida due to the predominately sandy soil in populated coastal wate r-sheds. Erickson et al. (2001) showed that minimal inorganic N run-off was possible from a well fertilized, dense St Augustinegrass turf on a 10% slope due to intense precipitation. Ther efore, research focusing specifically on the relationship between St. Augustinegra ss density and how this impacts NO3-N run-off and leaching may be of importance in Florida. As shown, significant scientific data obtained over many year s document that certain CRNS at higher-application rates offer negligible c ontributions to ground-wa ter degradation. Our findings on a field-based St. Augustinegrass lawn system in Florida are consistent with previous studies and clearly demonstrate that both PCU and BSD can be applied at the N rates employed in this study (i.e. up to 147 kg ha-1) without significant risk from N species pollution of important ecological water resources or drinking water supp lies in Florida. Therefore we encourage local and state legislative bodies to consider revising their policies to permit higher-application N rates of BSD and PCU to allow judi cious fertilization throughout th e restrictive season to curve potentially negative impacts of St. Augustineg rass managed under insufficient PAN. (i.e. reduced turf density and RLD). Nitrogen Leaching Influenced by N Source Nitrogen loads were influenced by N sources at each application rate, although N rate brackets (i.e. 49 and 98 kg N ha-1) that utilized quick-release N, in itially offered the highest total N loads of this study. During cycle 1, urea at 49 kg N ha-1 leached 6.5 % of applied N and UPCU2 at 98 kg N ha-1, 12 % of applied N (Tables 3-4, 3-15 ). For urea, an additional 7% of applied N was leached in cycle 2 (Table 3-5) but thereafter maximum N losses were 2.3%
61 (Table 3-9) with the majority of cycle means showing N losses < 1% of applied N (Tables 3-6 3-8, 3-11 3-13). Nitrogen leaching from sources applied at N rates of 98 kg ha-1 were analogous to that observed under lower N strategi es, whereby initial high N load ing from UPCU2, were followed by losses 1.3% of applied N, although during the WS in 2008 losses of 3.6% of applied N were noted (Table 3-17). As mentioned above, N leached from BSD and PCU at the elevated N rate over extended re-application intervals produced th e lowest N leaching with average values of 0.9% of applied N leached over th e study period. To put this into context, total N losses from BSD and PCU at 147 kg N ha-1 were lower than the N inputs from the city irrigation water supply (Tables 3-20 3-22). Increased incidences of NOx-N in CRL leachates that were in excess of MCL standards were reported, which resulted in higher N leaching values as the study progressed. However, steady increases of 3.3, 4.0, and 4.2 kg ha-1 of total N leached represented only 2.2, 2.7, and 2.9 % of applied N leached in cycle 1, 3, and 4 respectively. Relative Recovery of Inorganic Nitrogen in Percolate and Clipping Evidently, low levels of N leaching resulted fr om fertilizer N strategies employed in this study. However, equally low levels of relative N r ecovery were also appare nt, particularly during the cooler DS. For example, when averaged ac ross each cycle, maximum relative N recovery from PCU3 and PCU2 were 56.4, and 51.7% of N inputs during the WS of 2008, respectively and only 3.6 and 3.9% of N was recovered durin g the DS from these sources. This clearly represents a large proportion of N unaccounted for. In his review, Petrovic (1990) reported that five major categories of the N cycle explain the fate of N applied to tu rfgrass: plant uptake, atmospheric loss, soil storage, leaching, and run-off. Plant uptake was quantified in the form of N recovered in clippings, however, temperature and season have been shown to influence N recove red in clippings and may explain considerably
62 lower relative N recovery under DS conditions. Many studies indica te that the majority of N applied to turf is recovered in clipping s (Hummel and Waddington, 1981; Starr and Deroo, 1981), but most studies were c onducted under near opt imum conditions for plant growth. South Florida is unique in that respect since growth persists year r ound for warm-season grass albeit with significant reductions dur ing the DS. Few studies have focused on N recovery from turf under sub-optimal temperatures. Mosdell and Schmidt (1985) examined N recoveries under temperatures deemed below optimum from Kentucky bluegrass under growth chamber conditions. They reported N recovery was 39% lower than comparative recoveries under favorable temperatures for growt h. Other studies that have examin ed N leaching and visually turf responses in temperate climate reported insuffici ent growth to quantify tissue N concentrations from October to April (Mangiafico and Guilla rd, 2006; Weyner and Haley, 1993). In addition, since visual symptoms of fertilizer response we re observed during these below optimum periods, N uptake may have been allocate d to other plant parts (roots, crowns, stems, and stolons). Petrovic (1990) reported that 31 and 20 % of a pplied N could be apportioned in crowns and roots, respectively. Hummel and Waddington (1984) could only account for 1.5% of applied N in roots of Kentucky bluegrass. While, Varshovi (1995) observed that N recovery in roots and stolons of bermudagrass varied between 5 a nd 11% of applied N depending on N source. Potential Nitrogen Losses other than Leaching or Plant Uptake In this study, the portion of N in unmown pa rts of the plant may have been small and N run-off may be of little consequence due to th e topography and soil texture. Thus atmospheric loss and/or soil storage may have been the majo r sinks for applied N. Atmospheric loss of applied fertilizer N can occu r either through ammonia (NH3) volatilization or as denitrification (Petrovic, 1990). Ammonia volatilization from surface applied NH4-based fertilizers is influenced by soil pH, soil moisture, temperat ure, relative humidity (R H), fertilizer source,
63 cation exchange capacity (CEC), and depth of incorporat ion (Nelson, 1982). Reports of the magnitude of NH3 losses from surface applied urea on turf are inconsistent and range from 10% (Torello et al., 1983) to 68% of applied N (Fenn and Kissel, 1974). The majority of fertilizers in this experiment (9 of 12) were urea based, volat ile N loss may have been substantial given that environmental factors (i.e. high temperature and RH) were particularly favorable for volatilization during the WS. Irrigation was supplie d post-application in efforts to limit NH3 losses, but the rate (0.6 cm) may have been insufficient. Titko et al. (198 7) and Bouwmeester et al. (1985) reported that irrigati on rates of 2.5 and 2.4 cm respectiv ely were required to eliminate potential volatile losses from surface applied urea. Soil conditions were also conducive of volatil e N loss (Table 2-1). Torello et al. (1983) reported NH3 loss under acidic soil conditions (pH 6.4) was negligible. Conversely, under alkaline soils NH3 losses can be severe. Resear ch shows that appreciable NH3 is formed at a soil pH > 7.5 (Vlek and Craswell, 1981; Titko et al., 1987). Even with m ildly alkaline soil pH (7.1) in this study, palpable NH3 volatilization may have occurred (T able 2-1), since sharp increases in soil pH due to urea hydrolysis are expected for s hort intervals following urea application (Kissel et al., 2008). Guertal et al. (2007) reported that N source influenced NH3 volatilization on warm-season grass. The extent of gaseous N flux from their treatments were urea > methylene urea > sewage sludge > PCU. These findings may explain our highest N recovery with PCU (98 and 147 kg N ha-1); however, it fails to account for lower N recovery from CRL (12% Urea; 18% methylene urea and triazone) relativ e to urea at 49 kg ha-1. Clapp and Parham (1991) also found lower NH3 losses from a methlyene urea and triazone fert ilizer compared to ur ea, although, application method and soil factors may have influen ced gaseous losses in our experiment.
64 Firstly, in the present study CRL was the only source to be applied in liquid form and researchers have shown greater NH3 losses from dissolved versus granularly applied urea (Torello, 1983; Titko, 1987). Secondly, in creased organic matter (OM) reduces NH3 loss through the contribution of OM to CEC, which influences the retention of NH4. Soil analysis revealed significantly lower OM and CEC in CRL1 plots compared to urea (Table 2-1). Increased NH3 volatilization may explain progressively lower N recovery, yi eld and density from CRL (Tables 2-4, 2-5, 3-1, 3-8, 3-9, 3-12), particularly since slower accumulations of OM were observed in CRL plots compared to urea. NH3 loss may help to explain low N recovery during the WS, because N losses of 40% are not unusual in trop ical climates when conditions are favorable (Francis et al., 2008). However, environmental f actors such as high temperature and RH that could enhance the magnitude of NH3 losses in the WS were considerably lower during the DS (Appendix A), when N recoveries were consiste ntly lowest (Tables 3-7, 3-8, 3-12 3-14, 3-16, 319, 3-22), therefore, other factors may have contributed. Denitrification is a multi-step respiratory pathway by which facult ative anaerobes reduce NO3 to molecular N in anaerobic soil with organic or inorga nic electron donors and N oxide electron acceptors (Coyne, 2008). Sa nd soils are generally not associated with substantial N losses through denitrification, how ever, the soil profile within the lysimeter (i.e. constructed system with distinct textural layers, designed to prevent sand particulate migration and reduce percolate impediment) may have facilitated anaerobic conditions during the DS when percolate flow is notably reduced (Appendix B). For ex ample, Brown and Duble (1975) demonstrated having coarse textured strata within the soil pr ofile created a perched water table and increased the water retention of the entire profile. In essence, a saturate d zone would persist between the gravel and the sand in the lysimeter system and during periods of infrequent precipitation the
65 replenishment of oxygenated water may be limite d and anaerobic conditions may develop. Since organic electron donors would be available from seasonal regeneration and decomposition of root structures, conditions may be conducive for biological denitrificatio n during the DS. Under soil temperatures consistent with the season (20.9 25.5oC), denitrification losses ranging from 0.2 0.9 kg N ha-1 d-1 have been reported (Lensi and Chalamet, 1982; Groffman et al., 1991). Soil storage (immobilization), essentially the opposite of mineralization, in that immobilization is the conversion of inorganic N (NO3-N and NH4-N) to organic forms. On average OM content of the upper 10 cm soil la yer increased by ~1.5% over the 24-mo study period. The level in which fertilizer N is incorporated into OM is largely a function of turf stand maturity and during the period of increasing soil OM some of the fertilizer will be immobilized (Petrovic, 1990). Few studies have investigated the amount of fertilizer N that is eventually incorporated into OM under tu rf conditions and the author co uld not find published literature documenting this process in warm-season grass turf. Starr and Deroo (1981) evaluated the fate of N on cool-season grasses using labeled 15N and found that 15 21% of applied N was stored in the organic content of a sandy loam soil, 4-mo after the last applica tion. Watson (1987) reported similar conclusions ~2-mo after last fertilizer applications to pere nnial ryegrass grown on a sandy loam soil and noted that 13 17% of fertili zer N from urea was stored in the organic soil component. These findings suggest that soil storage or immobilization of fe rtilizer N in coastal soils in Florida may be significant, especially in immatu re residential landscapes which have been shown to accumulate N rapidly in the first 10-yr period. More research is warranted to determine the influence of St. Augustinegrass lawn maturity on the fertilization requirements based on the capacity of a soil to accumulate fertilizer N in the soil organi c-N pool. Long-term evaluations
66 may show that reduced inorganic-N inputs ar e needed as the soil OM content reaches equilibrium and remains relatively constant, thus re moving a potential fertilizer N sink. Conclusion This experiment has shown that various N strategies can be employed under St. Augustinegrass lawn conditions without serious implications to inorganic-N groundwater degradation. Based on these findings, N leaching from established residential St. Augustinegrass landscapes is expected to provide minor cont ributions to the pool of non-point source N pollutants in coastal watershed systems. Furthermor e, we find little benefit in N rate regulation in addition to that set forth by state legislative bodi es. In fact, restrictive fertilization seasons may have a detrimental environmental impact. For example, CRL at 147 kg N ha-1 that was allocated an N-release duration (180-d) far in excess of recommended re-application window (60 to 90-d) demonstrated severe symptoms of N deprivat ion (i.e. reduced turf density and quality). Incidences of NOx-N leaching in excess of MCL standard s were exacerbated progressively as these visual assessments deteriorated. These fi ndings may provide valuable information of the potential ramifications of rest rictive season legislation. If counties and municipalities are insistent on such fertilization bound aries, new revisions are require d to enable certain CRNS to be applied at higher pre-applications N rates th an currently permitted, pr ior to 120-d restrictive periods in order to sustain St. Augustinegrass density and root growth. For instance, PCU and BSD demonstrated the lowest inorganic-N leaching at N rates of 147 kg ha-1, and were capable of sustaining acceptable St. Augustinegrass visual assessments for 120-d durations. However, only low levels of applied N could be recovered in St. Augustinegrass clippings and inorganic-N leachates. We proposed three pot ential factors that may explain unaccounted for the majority of N not accounted for; (i) NH3 volatilization, (ii) denitr ification, and (iii) soil storage. Ammonia volatilization may be more prevalent under WS conditions and may have
67 induced losses of ~40% or more of applied N depending on the N source. Hydrological factors may have been most favorable during the DS due to lysimeter specifications and N losses may have been substantial. Due to turf stand immaturity and low soil OM levels, soil storage or immobilization of applied fertil izer N may have been in the magnitude of ~15%, although this value is based on temperate resear ch conditions. The relatively low le vels of N recovered in this study suggest that inorganic-N leach ing is not a major N flux in re sidential landscapes fertilized with these N sources but gaseous N loses may be more prevalent. Much more research is required in Florida to better understand the fate of applied N to a St. Augustinegrass under varying degrees of lawn maturity.
68 Table 3-1. The influence of N source applied at 49 kg N ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 60-d cycle across 2007 and 2008. TREATMENT ------------2007 -------------------------------2008 ---------------------Wet Season --Dry Season --Wet season ----Dry Season --C1 C2 C3 C5 C6 C7 C8 C9 C10 C11 C12 ------------------------------------------------------mg [NOx-N] L-1------------------------------------------------------BSD1 0.62 0.44 0.47 0.40 0.39 0.75 0.59 0.46 0.40 0.30 0.33 PCU1 0.64 0.43 0.43 0.41 0.30 0.48 0.59 0.44 0.38 0.29 0.31 CRL1 0.54 0.73 0.43 0.76 0.45 0.47 1.51 0.50 0.42 0.32 0.45 UPCU1 0.62 1.81 0.41 0.40 0.40 0.51 0.62 0.50 0.43 0.32 0.39 UREA1 6.40 3.09 0.38 0.41 0.32 2.32 0.59 0.50 0.34 0.25 0.95 CONTRAST UREA1 vs. OTHERS *** NS NS NS NS NS NS NS NS NS UREA vs. UPCU1 NS NS NS NS NS NS NS NS NS NS PCU1 vs. BS1 NS NS NS NS NS NS NS NS NS NS NS CRL1 vs. BS1 & PCU1 NS NS NS ** NS NS NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PCU = Polymer-coat ed urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 60-d cycle. The numeric demarcation that follows each treatment code indicates N rate and application frequency with 1 representing 49 kg ha-1 applied every 60-d. Single degree contrasts performed at the alpha level 0.05.
69 Table 3-2. The influence of N source applied at 98 kg N ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 120-d cycle across 2007 and 2008. TREATMENT ------2007 ------------2008 ------C1 C2 C3 C4 C5 C6 ---------------mg [NOx-N] L-1---------------BSD2 0.55 0.43 0.39 0.50 0.41 0.34 PCU2 0.53 0.55 0.35 0.48 0.43 0.26 CRL2 1.03 0.43 1.29 1.21 0.49 0.47 UPCU2 10.49 0.40 1.75 0.52 0.36 0.36 CONTRAST UPCU2 vs. OTHERS ** NS NS NS NS NS CRL2 vs. BSD2 & PCU2 NS NS NS NS NS NS BSD2 vs. PCU2 NS NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 120-d cycle. Single degree contrasts performed at the alpha level 0.05. Sample period (09/01/07 to 01/03/08) is incomplete, flow-weighted concentrations averaged between 09/01/07 and 11/07/07due to missing data. Table 3-3. The influence of N source applied at 147 kg ha-1 on flow-weighted concentration of NO3-N (mg L-1) averaged over each 180-d cycle across 2007 and 2008. TREATMENT --2007 ----------2008 -------Wet Season Wet Season Dry Season C1 C3 C4 -----------mg [NOx-N] L-1-----------BSD3 0.48 0.47 0.52 PCU3 0.50 0.53 0.32 CRL3 1.20 2.85 2.43 CONTRAST CRL3 vs. BSD3 & PCU3 NS ** BSD3 vs. PCU3 NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Treatment code: CRL = Control release liquid; PC U = Polymer-coated urea; BSD = Activated sewage sludge biosolid; and UPCU = Urea in equal N combination with polymer-coated urea. C = Means of 3 replications, averaged over each 180-d cycle. Single degree contrasts performed at the alpha level 0.05.
70 Fig. 3-1. NOx-N leached in cycle 1 (April 30-August 31, 2007) influenced by N sources applied every 120-d at 98 kg N ha-1 and precipitation during the WS. Vertical dashed lines indicate urea fertilization every 60-d at 49 kg N ha-1. Precipitation values summed over each sampling period. Fig. 3-2. NOx-N leached in cycle 4 (May 10-Spetmeber 6, 2008), influenced by N sources applied every 120-d at 98 kg N ha-1 and precipitation during the WS. Vertical dashed lines indicate urea fertiliza tion every 60-d at 49 kg N ha-1, included for comparative interest. Precipitation values summed over each sampling period. 0 50 100 150 200 250 5/1/20075/15/20075/29/20076/12/20076/26/20077/10/20077/24/2007 8/7/2007 8/21/2007SAMPLING DATESPERCOLATE NOx-N (mg l-1)0 20 40 60 80 100 120 140PRECIPITATION (mm ) BSD2 CRL2 PCU2 UPCU2 UREA1 PRECIPITATION 0 10 20 30 40 50 60 70 5/16/20085/30/20086/13/20086/27/20087/11/20087/25/20088/8/20088/22/20089/5/2008 SAMPLING DATESPERCOLATE NOx-N (mg L-1)0 10 20 30 40 50 60 70 80 90 100PRECIPITATION (m m BSD2 CRL2 PCU2 UPCU2 UREA1 PRECIPITATION
71 Fig. 3-3. NOx-N leached during cycles 1-3 (May 10Spetmeber 6), influenced by N sources applied every 60-d at 49 kg N ha-1 and precipitation during th e WS. Vertical dashed lines indicate fertilization dates. Preci pitation values summed over each sampling period. Fig. 3-4. NOx-N leached in cycle 1 (April 30 November 7), influenced by N sources applied at 147 kg N ha-1 every 180-d and precipitation durin g the WS. Precipitation values summed over each sampling period. 0 10 20 30 40 50 60 70 80 90 5/1/075/15/075/29/076/12/076/26/077/10/077/24/078/7/078/21/079/4/079/18/0710/2/0710/16/0710/30/07SAMPLING DATESPERCOLATE NOx-N (mg l-10 20 40 60 80 100 120 140PRECIPITATION (mm) BSD1 CRL1 PCU1 UPCU1 UREA1 PRECIPITATION 0 5 10 15 20 25 30 5/1/20075/15/20075/29/20076/12/20076/26/20077/10/20077/24/20078/7/20078/21/20079/4/20079/18/200710/2/200710/16/200710/30/2007SAMPLING DATESPERCOLATE NOx-N (mg L-1)0 20 40 60 80 100 120 140PRECIPITATIN (m m BSD3 PCU3 CRL3 PRECIPITATION
72 Fig. 3-5. NOx-N leached during cycles 3 and 4 (M ay 10, 2008 May 15, 2009), influenced by N sources applied at 147 kg N ha-1 every 180-d and precipitation. Vertical dashed line indicates fertilization date Precipitation values summed over each sampling period. 0 10 20 30 40 50 60 70 5/16/20086/13/20087/11/20088/8/20089/5/200810/3/200810/31/200811/28/200812/26/20081/23/20092/20/20093/20/20094/17/2009SAMPLING DATESPERCOLATE NOx-N (mg L-1)0 20 40 60 80 100 120PRECIPITATION (m m BSD3 PCU3 CRL3 PRECIPITATION
73 Table 3-4. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 June 30, 2007). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC -------------------------kg ha-1 -----------------------------% ----BSD1 49 0.93 0.34 0.55 0.89 2.93 1.8 7.6 PCU1 49 0.93 0.35 0.57 0.93 1.16 1.9 4.2 CRL1 49 0.93 0.29 0.49 0.78 1.56 1.6 4.7 UPCU1 49 0.93 0.34 0.54 0.88 1.98 1.8 5.7 UREA1 49 0.93 2.75 0.49 3.25 3.41 6.5 13.3 CV (%) 23.4 17.1 21.7 40.4 26.2 CONTRAST UREA VS. OTHERS ** NS ** NS ** UREA VS. UPCU1 NS NS CRL1 VS. BSD1, PCU1 NS NS NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Source code: CRL1 = Control release liquid; PCU1 = Polymer-coated urea; BSD1 = Activated sewage sludge bio-solid; UPCU1 = Urea in equal N combina tion with polymer-coated urea; Urea1 = Urea. All sources applied at 49 kg N ha-1every 60-d. FERT: Fertilizer N applied per application cycle. IRRIG: N supplied via irrigation, concentrations determined weekly and multiplied by volume applied. TN: Total N summed from NOx-N and NH4-N leachates. NUP: N-uptake as a product of dry weight yield and tissue N content. NL: N leached, percent of applied. REC: Relative N recovery, the percent of inorganic-N recovered compared to N inputs.
74 Table 3-5. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 2 (July 1 August 31, 2007). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.62 0.23 0.31 0.54 12.6 1.1 26.5 PCU1 49 0.62 0.23 0.34 0.57 5.26 1.2 12.2 CRL1 49 0.62 0.40 0.39 0.79 4.25 1.6 9.7 UPCU1 49 0.62 0.99 0.31 1.30 10.96 2.6 24.7 UREA1 49 0.62 2.31 0.60 2.91 15.43 5.9 36.9 CV (%) 16.8 22.7 13.2 12.0 13.8 CONTRAST UREA VS. OTHERS ** ** ** NS UREA VS. UPCU1 NS ** NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-6. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 3 (September 1 November 7, 2007). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.43 0.25 0.24 0.49 5.50 1.0 12.1 PCU1 49 0.43 0.23 0.25 0.49 5.81 1.0 12.7 CRL1 49 0.43 0.24 0.22 0.46 1.15 0.9 3.3 UPCU1 49 0.43 0.22 0.22 0.44 7.93 0.9 16.9 UREA1 49 0.43 0.21 0.21 0.42 8.19 0.8 17.4 CV (%) 8.5 8.1 8.2 35.2 32.1 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
75 Table 3-7. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 5 (January 6 March 7, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.70 0.16 0.07 0.24 0.53 0.5 1.54 PCU1 49 0.70 0.17 0.08 0.24 1.04 0.5 2.57 CRL1 49 0.70 0.73 0.13 0.86 0.45 1.7 2.64 UPCU1 49 0.70 0.16 0.07 0.23 1.05 0.5 2.57 UREA1 49 0.70 0.17 0.07 0.24 1.21 0.5 2.91 CV (%) 41.0 21.1 31.4 18.1 25.5 CONTRAST UREA VS. OTHERS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS BSD1 VS. PCU1 NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-8. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 6 (March 8 May 9, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.22 0.017 0.016 0.033 1.29 0.1 2.70 PCU1 49 0.22 0.013 0.013 0.026 2.04 0.1 4.20 CRL1 49 0.22 0.019 0.022 0.041 0.25 0.1 0.60 UPCU1 49 0.22 0.017 0.015 0.031 2.52 0.1 5.18 UREA1 49 0.22 0.014 0.013 0.026 2.71 0.1 5.56 CV (%) 19.6 18.9 18.8 22.3 20.7 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS ** NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
76 Table 3-9. Nitrogen budget of inputs vs. N acc ounted for by N leaching and St. Augustinegrass N uptake for cycle 7 (May 9 July 7, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.47 0.35 0.14 0.49 9.95 1.0 21.1 PCU1 49 0.47 0.22 0.09 0.32 15.39 0.7 31.76 CRL1 49 0.47 0.22 0.10 0.31 1.03 0.6 2.71 UPCU1 49 0.47 0.23 0.99 0.33 14.14 0.7 29.25 UREA1 49 0.47 1.07 0.77 1.15 12.52 2.3 27.63 CV (%) 46.2 13.0 37.5 32.5 28.6 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS ** ** BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-10. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 8 (July 8 September 6, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 1.24 0.22 0.37 0.58 16.7 1.2 34.3 PCU1 49 1.24 0.22 0.35 0.58 20.1 1.2 41.2 CRL1 49 1.24 0.57 0.38 0.95 4.1 2.0 10.1 UPCU1 49 1.24 0.23 0.43 0.66 18.1 1.3 37.4 UREA1 49 1.24 0.22 0.38 0.60 15.8 1.2 32.7 CV (%) 22.4 12.1 26.2 21.1 34.0 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS ** BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
77 Table 3-11. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 9 (September 6 November 13, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.52 0.020 0.024 0.044 10.1 0.1 20.5 PCU1 49 0.52 0.019 0.027 0.046 10.9 0.1 22.1 CRL1 49 0.52 0.022 0.025 0.047 3.2 0.1 6.6 UPCU1 49 0.52 0.023 0.024 0.047 12.0 0.1 24.3 UREA1 49 0.52 0.022 0.025 0.047 12.1 0.1 24.5 CV (%) 10.9 20.5 21.7 23.2 23.2 CONTRAST UREA VS. OTHERS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS ** ** BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-12. Nitrogen budget of inputs vs. N account ed for by N leaching and St. Augustinegrass N uptake for cycle 10 (November 14 January 13, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.83 0.167 0.205 0.371 0.69 0.7 2.13 PCU1 49 0.83 0.152 0.200 0.352 0.77 0.7 2.51 CRL1 49 0.83 0.172 0.311 0.483 0.38 1.0 1.48 UPCU1 49 0.83 0.172 0.254 0.426 0.92 0.9 2.70 UREA1 49 0.83 0.134 0.260 0.395 1.20 0.8 3.21 CV (%) 15.5 26.9 20.4 13.3 21.3 CONTRAST UREA VS. OTHERS NS NS NS ** UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
78 Table 3-13. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 11 (January 14 March 12, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.13 0.106 0.497 0.603 0.290 1.2 1.82 PCU1 49 0.13 0.098 0.267 0.364 0.319 0.7 1.39 CRL1 49 0.13 0.107 0.529 0.637 0.192 1.3 1.68 UPCU1 49 0.13 0.113 0.451 0.564 0.355 1.1 1.87 UREA1 49 0.13 0.081 0.301 0.382 0.367 0.8 1.53 CV (%) 22.9 20.6 17.8 11.7 12.2 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU1 NS NS NS NS NS CRL1 VS. BSD1, PCU1 NS NS NS NS BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-14. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 12 (March 13 May 15, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD1 49 0.21 0.111 0.137 0.249 2.60 0.5 5.8 PCU1 49 0.21 0.109 0.124 0.231 3.16 0.5 6.9 CRL1 49 0.21 0.167 0.365 0.532 0.65 1.1 2.4 UPCU1 49 0.21 0.135 0.141 0.277 2.98 0.6 6.6 UREA1 49 0.21 0.671 0.126 0.797 2.97 1.6 7.7 CV (%) 37.8 9.3 23.6 16.8 15.2 CONTRAST UREA VS. OTHERS ** NS NS UREA VS. UPCU1 NS NS NS CRL1 VS. BSD1, PCU1 NS *** *** ** BSD1 VS. PCU1 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
79 Table 3-15. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 August 31, 2007). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD2 98 1.55 0.60 0.94 1.54 10.0 1.5 11.6 PCU2 98 1.55 0.56 1.02 1.59 17.9 1.6 19.5 CRL2 98 1.55 1.11 0.95 2.05 7.5 2.1 9.6 UPCU2 98 1.55 11.10 0.87 11.97 16.1 12.0 28.2 UREA1 98 1.55 12.76 1.09 13.84 18.9 13.9 32.8 CV (%) 20.9 21.5 16.1 16.2 9.1 CONTRAST UREA VS. OTHERS ** NS ** NS *** UREA VS. UPCU2 ** NS ** NS *** CRL2 VS. BSD2, PCU2 NS NS NS BSD2 VS. PCU2 NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Source code: CRL2 = Control release liquid; PCU2 = Polymer-coated urea; BSD2 = Activated sewage sludge bio-solid; UPCU2 = Urea in equal N combina tion with polymer-coated urea; Urea1 = Urea. All sources applied at 98 kg N ha-1every 120-d, expect Urea1 applied at 49 kg N ha-1every 60-d FERT: Fertilizer N applied per application cycle. IRRIG: N supplied via irrigation, concentrations determined weekly and multiplied by volu me applied. TN: Total N summed from NOx-N and NH4-N leachates. NUP: N-uptake as a product of dry weight yield and tissue N content. NL: N leached, percent of applied. REC: Relative N recovery, th e percent of inorganic-N recovered compared to N inputs.
80 Table 3-16. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 3 (January 6 March 7, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD2 98 0.92 0.175 0.085 0.260 1.350 0.3 1.63 PCU2 98 0.92 0.176 0.086 0.449 2.983 0.5 4.19 CRL2 98 0.92 0.890 0.273 0.976 0.573 1.0 0.84 UPCU2 98 0.92 1.238 0.087 1.325 3.540 1.3 4.92 UREA1 98 0.92 0.183 0.088 0.271 3.910 0.3 4.22 CV (%) 19.2 19.9 28.5 24.2 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU2 NS NS CRL2 VS. BSD2, PCU2 ** NS BSD2 VS. PCU2 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-17. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 4 (May 16 September 6, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD2 98 1.7 0.424 0.413 0.837 19.1 0.8 20.0 PCU2 98 1.7 0.402 0.446 0.848 50.7 0.9 51.7 CRL2 98 1.7 1.018 0.642 1.661 3.5 1.7 5.2 UPCU2 98 1.7 3.185 0.370 3.555 27.5 3.6 31.2 UREA1 98 1.7 1.298 0.457 1.756 28.4 1.8 30.2 CV (%) 31.4 9.9 22.8 16.4 11.7 CONTRAST UREA VS. OTHERS NS NS NS NS NS UREA VS. UPCU2 NS NS NS NS CRL2 VS. BSD2, PCU2 NS NS *** *** BSD2 VS. PCU2 NS NS NS ** ** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
81 Table 3-18. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 5 (September 7 January 13, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD2 98 1.35 0.164 0.206 0.370 11.30 0.4 11.67 PCU2 98 1.35 0.151 0.201 0.349 10.64 0.4 10.96 CRL2 98 1.35 0.197 0.254 0.450 3.48 0.5 3.92 UPCU2 98 1.35 0.134 0.174 0.309 12.75 0.3 13.06 UREA1 98 1.35 0.157 0.286 0.442 13.30 0.4 13.74 CV (%) 21.1 24.9 22.8 14.9 14.1 CONTRAST UREA VS. OTHERS NS NS NS ** ** UREA VS. UPCU2 NS NS NS ** ** CRL2 VS. BSD2, PCU2 NS NS NS *** *** BSD2 VS. PCU2 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-19. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 6 (January 14 May 15, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD2 98 0.33 0.243 0.689 0.936 1.45 1.0 2.42 PCU2 98 0.33 0.191 0.873 0.587 3.26 0.6 3.91 CRL2 98 0.33 0.338 0.391 1.210 0.54 1.2 1.77 UPCU2 98 0.33 0.260 0.718 0.987 1.45 1.0 2.48 UREA1 98 0.33 0.753 0.426 1.174 3.35 1.2 4.59 CV (%) 29.9 15.2 19.0 21.8 20.6 CONTRAST UREA VS. OTHERS NS NS NS ** *** UREA VS. UPCU2 NS NS NS NS NS CRL2 VS. BSD2, PCU2 NS NS ** BSD2 VS. PCU2 NS NS NS ** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
82 Table 3-20. Nitrogen budget of inputs vs. N account ed for by N leaching and St. Augustinegrass N uptake for cycle 1 (April 30 November 7, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD3 147 1.98 0.79 1.10 1.89 20.87 1.3 15.27 PCU3 147 1.98 0.78 1.33 2.11 42.49 1.4 29.94 CRL3 147 1.98 1.98 1.32 3.30 11.63 2.2 10.02 UREA1 147 1.98 12.97 1.30 14.27 27.10 9.6 27.73 CV (%) 23.7 10.3 18.1 13.1 6.4 CONTRAST UREA VS. OTHERS ** NS NS ** CRL3 VS. BSD3, PCU3 NS NS NS ** *** BSD3 VS. PCU3 NS NS NS ** *** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Source code: CRL3 = Control release liquid; PCU3 = Polymer-coated urea; BSD3 = Activated sewage sludge bio-solid; Urea1 = Urea. All sources applied at 147 kg N ha-1every 180-d, expect Urea1 applied at 49 kg N ha-1every 60-d FERT: Fertilizer N applied per application cycle. IRRIG: N supplied via irrigation, concentrations determined weekly and multiplied by volume applied. TN: Total N summed from NOx-N and NH4-N leachates. NUP: N-uptake as a product of dry weight yield and tissue N content. NL: N leached. REC: Relative N recovery, the percent of inorganic-N recovered compared to N inputs.
83 Table 3-21. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 3 (May 10 November 13, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD3 147 2.23 0.403 0.363 0.765 45.62 0.5 31.09 PCU3 147 2.23 0.471 0.499 0.969 83.22 0.6 56.42 CRL3 147 2.23 3.173 0.834 4.006 4.92 2.7 5.98 UREA1 147 2.23 1.32 0.482 1.802 40.47 1.2 28.33 CV (%) 31.9 8.53 21.5 12.7 11.8 CONTRAST UREA VS. OTHERS NS NS NS NS NS CRL3 VS. BSD3, PCU3 NS *** NS *** *** BSD3 VS. PCU3 NS NS NS ** ** NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001 Table 3-22. Nitrogen budget of inputs vs. N acco unted for by N leaching and St. Augustinegrass N uptake for cycle 4 (November 13 May 15, 2008). SOURCE NITROGEN BUDGET N INPUTS INORGANIC-N RECOVERED FERT IRRIG NOx-N NH4-N TN NUP NL REC ------------------------kg ha-1 ----------------------------% ----BSD3 147 1.17 0.584 0.943 1.532 3.093 1.0 3.12 PCU3 147 1.17 0.363 0.655 1.016 4.353 0.7 3.62 CRL3 147 1.17 2.677 1.549 4.227 1.127 2.9 3.61 UREA1 147 1.17 0.888 0.687 1.569 4.543 1.1 4.13 CV (%) 14.5 11.9 7.7 10.3 8.5 CONTRAST UREA VS. OTHERS NS NS NS ** NS CRL3 VS. BSD3, PCU3 ** ** *** *** NS BSD3 VS. PCU3 NS NS NS NS NS NS, *, **, ***, = P>0.05, P<0.05, P<0.01, P<0.001
84 APPENDIX A CLIMATOLOGY DATA Table A-1. Clim atology data (May-April, 2007 and 2008) for Ft. Lauderdale (FLR EC), FL, with long term norms. SOIL TOTAL AIR TEMPERATURE TOTAL TEMPERATURE RELATIVE SOLAR 2007 2008 RAINFALL (10 cm) HUMIDITY RADIATION MONTH MAX. MIN. AVG. MAX. MIN. AVG. NORM. 2007 2008 2007 2008 200720082007 2008 -------------------------OC ----------------------------mm -------OC -------% -----W m-2 --MAY 33.5 15.0 25.0 35.1 16.5 26.6 25.8 109.2 100.6 26.0 27.7 70 71 242.7 276.8 JUNE 34.5 19.8 26.3 33.1 21.4 27.5 27.3 479.3 60.2 27.3 28.4 77 80 233.0 227.4 JULY 34.1 15.3 26.7 33.6 21.6 27.3 28.1 264.4 262.6 28.3 28.0 79 82 222.0 215.2 AUGUST 35.0 22.7 28.7 34.7 22.8 28.1 27.9 43.4 239.3 29.2 28.3 76 83 238.2 201.6 SEPTEMBER 34.9 22.1 27.6 32.4 21.9 27.8 27.2 287.0 160.3 28.3 28.0 80 82 193.0 188.9 OCTOBER 32.7 22.6 27.1 31.7 11.5 25.1 25.5 265.4 204.5 26.5 25.5 82 78 150.1 166.4 NOVEMBER 29.3 12.8 22.8 31.5 9.2 20.8 22.8 59.7 27.2 23.4 22.6 75 76 158.7 165.1 DECEMBER 29.5 10.3 22.8 28.6 9.7 20.8 20.1 17.3 10.7 23.0 21.2 81 80 145.6 129.5 JANUARY 29.2 3.3 20.2 29.3 4.6 18.6 19.6 41.7 2.8 21.1 20.7 77 76 141.4 153.7 FEBRUARY 31.9 8.7 22.3 30.3 2.2 19.1 19.2 126.5 6.9 22.4 21.2 77 70 169.4 187.4 MARCH 32.3 10.4 22.6 30.2 6.4 21.3 22.1 140.2 122.7 22.7 23.0 74 68 193.2 207.4 APRIL 32.2 12.7 23.6 32.0 10.6 23.9 23.6 84.8 28.4 25.1 26.0 71 66 259.5 252.3 MEAN 32.4 14.6 24.6 31.9 13.2 23.9 24.1 159.9 102.2 25.3 25.1 77 76 195.6 197.6 NORM = Average from 2003 to 2007.
85 APPENDIX B PERCOLATE VOLUMES 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 5/1/077/1/079/1/0711/1/071/1/083/1/085/1/087/1/089/1/0811/1/081/1/093/1/095/1/09 SAMPLING DATESPERCOLATE VOLUME (l m-2) Fig. B-1. Percolate volumes averaged across ea ch treatment collected over the 24-mo study period, indicating generally lower percolat e during the DS (November 1 May 1), although sporadic significant precipitati on induced percolation was evident.
86 LIST OF REFERENCES Ballar, C.L., R.A. Sanc hez, L.A. Scopel, J.J. Casal, and C.M. Ghersa. 1987. Early detection of neighbouring plants by phytochrome perception of spectral cha nges in reflected sunlight. Plant Cell and Environ. 10:551-557. Barton, L., G.G.Y. Wan, and T.D. Colmer. 2006. Turfgrass (cynodon dactylon L.) sod production on sandy soils: II. Effects of irri gation and fertilizer regimes on N leaching. Plant and Soil. 284:147-164. Barbarick, K.A., J.A. Ippolito, and D.G. Westfa ll. 1997. Sewage biosolids cumulative effect on extractable-soil and grain elemental conc entrations. J. Environ. Qual. 26:1696-1702. Barbarick, K.A. and J.A. Ippolito. 2007. Nutrient assessment of a dryland wheat agroecosystem after 12 years of biosolid a pplication. Agron. J. 99:715-722. Bowman, D.C., D.A. Dewitt, M.C. Engelke, a nd T.W. Rufty, Jr. 1998. Root architecture affects nitrate leaching from bentgr ass turf. Crop Sci. 38:1633-1639. Bowman, D.C. Bowman, C.T. Cherney, and T.W. Rufty, Jr. 2002. Fate and Transport of nitrogen applied to six warm-season turf grasses. Crop Sci. 42:833-841. Bouwmeester, R.J.B., P.L.G. Vlek, and J.M. Stumpe. 1985. Effect of en vironmental factors on ammonia volatilization from a urea-fertilized soil. Soil Sci. Soc. Am. J. 49:376-381. Box, G.E.P. and D.R. Cox. 1964. An analysis of Tr ansformations. J. Royal Stat. Soc. Series B (Methodological). 26(No.2):211-252. Brown, K.W., R.L. Duble, and J.C. Thomas. 1977. Influence of management and season on fate of N applied on golf greens. Agron. J. 69:667-671. Brown, K.W., and R.L. Duble. 1975. Physical characteristics of so il mixtures used in golf green construction. Agon. J. 67:647-652. Carrow, R.N, B.J. Johnson, and R.E. Burns. 1987. Thatch and quality of tifway bermudagrass turf in relation to fertility and cultivation. Agron. J. 79:524-530. Carrow, R.N. and B. J. Johnson. 1989. Frequency of Fertilizer Applications and Centipedegrass Performance. Agron. J. 1988 80: 925-929. Carrow, R.N. 1997. Turfgrass response to slow-rele ase nitrogen fertilizers. Agron. J. 89:491-496. Casal, J.J., R.A. Sanchez, and V.A. Deregibus. 1986. Variation in tiller dynamics and morphology in lolium multiflorum Lam. Vegetati ve and reproductive plants as affected by differences in red/far-red irradi ance. Environ. Exp. Botany. 26:365-371.
87 Casal, J.J., R.A. Sanchez, and D. Gibson. 1990. Th e significance of change s in the red/far-red ratio, associated with either neighbour ing plants at twi light, for tiller in Lolium multiflorum Lam. New Phytol. 116:565-572. Chinualt, S.L. and G.A. OConnor. 2008. Phosphor ous release from bio-solids-amended sandy spodosol. J. Environ. Qual. 37:937-943. Christianson, C.B. 1988. Factors affecting N release of urea from reactive layer coated urea. Fert. Res. 16:273-284. Cisar, J.L., G.H. Snyder, J.L. Haydu, and K.E. Williams. 2001. Turf response to coated-urea fertilizer. II. Nitrogen content in clippings, nitrogen uptake, and nitrogen retention from prills. Int. Turfgrass Res. J. 9:368-374. Clapp, J. G. Jr. 2001. Urea-triazone N characteristics and uses. In: Optimizing Nitrogen Management in Food and Energy Production and Environmental Protection: Proceedings of the 2nd International Nitrogen Conference on Science and Policy. TheScientificWorld (2001) 1:103-107. Clapp, J. G. Jr. and T. M. Parham Jr. 1991. Properties and uses of liquid urea-triazone-based nitrogen fertilizers. Fert. Res. 28:229-232. Clewer, A.G. and D.H. Scarisbrick. 2001. Practical Statistics and Experimental Design for Plant and Crop Science. J. Wiley & Sons Inc. N.Y. Conrad, J.P. 1942. Enzymatic vs. microbial conc epts of urea hydrolysis in soils. Agron. J. 34:1102-1113. Council of the City of Sannibel. 2006. Agenda item #4[b] http://sanibelh2omatters.com/fertilizer/PDF/New s/Fertilizer_ connection_to_red_tide.pdf. Council of the City of Sannibel. 2007. Ordinance No. 07-003. http://www.sanibelh2omatters.com/fert ilizer/PDF/Fertilizer_Ordinance.pdf. County of Charlotte. 200 8. Ordinance No. 2008-028. http://charlotte.ifas.ufl.edu/horticulture/fertilizer/brochure.pdf. County of Lee. 2008. Ordinance No. 08-08. http://lee.ifas.ufl.edu/Hort/BrownsPla ntFiles/FertilizerOrdinanceFinal.pdf County of Sarasota. 2007. Fertilizer and landscape manageme nt code, Ordinance No. 2007-63. http://www.sarasota.wateratlas.usf.edu/upl oad/docum ents/Sarasota%20County%20Fertiliz er%20brochure.pdf. County of St. Jonhs. 2000. Ordinance No. 2000-60. http://www.clk.co.st-johns.fl.us/min rec/OrdinanceBooks/2000/ORD2000 -60.pdf.
88 County of St. Jonhs. 2000. Ordinance No. 2003-52. http://www.clk.co.st-johns.fl.us/minrec/ OrdinanceB ooks/2003/ORD2003-48.pdf. Coyne, M.S. 2008. Biological denitrification. p. 201-253. In J.S. Schepers and W.R. Raun (ed.) Nitrogen in agricultural systems. Agr on. Monogr. 49. ASA, CSSA, and SSSA, Madison, WI. Department of Agricultural and Cons umer services, No. 4640400, Rule 5E-1.003. 2007. http://www.dep.state.fl. us/water/nonpoint/. DiPaola, J.M., J.B. Beard, and H. Brawand. 1982. Key events in the seasonal root growth of bermudagrass and st. augustinegra ss. HortScience. 17(5):829-831. Easton, Z.M. and Petrovic, A.M. 2004. Fertiliz er source effect on ground and surface water quality in drainage from turfgr ass. J. Environ. Qual. 33:645-655. Engelsjord, M.E. and B.R. Singh. 1997. Effects of slow-release fertilizers on growth and on uptake and leaching of nutrients in Kentuc ky bluegrass turfs established on sand-based root zones. Can. J. Pant Sci. 77:433-444. Ericksen, A.B., and M. Kjeldby. 1987. A comparative study of urea hydrolysis rate and ammonia volatilization from urea and urea calciu m nitrate. Fert. Res. 11:9-24. Erickson, J.E., J.L. Cisar, J.C. Volin, G. H. Snyder. 2001. Comparing nitrogen runoff and leaching between newly established St. Augus tinegrass turf and alte rnative residential landscape. Crop Sci. 41:1889-1895. Erickson, J.E., J.L. Cisar, G.H. Snyder, D.M. Park, and K.E. Williams. 2005. Does a mixedspecies landscape reduce inorganic-nitrogen leaching compared to a conventional St. Augustinegrass lawn. Crop Sci. 48:1586-1594. Fenn, L.B., and D.E. Kissel. 1974. Ammonia volitization from surface applic ations of ammonia compounds on calcareous soil: E ffects of temperature and ra te of ammonia nitrogen application. Soil Sci. So c. Am. Proc. 38:606-610. Flipse, J.R., Jr., B.G. Katz, J.B. Lindner, and R. Markel. 1984. Sources of nitrate in groundwater in a sewer housing development, centra l Long Island, New York. Groundwater 32:418426. Florida Department of Environmental Prot ection. 2008. Florida green industries best management practices for protection of wa ter resources in Florida. Florida Dep. Environmental Protection. http://www.dep.s tate.fl.us/water/nonpoint/pubs.htm. Francis, D.D., M.F. Vigil, and A.R. Mosier. 2008. Gaseous Losses of Nitrogen other than through Denitrification. p. 255-279. In J.S. Schepers and W.R. Raun (ed.) Nitrogen in agricultural systems. Agron. Monogr. 49, ASA, CSSA, and SSSA, Madison, WI.
89 Frank, A.B. and L. Hofman. 1989. Light quality and stem numbers in cool-season forage grasses. Crop Sci. 34:468-473. Fraser, P., C. Chilvers, V. Beral, and M. J. H ill. 1980. Nitrate and human cancer: a review of the evidence. Intern. J. Epidemiology. 9:3-11 Fry, J.D., D.O. Fuller, and F.P. Maier. 1993. Nitrog en release from coated urea applied to turf. Int. Turfgrass Res. J. 7:533-539. Galloway, J.N. and E.B. Cowling. 2002. Reactive n itrogen and the world: 200 years of change. Ambio. 31:64-71. Galloway, J.N., F.J. Dentener D.G. Capone, E.W. Boyer, R.W. Howarth S.P. Seitzinger G.P. Asner, C. Cleveland, P. Green E. Holland, D. M. Karl, A.F. Michaels, J.H. Porters, A. Townsend and C. Vorsmarty. 2004. Nitrogen cy cles: past and future. Biogeochemistry. 70:153-226. Georgia Pacific. 2007. Plant Nutrition, Nitamin Brand Nitrogen Fertilizers. http://www.gp.com/PlantNutrition/product. Geron, C.A., T.K. Danneberger, S.J. Traina, T. J. Logan, and J.R. Street. 1993. The effects of establishm ent methods and fertilization practi ces on nitrate leaching from turfgrass. J. Environ. Qual. 19:663-668. Goertz, H.M. 1991. Commercial granul ar controlled release fertiliz ers for the speciality markets. p.51-67. In : R.M. Scheib (ed.) Proc. of Controlle d Release Fertilizer Workshop. Tennessee Valley Authority. Muscle Shoals, AL. Groffmann, P.M., E.A. Axelrod, J.L. Lemunyon, and W.M. Sullivan. 1991. Dentrification in grass and forest vegetation filter strips. J. Environ. Qual. 20:671-674. Gross, C.M., J.S. Angle, R.L. Hill, and M.S. Welterlen. 1991. Run-off and sediment losses from tall fescue under simulated rainfall. J. Environ. Qual. 20:604-607. Gross, C.M., J.S. Angle, and M.S. Welterlen. 1990. Nutrient and sediment losses from turfgrass. J. Environ. Qual. 19:663-668. Guillard, K. and K.L. Kopp. 2004. Nitrogen fertilizer form and associated nitrate leaching from cool-season lawn turf. J. Environ. Qual. 33:1822-1827. Guillard, K., and S.S. Mangiafico. 2006. Fall fertil ization timing effects on nitrate leaching and turfgrass color and growth. J. Environ. Qual. 35:163-171. Guertal, E.A., E.C. Knight, and C.W. Wood. 2007. Mowing and nitrogen source effects on ammonia volatilization from tu rfgrass. Crop Sci. 47:1628-1634. Haydu, J.J. and J.L. Cisar. 1990. Structural change s in the Florida sod in dustry. J. Farm Magers. 54:55-61.
90 Harper, J.J., and Boatman, B. 1926. Studies on nitr ification of ammonium sulfate in soils. Agon. J. 18:876-887. He, Z. L., A.K. Alva, P. Yan, Y.C. Li, D.V. Calvert, P.J. Stoffella, D.J. Banks. 2000. Nitrogen mineralization and transformation from composts and biosolids during field incubation in a sandy soil. Soil Sci. 165(2):161-169. Hummel, N.W.Jr., and D.V. Wa ddington. 1984. Sulfur-coated urea for turfgrass fertilization. Soil Sci. Soc. Am. J. 48:191-195. Hummel, N.W. Jr. 1989. Resin-coat ed urea evaluations for turf grass fertilization. Agron. J. 81:290-294. Hummel, N.W.Jr. and D.V. Wa ddington 1981. Evaluation of slow -release nitrogen sources on baron Kentucky bluegrass. Soil Sci. Soc. Am. J. 45:966-970. Hurt, G.W., C.V. Noble, and R.W. Drew. 1995. Soil survey of Monroe county, keys area, Florida. U.S.D.A. National Cooperative Soil Survey, IFAS University of Florida. http://soildatamart.nrcs.usda.gov/ma nuscripts/FL687/0/Monroe-Keys.pdf Johnson, B.J., R.N. Carrow, and R.E. Burns. 1987. Bermudagrass turf response to mowing practices and fertiliz er. Agron. J. 79:677-680. Kennedy, V.H., A.P. Rowland, and J. Parringt on. 1994. Quality assurance for soil nutrient analysis. Commun. Soil Sci. Plant Anal. 25:1605-1627. Keeney, 1986. Sources of nitrate to ground wate r. Crit. Rev. Environ. Control. 16:257-304. King, F.W. King, and J.C. Balogh. 2008. Nutrient and pesticide transport in surface run-off from perennial grasses in the urban landscape. In J.B. Beard and M.P. Kenna (ed.) Water quality and quantity issues from turfgrasses in ur ban landscapes. Council Agric. Sci. Tech. (CAST), Ames, IA. Kissel, D.E., M.L. Cabrera, and S. Para masivam. 2008. Ammonium, ammonia, and urea reactions in soils. In J.S. Schepers and W.R. Raun (ed.) Nitrogen in agricultural systems. Agron. Monogr. 49. ASA, CSSA, and SSSA, Madison, WI. Knight, T.M, D. Forman, R. Pirastu, P. Comba, R. Iannarilli, P.L. Cocco, G. Angotzi, E. Ninu, and S. Schierano. 1990. Nitrate a nd nitrite exposure in Italia n populations with different gastric cancer rates. Int J Epideimol. 19:510-515. Krans, J.V., and Morris, K. 2007. Determining a pr ofile of protocols and standards used in the visual field assessment of turfgrassses: A su rvey of National Turfgrass Evaluation Program sponsored university scientists. Appl Turfgrass Sci. dol:10.1094/ATS-2007-1130-01TT. Landschoot, P.J., and D.V. Wadding ton. 1987. Response of turfgrass to various nitrogen sources. Soil Sci. Soc. Am. J. 51:225-230.
91 Lee, D.J., and C.H. Peacock. 2005. Evaluation of the effect of natural organic sources on nitrogen release and turf grass quality. Int. Turfgr ass Res. J. 10:956-961. van Leeuwen, J.A., D. Walter-Toews, T. Abernathy, B. Smit, and M. Shoukri. 1999. Associations between stomach cancer incide nce and drinking water contamination with atrazine and nitrate in On tario (Canada) agroecosystems, 1987-1991. Int J Epideimol. 28:836-840. Lensi, R. and A. Chalamet. 1982. Den itrification in water-logged soils: In situ temperaturedependent variations. Soil Biol. Biochem. 14:51-55. Linde, D.T., T.L. Watschke, A.R. Jarett. 1998. Surface run-off comparison between creeping bentgrass and perennial ryegrass turf J. Turfgrass Management. 2:11-33. Linde, D.T., T.L. Watschke, A.R. Jarett, and J. A. Borger. 1995. Surface run-off assessment from creeping bentgrass and perennial ry egrass turf. Agron. J. 87:176-182. Littell, R.C., W.W. Stroup, R. J. Freund. 2002. SAS for Linear Models, 4th Ed. Cary, NC: SAS Institute Inc. Mangiafico, S.S., and Guillard, K. Cool-season tu rfgrass color and growth calibrated to leaf nitrogen. Crop Sci. 2007 47: 1217-1224. Mansouri, A. Review: methaemoglobinaemia. Am J Med Sci. 289:200-209. Marschner, H. 2002. Mineral nu trition of higher plants. 2nd Ed. P. 514-515. Academic Press, London, UK. McCollum, S.H., O.E. Cruz, Sr, L.T. Stem, W. H. Witterstruck, R.D. Ford, and F.C. Watts. 1978. Soil survey of Palm Beach County area, Fl orida. U.S.D.A. National Cooperative Soil Survey, IFAS University of Florida. http://soildatamart.nrcs.u sda.gov/m anuscripts/FL611/ 0/Palm_Beach.pdf. McCollum, S.H., and O.E. Cruz, Sr. 1981. Soil survey of Martin County area, Florida. U.S.D.A. National Cooperative Soil Survey, IFAS University of Florida. http://soildatamart.nrcs. usda.gov/m anuscripts/FL085/0/martin.pdf Methall, B.J., R.J. Hull, and C.R. Skogley. 1983. Cultivar variation in Kentucky bluegrass: P and K nutritional factors. Agron. J. 75:767-772. Miltner, E.D., B.E. Branham, A.E. Paul, and P.E. Rieke. 1996. Leaching and Mass balance of 15N-labelled urea applied to a Kentucky bluegrass turf. Crop Sci. 36:1427-1433. Moberg, E.L., D.V. Waddington, and J.M. Duic h. 1970. Evaluation of slow-release nitrogen sources on Merion Kentucky bluegrass. Soil Sci. Soc. Am. Proc. 34:335-339.
92 Moore, K.J., K.J. Boote, and M.A. Sanderson. 2004. Physiology and development morphology. p. 179-216. In L.E. Moser et al., (ed.) Warm-season (C4) grasses. Agron. Monogr. 45, ASA, CSSA, and SSSA, Madison, WI. Morris, K. 2001. NTEP Newsline: A publication of the National Turfgrass Evaluation Program. January March. Vol. 4, Issue 1. http://www.ntep.org/newsletter/News03_01.pdf. Morton, T.G., A.J. Gold, and W .M. Sullivan. 1988. Influence of overwater ing and fertilization on nitrogen losses from home lawns. J. Environ. Qual. 17:124-130. Mosdell, D.K., and R.E. Schmidt. 1985. Temperatur e and irrigation influen ces on nitrate losses of Poa pratensis L. turf. p. 487-494. In F.L. Lemaire (ed.) Proc. 5th Int. Turfgrass Research Conf., Avignon, France. 1-5 July. INRA Paris, France. Mueller, B.A., Nielson S.S., Preston-Martin S., Holly E.A., Cordier S., Filoppini G., Peris-Bonet R. and Choi N.W. 2004 Household water source and the risk of childhood brain tumors: results of the SEARCH inte rnational brain tumor study. Int J Epideimol. 33:1216-1218. Munshaw, C.G., E.H. Ervin, C. Shang, S.D. Aske w, X. Zhang, and R.W. Lemus. 2006. Influence of late-season iron, nitrogen, seaweed extract on fall color retention a nd cold tolerance of four Bermudagrass Cultivars. Crop Sci. 46:273-283. Nelson, K.E., A.J. Turgeon, and J.R. Street. 1980. Thatch influence on mobility and transformation of nitrogen carriers a pplied to turf. Agron. J. 72: 487-492. Nelson, D.W. 1982. Gaseous losses of nitrogen other than through dentrification. p. 327-364. In F.J. Stevenson (ed.) Nitrogen in agricultu re soils. Agron. Monogr. 22, ASA, CSSA, and SSSA, Madison, WI. Oertli, J.J. 1980. Controlled-release fertilizers. Fert. Res. 1:103-123. Peacock, C.H., and J.M DiPaola. 1992. Bermud agrass response to reactive layer coated fertilizers. Agron. J. 84:946-950. Peierls, B., N. Caraco, M. Pace, and J.J. Co le. 1991. Human influence on river nitrogen. Nature 350:386-387. Pendleton, R.F., H.D. Dollar, L. Law, Jr., S.H. McCollum, and D.J. Beiz. 1984. Soil survey of Broward County, Florida Easter Part. U.S.D. A. National Cooperative Soil Survey, IFAS University of Florida. http://soildatamar t.nrcs.usda.gov/manuscripts/FL606/0/broward.pdf. Petrovic, A.M., N.W. Hummel, and M.J. Ca rroll. 1986. Nitrogen source effects on nitrate leaching from late fall nitrogen applied to turfgrass. p. 137. In Agronomy abstracts. ASA, Madison, WI. Petrovic, A.M. 1990. The fate of nitrogenous fertili zers applied to turfgrass. J. Environ. Qual. 19:1-4.
93 Readon, E.A. 1966. New reactants for the colormet ric determination of ammonia. Clin. Chim. Acta. 14:403-405. Rieke, P.E., and B.G. Ellis. 1974. Effects of ni trogen fertilization on nitrate movement under turfgrasses. In E.C. Roberts (ed.) Proc. 2nd Int. Turfgrass Res. Conf. ASA, Madison, WI. 19-21 June 1972. Blacksburg, V.A. Rosenthal, W.D., and B.W. Hi pp. 1993. Field and model estimate s of pesticide run-off from turfgrass. p. 208-213. In K.D. Racke and A.R. Leslie (ed.) Pesticides in urban environments: Fate and significance Am. Chem. Soc., Washington, DC. Sabey, B.R., W.V. Bartholomew, R. Shaw, a nd J. Pesek. 1956. Influence of temperature on nitrification in soils. Soil Sci. Soc. Am. J. 20:357-360 Sarasota County, Florida, Ordinance 2007-062 (August 27, 2007). Sarigumba, T.I., and J.G.A. Fiskell. 1976. Urea tr ansformation in two acid sandy soils. Soil Crop Sci. Florida Proc. 35:150-154. Sartain, J.B. 1985. Effect of acidity and N source on the growth and thatch accumulation of Tifgreen Bermudagrass and on soil nutri ent retention. Agron. J. 77:33-36. Sartain, J. B. 1992. Effects of Coron and N-Sure liquid sl ow release N sources on growth and quality of cool and warm-season turfgrass. Turfgrass Research in Florida: A Technical Report. IFAS University of Florida. p. 137-146. Sartain, J. B. 1999. St. Augustinegrass response to natural organic fert ilizers. Turfgrass Research in Florida: A Technical Report. IF AS University of Florida. p. 51-57. Sartain, J.B., W.L. Hall, R.C. Little, and E.W. Hopwood. 2004. Development of methodologies for characterization of slow -release fertilizers. Soil Crop Sci. Florida Proc. 63:72-75. Sartain, J.B. 2007. General recommendations for fer tilization of turfgrasse s on Florida soils. Fla. Coop. Ext. Publication #SL21. http://www.edis.ifas.ufl.edu/LH014. SAS Institute. 1999. SAS/STAT Users Guide. Version 8.02. SAS Institute, Cary, NC. Skogley, C.R., and J.W. King. 1968. Controlled releas e nitrogen fertilization of turfgrass. Agron. J. 60:61-64. Skogley, C.R. and C. D. Sawy er. 1992. Field Research. p. 609. In D.V. Waddington et al. (ed.) Turfgrass. Agronomy Monograph 32. AS A, CSSA, and SSSA, Madison, WI. Smith, H., J.J. Casal, and G.M. Jackson. 1990. Reflection signals a nd the perception by phytochrome of the proximity of neighbouri ng vegetation. Plant Cell and Environ. 13: 7378.
94 Snyder, G. H., E.O. Burt, and J.M. Davidson. 1981. Nitrogen leaching in bermudagrass turf: 2. Effect of nitrogen N source and rates. In Proc. 4th Int. Turfgrass Res. Conf.. (Ed. R. W. Sheard) pp. 313-324 (University of Guelph: Ontario.) 19-23 July. Snyder, G.H., B.J. Augustin, and J.M. Davidson. 1984. Moisture sensor-controlled irrigation for reducing N leaching in Bermudagrass turf. Agron. J. 76:964-969. Snyder, G.H., and J.L. Cisar. 2000. Monitoring vadose-zone soil water for reducing nitrogen leaching on golf courses. p. 243-254. In J.M. Clark and M.P. Kenna (ed.) Fate and management of turfgrass chemicals. Vol. 743. Am. Chem. Soc. Washington, D.C. Spangenberg, B.G., T. W. Fermanian, and D. J. Wehner. 1986. Evaluation of liquid-applied nitrogen fertilizers on Kentucky bluegr ass turf. Agron. J. 1986 78: 1002-1006. Stanford, G., J. N. Carter, D. T. Westerma nn, and J. J. Meisinger. Residual nitrate and mineralizable soil nitrogen in relation to nitrogen uptake by irrigated sugarbeets Agron. J. 1977 69: 303-308. Starr, J.L., and H.C. Deroo. 1981. The fate of nitrogen applied to turfgrass. Crop Sci. 21:531536. Subhrajit, K.S. and L.E. Trenholm. 2005. Eff ect of fertilizer source on water use of St. Augustinegrass and ornamental plants. HortSci 40(7):2164-2166. Titko, S., J.R. Street, and T.J. Logan. 1987. Vo latilization of ammonia from granular and dissolved urea applied to turf. Agron. J. 79:535-540. Torello, W.A., and D.J. Wehner. 1983. Urease activ ity in a Kentucky bluegrass turf. Agron. J. 75:654-656. Torello, W.A., D.J. Wehner, and A.J. Turge on. 1983. Ammonia volatiliza tion from fertilized turfgrass stands. Agron. J. 75:454-456. Townsend, T.R., R.W. Howarth, F.A. Bazzaz, M.S. Booth, C.C. Cleveland, S.K. Collinge, A.P. Dobson, P.R. Epstein, E.A. Holland, D.R. Keeney, M.A. Mallin, C.A. Rogers, P. Wayne, and A.H. Wolfe. 2003. Human health effects of a changing global nitrogen cycle. Front Ecol. Environ. 5:240-246. Trenholm, L.E. and J.B. Unruh. 2007. St. Augustinegrass fertilizer trials. J. Plant Nutrition, 30:453-461. Trenkel, M.E. 1997. Improved Fertilizer Use Effi ciency: Controlled release and stabilized fertilizers in agriculture. Intern. Fertilizer Assoc. Paris, France. Turner, T.R., and N.W. Hummel Jr. 1992. Nutritional Requirements and Fertilization. p. 387439. In D.V. Waddington et al. (ed.) Turfgras s. Agronomy Monograph 32. ASA, CSSA, and SSSA, Madison, WI.
95 U.S. Environmental Protection Agency. 1999. Document 40 CFR Part 503: Biosolids Management Handbook, U.S. EPA Region 8, se ction 3.5-7, table 3.5.4 (mineralization rates). http://www.epa.gov/region8/wate r/biosolids/pdf/handbook3.pdf US Census Bureau. 2008. Estim ates and ProjectionsStates. http://www.census.gov/compendi a/statab/tables/09s0012.pdf. Van Dolah, F. M., K.B. Lidie, E.A. Monroe, D. Bhattach arya, L. Ca mpbell, G.J. Doucette, and D. Kamykowski. 2009. The Florida red tide dinofla gellate Karenia brevis : New insights into cellular and molecular proce sses underlying bloom dynamics. Harmful Algae. 8(4):562572. Varshovi, A. 1995. Nitrogen uptake and leaching pot ential of polymer-coated N fertilizers in turfgrass environment. Dissertation presente d to the University of Florida Graduate School, Gainesville, Fl. Vitousek, P.M., J.D. Aber, R.W. Howarth, G.E. Likens, P.A. Matson, D.W. Schinder, W.H. Schlesinger, and D.G. Tilman. 1997. Human alte ration of the gobal nitr ogen cycle: Sources and consequences. Ecol. Appl. 7:737-750. Volk, G.M. and G.C. Horn. 1975. Response curves of various turfgrasse s to application of several controlled-release nitrogen sources. Agron. J. 67:201-204. Waddington, D.V., E.L. Moberg, J.M. Duich, and T.L. Watschke. 1976. Long-term evaluation of slow-release nitrogen sour ces on turfgrass. Soil Sci. Soc. Am. J. 40:593-597. Waddington, D.V., J.T. Troll, and D. Hawes. 1963. Effects of Various fertilizers on Turfgrass, Yield, Color, and Composition. Agron. J. 56:221-223. Weyner, D.J. and J.E. Haley. 1993. Effects of late fall fertilization on turfgrass as influenced by application timing. Int. Turfgrass Res. J. 7:580:586. Williams, K.E., R.H. Snyder, J.L. Cisar, G.H. Snyder, and J.J. Haydu. 1997. Turf response to coated-urea fertilizer. 1. Visual quality and cl ipping yields. Int. Turf grass Res. J. 8:553562. Wolf, B. 1982. A comprehensive system of leaf analysis and its use for diagnosing crop nutrient status. Commun. Soil Sci. Plant Anal. 13:1035-1059. Wolfe, A.H. and Patz J.A. 2002. Reactive nitr ogen and Human Health: Acute and Long term implications. Ambio. 31:120-125. Wolf, B. and G.H. Snyder. 2003. Sustainable Soils : The place of organic matter in sustainable soils and their productivity. P. 56. The Haworth Press Inc. Binghamton, N.Y. Ylek, P.L.G, and E.T. Craswell. 1979. Ammonia volatilization from flooded soils. Fert. Res. 2:227-245.
96 BIOGRAPHICAL SKETCH Neil G. M. Young is the son of Dr. Graham and Anne Young and was born and raised in Aberdeen, Scotland. Neil spent much of his youth on the golf links with his father, where he became interested in turfgrass and the envir onment. Neil worked on golf courses during school holidays from the age of 13 and pursued a career in turfgrass management the traditional way in Scotland, by conducting an apprentic eship in greenskeeping. Later, Neil received a Bachelor of Science degree in turfgrass science from the Univ ersity of Central Lancashire, England in May 2005. He chose to travel and work internationally in the turfgrass indus try for several years before deciding to attend graduate school. Neil joined the Soil and Wa ter Department at the University of Florida and began his gradua te studies investigating the environmental implications of turfgrass fertilization under the supe rvision of Dr. George H. Snyder in May 2007. He received his Master of Science degree fr om the University of Florida in the Fall of 2009.