Elemental Sulfur Effects on Nutrient Availability in Organic Soil Having Variable Calcium Carbonate

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Elemental Sulfur Effects on Nutrient Availability in Organic Soil Having Variable Calcium Carbonate
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english
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Kaler, Avjinder Singh
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University of Florida
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Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Agronomy
Committee Chair:
Mccray, James M
Committee Co-Chair:
Erickson, John E
Committee Members:
Schnell, Ronald Wayne
Wright, Alan Lee

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Subjects / Keywords:
agricultural -- agronomy -- area -- calcium -- carbonate -- eaa -- elemental -- everglades -- fertilizer -- mangement -- muck -- nutrient -- ph -- soil -- sugarcane -- sulfur
Agronomy -- Dissertations, Academic -- UF
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Agronomy thesis, M.S.
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theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

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Abstract:
Organic soil subsidence is lowering the soil depth above the underlying limestone bedrock in the Everglades Agricultural Area. Incorporation of Ca carbonate into the root zone of soil from the underlying limestone increases pH and reduces availability of phosphorus and micronutrients to crops. Elemental S has been recommended at a rate of 560 kg ha-1 at soil pH > 6.6 to reduce soil pH and therefore increase nutrient availability to crops. There is a need to determine the effectiveness of elemental S in conditions of high pH and high Ca carbonate levels. The objective of this study was to determine elemental S effects on nutrient availability and sugarcane yield on organic soil having variable Ca carbonate content. A factorial pot experiment of 4 elemental S rates (0, 90,224, and 448 kg ha-1) and 3 organic soil types varying in added Ca carbonate (0%, 12.5%, and 50% by volume) was established using a randomized complete block design with four replications. Sulfur application had limited effects on soil pH reduction and therefore failed to enhance nutrient availability. Sulfur application increased sulfate concentration in soils that could be at risk for export from the field. With increasing the Ca carbonate in soil, pH increased and nutrient availability decreased, except for Mn. The expected reason for increased manganese availability was increased soil moisture associated with reducing conditions due to changes in physical properties of the soil with increased levels of Ca carbonate. High soil pH resulted in Mn and P deficiencies in the plants, and soil pH and Mn were important factors that influenced sugarcane yield. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-parent:"";mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin-top:0in;mso-para-margin-right:0in;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0in;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:"Calibri","sans-serif";mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;}
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In the series University of Florida Digital Collections.
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Includes vita.
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Statement of Responsibility:
by Avjinder Singh Kaler.
Thesis:
Thesis (M.S.)--University of Florida, 2013.
Local:
Adviser: Mccray, James M.
Local:
Co-adviser: Erickson, John E.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2014-08-31

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1 ELEMENTAL SULFUR EFFECTS ON NUTRIENT AVAILABILITY IN ORGANIC SOIL HAVING VARIABLE CALCIUM CARBONATE By AVJINDER SINGH KALER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2013

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2 2013 Avjinder Singh Kaler

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3 To my Parents and Grandmother

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4 ACKNOWLEDGMENTS I would like to express my sincere appreciation to my major advisor Dr. James M. McCray for giving me the opportunity to study at the University of Florida and for his trust, endless support, and guidance throughout my graduate study. I would also like to express my appreciation to my major co advisor, Dr. John E. Erickson, for his teachings and guidance. I would also like to give a special thanks to Dr. Alan L. Wright for his guidance during the research period and review of my papers. I would also like to thank my committee member, Dr. Ron ald W. Schnell. I thank Dr. Shangning Ji, Dr. Yigang Luo, Viviana Nadal, Irina Ognevich, and Ernst Guillaume for their assistance and guidance during experiment and laboratory analysis. I would also like to thanks Dr. Rongzhong Ye, previous graduate studen soil, really helped me in my research. I would like to thank my friends, Jugpreet, Gurpreet, Maninder, Hardev, Monica, and Harman who brought a lot of humor and normalcy to everyday life. And lastly, but far fr om least, I would like to thank my grandmother Dalip Kaur and parents, Jaswinder Kaur and Nirmal Singh, and whole Kaler family. Their support has been unwavering, and it is a blessing to have such loving people in my life.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 ABSTRACT ................................ ................................ ................................ ..................... 9 CHAPTER 1 BACKGROUND ................................ ................................ ................................ ...... 11 2 LITERATURE REVIEW ................................ ................................ .......................... 15 History of Everglades Agricultural Area ................................ ................................ .. 15 Importance of Sulfur Application ................................ ................................ ............. 16 Elemental Sulfur Application in EAA ................................ ................................ ....... 17 Effects of Excessive Elemental Sulfur Application ................................ .................. 18 3 MATERIALS AND METHODS ................................ ................................ ................ 21 Site and Experiment Description ................................ ................................ ............. 21 Soil Sampling and Analysis ................................ ................................ ..................... 22 Soil Sampling ................................ ................................ ................................ ... 22 Soil pH ................................ ................................ ................................ .............. 23 Mehlich 3 Extraction ................................ ................................ ......................... 23 Modified Acetic Acid Extraction ................................ ................................ ........ 23 2 M KCL Extraction ................................ ................................ .......................... 24 Water Extraction ................................ ................................ ............................... 24 Plant Data Collection ................................ ................................ .............................. 24 Leaf Sampling ................................ ................................ ................................ .. 25 Nitric Acid Digestion ................................ ................................ ......................... 25 Total Kjeldahl Nitrogen Digestion ................................ ................................ ..... 25 Silicon Digestion ................................ ................................ ............................... 26 Harvest Data ................................ ................................ ................................ .... 26 Statistical Analysis ................................ ................................ ................................ .. 27 4 ELEMENTAL SULFUR EFFECTS ON SOIL pH AND NUTRIENT AVAILABILITY IN HISTOSOLS HAVING VARIABLE CALCIUM CARBONATE LEVELS ................................ ................................ ................................ .................. 28 Introduction ................................ ................................ ................................ ............. 28 Materials and Methods ................................ ................................ ............................ 30 Site Description ................................ ................................ ................................ 30

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6 Soil Sampling and Analysis ................................ ................................ .............. 31 Statistical Analysis ................................ ................................ ............................ 32 Results and Discussion ................................ ................................ ........................... 33 Soil pH ................................ ................................ ................................ .............. 33 Extractable Nitrogen ................................ ................................ ......................... 34 Extractable Sulfate ................................ ................................ ........................... 35 Extractable Phosphorus ................................ ................................ ................... 36 Extractable Calcium, Magnesium, and Potassium ................................ ........... 36 Extractable Manganese ................................ ................................ .................... 37 Extractable Iron, Zinc, and Copper ................................ ................................ ... 38 Extractable Silicon ................................ ................................ ............................ 39 Conclusions ................................ ................................ ................................ ............ 40 5 RESPONSE OF SUGARCANE YIELD AND PLANT NUTRIENT CONCENTRATIONS TO SULFUR AMENDED ORGANIC SOILS VARYING IN CALCIUM CARBONATE CONTENT ................................ ................................ ...... 51 Introduction ................................ ................................ ................................ ............. 51 Materials and Methods ................................ ................................ ............................ 53 Site Description ................................ ................................ ................................ 53 Plant Data Collection ................................ ................................ ........................ 54 Leaf Sampling ................................ ................................ ................................ .. 54 Nitric Acid Digestion ................................ ................................ ......................... 55 Total Kjeldahl Nitrogen (TKN) Digestion ................................ ........................... 55 Silicon Diges tion ................................ ................................ ............................... 55 Harvest Data ................................ ................................ ................................ .... 56 Statistical Analysis ................................ ................................ ............................ 56 Results and Discussion ................................ ................................ ........................... 57 Nitrogen ................................ ................................ ................................ ............ 57 Phosphorus ................................ ................................ ................................ ...... 58 Sulfur, C alcium, Potassium, and Magnesium ................................ ................... 58 Manganese ................................ ................................ ................................ ....... 59 Iron, Copper, and Zinc ................................ ................................ ...................... 59 Silicon ................................ ................................ ................................ ............... 60 Millable Stalks ................................ ................................ ................................ .. 60 Sugarcane Yield ................................ ................................ ............................... 60 Yield Predictor ................................ ................................ ................................ .. 60 Conclusions ................................ ................................ ................................ ............ 61 6 SUMMARY ................................ ................................ ................................ ............. 73 LIST OF REFERENCES ................................ ................................ ............................... 75 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 80

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7 LIST OF TABLES Table page 4 1 Soil pH and extractable macronutrients for the 0 15 cm depth. .......................... 41 4 2 Soil pH and extractable macronutrients for the 15 30 cm. ................................ .. 42 4 3 Soil extractable Si and micronutrients for the 0 15 cm depth ............................. 43 4 4 Soil extractable Si and micronutrients for the 15 30 cm depth ........................... 44 5 1 Plant macronutrient concentrations determined across two sampling dates ...... 63 5 2 Plant Si and micronutrients determined across two sampling dates ................... 64 5 3 Millable stalks, KST, TSH and TCH response to elemental sulfur application. ... 65 5 4 Soil pH determined across four sampling dates in a study of sugarcane production on organic soil. ................................ ................................ .................. 66 5 5 Sugarcane leaf nutrient concentrations for two sampling and leaf nutrient critical values and optimum range 1 ................................ ................................ .... 6 7 5 6 Multiple regression models relating to soil pH and nutrient concentrations (mg dm 3 ) with TSH, and TCH. ................................ ................................ ........... 68 5 7 Multiple regression models relating to plant nutrient concentrations (% and mg kg 1 ) with TSH, and TCH ................................ ................................ ............... 68

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8 LIST OF FIGURES Figure page 2 1 Map of the Everglades Agricultural Area in south Florida. ................................ .. 20 4 1 Soil pH response to variable levels of Ca carbonate during the sugarcane growing season ................................ ................................ ................................ .. 45 4 2 Extractable NO 3 concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 46 4 3 Extractable NH 4 + concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 47 4 4 Elemental S effects on sulfate (SO 4 2+ ) concentration in organic soils varying in Ca carbonate contents (0%, 12.5%, and 50% by volume) .............................. 48 4 5 Extractable P concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 49 4 6 Extractable Mn concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 50 5 1 Leaf nitrogen concentration response to organic soil varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 69 5 2 Leaf phosphorus (P) response to organic soil varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ................................ ...... 70 5 3 Leaf potassium response to organic soil varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season. Error bars repre sent the standard error of the mean ................................ .................. 71 5 4 Leaf manganese (Mn) concentration in organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) ................................ ...................... 72

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9 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science ELEMENTAL SULFUR EFFECTS ON NUTRIENT AVAILABILITY IN ORGANIC SOIL HAVING VARIABLE CALCIUM CARBONATE By Avjinder Singh Kaler August 2013 Chair: J. Mabry McCray Co chair: John E. Erickson Major: Agronomy Organic soil subsidence is lowering the soil depth above the underlying limestone bedrock in the Everglades Agricultural Area. Incorporation of Ca carbonate into the root zone of soil from the underlying limestone increases pH and reduces availability of p hosphorus and micronutrients to crops. Elemental S has been recommended at a rate of 560 kg ha 1 at soil pH > 6.6 to reduce soil pH and therefore increase nutrient availability to crops. There is a need to determine the effectiveness of elemental S in cond itions of high pH and high Ca carbonate levels. The objective of this study was to determine elemental S effects on nutrient availability and sugarcane yield on organic soil having variable Ca carbonate content. A factorial pot experiment of 4 elemental S rates (0, 90,224, and 448 kg ha 1 ) and 3 organic soil types varying in added Ca carbonate (0%, 12.5%, and 50% by volume) was established using a randomized complete block design with four replications. Sulfur application had limited effects on soil pH redu ction and therefore failed to enhance nutrient availability. Sulfur application increased sulfate concentration in soils that could be at risk for export from the field. With increasing the Ca carbonate in soil, pH increased and nutrient availability

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10 decre ased, except for Mn. The expected reason for increased manganese availability was increased soil moisture associated with reducing conditions due to changes in physical properties of the soil with increased levels of Ca carbonate. High soil pH resulted in Mn and P deficiencies in the plants, and soil pH and Mn were important factors that influenced sugarcane yield.

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11 CHAPTER 1 BACKGROUND Sugarcane ( Saccharum spp.) is the most predominant row crop in south Florida with an approximate cultivation of 162,000 ha per year. About 80% part of this sugarcane is grown on the muck soil of Everglades Agricultural Area (EAA) (Morgan et al. 2009). The EAA, once wetlands, is an important agricultural region of 283,000 ha of land, which was drained in the early 1900s for agricultural production (Chen et al. 2006). The EAA soils are Histosols and typically contain 80% organic matter. These soils are high in nitrog en (N) content, but in their natural state are low in phosphorus (P) and micronutrient availability to crops. Five predominate soil series in the EAA are Dania, Lauderhill, Pahokee, Terra Ceia, and Torry. The Torry series is distinguished by having mineral content >35% and depth to limestone >130 cm. The other four soil series have <35% mineral content and are distinguished by depth to limestone, with Dania being shallowest (<50 cm) and Terra Ceia being deepest (>130 cm). Sugarcane is the most predominate c rop in the EAA. Like all other crops, sugarcane needs optimum nutrition from the soil for adequate growth and yield. Nutrients of particular concern for adequate nutrition for sugarcane in Florida soils are N, P, potassium (K), magnesium (Mg), boron (B), c opper (Cu), iron (Fe), manganese (Mn), silicon (Si), and zinc (Zn) (Rice et al. 2010). Each nutrient has their own specific role in crop production. Sugarcane production may be limited by the deficiency or overabundance of any of these nutrients and overa bundance of one nutrient may limit the uptake of others. For example, Zn availability can be limited due to high application of P fertilizers (Li et al. 2007). Thus, sensible use of fertilizers and/or amendments can

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12 improve nutrient balance in soil, resul ting in increased crop yield and enhanced fertilizer use efficiency. A major problem in the EAA is high pH of some organic soils, which reduces nutrient availability to crops, especially phosphorus and micronutrients and consequently affects the growth an d yield of the plants. Increased soil pH is mostly due to incorporation of calcium (Ca) carbonates from underlying limestone bedrock because of tillage operations for bed preparation and agricultural drainage (Snyder, 2005). Increased soil oxygen content, due to drainage and cultivation practices, hastens the decomposition of soil organic matter (SOM), which results in soil subsidence and decreased soil depth, thus increasing the influence from underlying limestone (CaCO 3 ) bedrock. Calcium carbonate, being the source of agricultural lime, increases the soil pH. The current soil subsidence rate is estimated at 0.6 inch per year (Wright and Snyder, 2009). Snyder, in 2005, predicted that in 2050 nearly half of EAA soil would have soils less than 8 inches in dep th, which will not be suitable for sugarcane production. Application of soluble micronutrient fertilizers to a soil high in Ca carbonate is ineffective because they are quickly bound in unavailable forms (Wiedenfeld, 2011). Soil pH adjustment is one of th e strategies that have been used to increase availability of pH sensitive nutrients. Elemental sulfur (S) application has been recommended to reduce soil pH and consequently increase nutrient availability to crops (Schueneman, 2001). The effectiveness of e lemental S to reduce soil pH depends upon the oxidation of elemental S into sulfate. The rate of oxidation depends upon some factors like the microbiological population in soil, soil environmental conditions including temperature, moisture and soil pH (Jag gi et al. 2005). Earlier recommendation of

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13 elemental sulfur application was 560 kg S/ha at pH > 6.6 to reduce soil pH (Anderson, 1985). Actual use of S is estimated to be much lower, 37 kg ha 1 per three years (Wright et al. 2008). Oxidation of organic s oils in the EAA can supply sufficient S requirement of sugarcane (Gilbert et al. 2012). Beverly and Anderson (1986) studied that soil pH reduction was only for a short term due to strong buffering capacity of EAA soils, which counteracts the acidification of S oxidation. Although the application of elemental S reduces soil pH and increases nutrient availability in alkaline soils, this response depends on the amount of calcium carbonates present in the soil that buffers the acidification of elemental S in t he soil (Lindemann et al. 1991). At one location of a field study with sugarcane, 448 kg S ha 1 failed to enhance nutrient availability and yield (Wright et al. 2009; Ye et al. 2010). However, McCray and Rice (2013) determined sugarcane yield response t o elemental S when pH was >7.2 in previous field studies. Therefore, there is a strong need to determine the effectiveness of elemental S in conditions of high pH and high Ca carbonate levels. Expanded elemental sulfur application to the calcareous soils of EAA could potentially cause more environmental problems in the Everglades wetland ecosystem. Increasing elemental sulfur application releases more P from the soils that may pose environmental problems like runoff and leaching of P into aquatic ecosystem (Santoso et al. 1995). Phosphorus is a major factor contributing to the deterioration of water quality and alteration of the Everglades wetland ecosystem (Childers et al. 2003). In addition, increased S application in the EAA could result in increased s ulfate levels in wetland ecosystems, which at particular sulfate concentrations stimulates the formation of methylmercury (Bates et al. 2002). Methylmercury (MeHg) is a neurotoxin which bio

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14 accumulates in higher organisms and can be found at high concentr ations in fish and other wildlife in the Everglades (Axelrad et al. 2009). There are some another sources of sulfate that can contribute to MeHg formation. These include microbial oxidation of soil organic sulfur (soil subsidence) and sulfate from Lake Ok eechobee (Bates et al. 2002; Gabriel et al. 2010). Application of elemental S should be evaluated in terms of effects on the sugarcane growth, which will provide for limited use of sulfur based on crop requirements. The objective of this study was to de termine the elemental sulfur effects on nutrient availability and sugarcane yield on organic soil having variable amounts of calcium carbonates. Objectives and Hypothesis The study was designed to determine the effects of elemental sulfur on sugarcane yield and macro micronutrient availability on organic soils with varying levels of calcium carbonate. The specific objectives and hypotheses were to: Determine elemental sulfur effects on soil pH and nutrient availability in organic soil having variable ca lcium carbonate levels. Hypothesis: Elemental S will reduce soil pH and consequently increase nutrient availability, but increasing calcium carbonates in the soil, will interact with the effect of elemental S. Determine sugarcane yield response and plant nutrient concentrations with elemental sulfur application in an organic soil varying in calcium carbonate content. Hypothesis: Sugarcane yield and nutrient concentrations will be enhanced with elemental S application. The completion of this study is expec ted to provide information about elemental sulfur effectiveness for sugarcane production and nutrient availability in conditions of high pH and high Ca carbonate levels in an organic soil of the EAA.

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15 CHAPTER 2 LITERATURE REVIEW History of Everglades Agricultural Area The EAA is an area of 283,000 ha of farmland, which is located in the south and east of Lake Okeechobee in South Florida (Fig. 1 1). Earlier, this area was wetlands, which were dominated by sawgrass prairies ( Cladium jamaicense ). Due to these flooding conditions, oxygen content was very low in the soil and was insufficient to maintain the functioning of aerobic microorganisms (Wright et al. 2009). In the early1900s, drainage of these wetlands allowed the conversion to agricultural use. T he soils of EAA are organic (Histosols) having organic matter content >30% and typically 80%. These soils are black in color, called muck soil because it was made up from humus primarily sawgrass due to drainage of swampland (Shih et al. 1998). After conv ersion into agricultural use, sugarcane ( Saccharum spp.) and winter vegetables have become dominate production crops in this area. These Histosols have formed over hard limestone bedrock. Five predominate soil series in the EAA are Dania, Lauderhill, Pahok ee, Terra Ceia, and Torry. The Torry series is distinguished by having mineral content >35% and depth to limestone >130 cm. The other four soil series have <35% mineral content and are distinguished by depth to limestone, with Dania being shallowest (<50 c m) and Terra Ceia being deepest (>130 cm). Drainage of the EAA resulted in soil aeration, which allowed organic matter decomposition (Chen et al. 2006). Soil subsidence occurs as organic soil oxidizes, resulting in decreased soil depth. As soil becomes ve ry shallow, pH generally increases as Ca carbonate from the underlying limestone is incorporated into the soil. Management of cultivation and irrigation also become more difficult with shallower soils (Wright et al. 2009).

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16 Importance of Sulfur Application Sulfur is an essential macronutrient that is required by all biological material. It plays an important role in vitamins and chlorophyll synthesis in plants. In addition, it is an intergral component of amino acids, cysteine and methionine (Kacar et al. 2007; Marschner, 1995). The role of sulfur in these processes emphasizes its importance as a nutrient for determining plant growth and development. Plant growth and yield are retarded with sulfur deficiency (Motior et al. 2011). Another use of sulfur is t o reduce soil pH when applied in elemental form. Application of elemental S in alkaline soil is very useful because it increases P availability by lowering soil pH so that P is less bound by Ca. Application of N, P, and K fertilizers under the unfavorable soil condition with high pH and calcium carbonates (Dawood et al. 1985; Neilsen et al. 1993) cannot resolve nutrient deficiency in the high pH soil. Wiedenfeld (2011) determined that sugarcane plant growth, as defined by leaf area index, responded to mod erate S application level, and sulfate, salinity and soil available P were increased by increasing the S level. Sulfur application in calcareous soils reduces the pH through oxidation of sulfur into sulfate by releasing hydrogen ions. Soil pH and moisture have important roles in the elemental sulfur oxidation. Under field conditions, the oxidation of elemental sulfur could be improved by providing the optimum soil moisture and temperature (Janzen et al. 1987; Jaggi et al. 1999; Jaggi et al. 2005). Microo rganisms including Thiobacillus bacteria oxidize elemental S into sulfate and hydrogen ions for energy which is produced in the reaction of S oxidation (Shadfan and Hussan, 1985; Yang et al. 2010). This decline in pH is a prime factor that regulates the n utrient uptake and hence crop growth and yield (Hilal and Abd Elfattah, 1987; Schueneman, 2001). Therefore, elemental sulfur may be used as a nutrient and soil acidifier (Neilson et al. 1993).

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17 Elemental Sulfur Application in EAA Everglades Agricultural A rea (EAA) soils are primarily Histosols with high organic matter content, typically 80% by weight (Snyder, 1978; Snyder, 2005). These soils in their natural state contain high N yet low P and micronutrient concentrations and hence require supplemental fert ilization. Different fractions of sulfur are found in EAA soil with organic and extractable sulfate comprising 87% and 13% of total sulfur, respectively (Ye et al. 2010). These soils formed when more organic matter (OM) production occurred than OM decompo sition due to limited oxygen availability for aerobic soil microorganisms, which converts the OM to carbon dioxide and water. Drainage of the EAA increased the oxygen in soil that is required for organic matter decomposition. As a result, soil subsidence ( lowering of soil surface elevation) occurred. With subsidence, as soils become shallow there is an incorporation of underlying limestone (CaCO 3 ) bedrock with soils by long term cultivation, resulting in increase of soil pH that is a problem for crop produc tion. Soil subsidence of Histosols can also result from shrinkage, compaction, and soil loss by wind erosion and burning. Wright and Snyder (2009) reported that the subsidence rate of soil is estimated at 0.6 inches yr 1 It is predicted that nearly half of EAA soil will be less than 8 inches deep to limestone in 2050 and hence will not be suitable for sugarcane production (Snyder 2005). Ye et al. (2009) determined that long term cultivation and management will significan tly alter the distribution and cycling of nutrients, microbial community composition, and activity in the EAA as soil subsidence continues. It has become a critical problem for EAA soils due to the shallow nature of many soils over the underlying limestone bedrock. Water high in calcium from Lake Okeechobee is transported through the subsurface and through

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18 irrigation canals into the root zones of the surface soil and so may be one of the reasons for soil pH increases in the EAA (Zhou and Li, 2001). The org anic soils of the EAA supply sufficient amounts of S for crop nutritional needs (Rice, 2010). High soil pH is the reason for elemental sulfur application in this area to reduce pH and increase nutrient availability. The current recommendation is 560 kg S h a 1 (Anderson,1985), but the effect of this dose was only for small time due to strong buffering capacity of the calcareous soils (Beverly and Anderson, 1986). High calcium carbonate level in soil counteracts the acidifying effects of elemental S oxidation making amendment effects temporary and minimally effective (Lindemann et al. 1991). Some previous studies showed the limited effects of elemental S on soil pH reduction and yield (Wright et al. 2009; Ye et al. 2010). However, McCray and Rice (2013) det ermined sugarcane yield response to elemental S when pH was >7.2 in previous field studies. Effects of Excessive Elemental Sulfur Application Excessive elemental sulfur application to the EAA soils may decrease soil pH for extended periods, but would not l ikely be economical for growers and may not be environmentally sustainable. Higher sulfur applications may cause pollution in the Everglades wetland ecosystem. Elemental sulfur applications for reducing soil pH release more P from soils that may increase r unoff and leaching of P from soil into aquatic ecosystems (Santoso et al. 1995; Jaggi et al. 2005). Increased P concentrations are the result of lowered pH and replacement of phosphate ions with sulfate ions on soil adsorption sites resulting in more ris k of P export from the fields. Childers et al. (2003) concluded that P is a major factor contributing to the deterioration of water quality and alteration of the Everglades wetland ecosystem. Sulfate contamination is an important

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19 factor in causing increase d mercury methylation in the Everglades (Benoit et al. 1999; Benoit et al. 2001; Bates et al. 2002; Gilmour et al. 2007; Orem et al. 2011). Increased S application in the EAA could result in increased sulfate levels in wetland ecosystems, which at par ticular sulfate concentrations stimulates the formation of methylmercury (Bates et al. 2002). The U.S. Geological Survey in South Florida has reported that the MeHg (neurotoxin) bioaccumulates in food chains through fish, and could be a risk to wildlife a nd humans who consume Everglades fish (Axelrad et al. 2011). Sulfur based agricultural fertilizers and amendments used in the EAA have been implicated as the major source of sulfate contamination in Everglades canals (Bates et al. 2002; Gabriel et al. 2 008). Gabriel et al. (2011) reported that microbial oxidation of soil organic sulfur and sulfate from Lake Okeechobee are other sources of sulfur in the Everglades wetlands ecosystem. Sulfate reducing bacteria (SRB) is the major producer of methyl mercury in aquatic ecosystems and methylation of inorganic mercury by SRB is dependent on sulfate availability (Ekstrom et al. 2003; Gilmour et al. 2004).The effect of sulfur on mercury methylation (MeHg) in the Everglades is determined by the balance between su lfate and sulfide (Benoit et al. 1999; Gilmour et al. 1992). Sulfide is also toxic to aquatic plants and animals (Axelrad et al. 2011). Axelrad et al. (2009) suggested that management of sulfate fertilizers and amendments in EAA soil is a potential opti on for reducing MeHg production and bioaccumulation.

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20 Fig ure 2 1. Map of the Everglades Agricultural Area in south Florida.

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21 CHAPTER 3 MATERIALS AND METHODS Site and Experiment D escription Everglades Research and Education Center (EREC) in Belle Glade. The EREC is located in the Everglades Agricultural Area in south Florida. Sugarcane and winter vegetables are the dominant crops grown in this area. My experiment consisted of a single outdoor pot study. This was a factorial experiment with two factors, three levels of added CaCO 3 (0%, 12.5%, and 50 % by volume) and four elemental S rates (0, 90, 224, 448 kg S ha 1 ) were arranged using a randomized complete block design with four replications. Shell rock was used for the CaCO 3 additions, which was thoroughly mixed in appropriate volumes with the entire soil for each pot. Particle size of shell rock fell into 5 grades by weight; 14% (>12.7 millimeters (mm)), 30% (12.7 2 mm), 15% (2 1 mm), 7% (1 0 .71 mm) and 34% (< 0.71 mm). Organic soil for the experiment was obtained from a field (47 CD 10SE) at EREC. Forty eight experimental units were obtained from the combination of two factors and their replications. Therefore, forty eight pots of 95L (25 gal lons) size were used to grow the sugarcane plants for this experiment. A single sugarcane ( Saccharum spp eye seed pieces in flats of the same organic soil used for the pots in December 2011 and then six seedlin gs were transplanted from the nursery to each pot in January 2012. A single furrow approximately 15 cm deep was formed in each pot in which all fertilizers were applied and then the seedlings were transplanted and the furrow was covered. Four rates of gran ular elemental S (90% S) were applied in a band in the furrow along with the other fertilizer. Other fertilizers were applied according to recommendation and

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22 guidelines for this region and soil type (Gilbert et al. 2012). All the fertilizers and elemental S were applied prior to planting and all pots received 29 kg P ha 1 as monoammonium phosphate, 139 kg K ha 1 as muriate of potash, and 39 kg micromix ha 1 (Mn, Zn, Cu, B). All calculations for fertilizer and S applications were based on the surface area o f the pot. No nitrogen was applied because sugarcane on muck soils does not require N fertilization (Rice et al. 2010). Water was applied two times a day through an automatic microjet irrigation system using well water. Pots had drainage holes on the side at the bottom. Weeds were removed by hand as necessary during the growing season. A support structure of cables was built outside each row of pots in August 2012 to prevent sugarcane lodging. S oil Sampling and A nalysis Soil Sampling Soil samples were take n at four times from each pot. The first soil sampling was carried out in January 2011 before planting and fertilization and the remaining three samples were taken in May 2012, August 2012, and January 2013. Six random soil cores were taken from each pot a t two depths, 0 15cm and 15 30 cm, with a soil sampling tube. After thoroughly mixing and removal of plant debris, samples were placed in properly labeled bags. Samples were air dried at 31C for three days, and then after sieving through 2mm screen, sampl es were put into labeled airtight cups prior to analysis.

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23 Soil pH 1 Soil pH was measured by using a soil to DI water ratio of 1:2 (15 cm 3 soil/30 mL DI water). After 10 minutes stirring and equilibrating for 1 hour, soil pH was measured on a pH meter. Mehli ch 3 Extraction 2 Mehlich 3 soil extraction was done using 2.5 cm 3 air dried soil/25 mL extracting solution in a 50 mL conical tube, which was then shaken for 5 minutes on a reciprocal shaker. The suspension was filtered through Whatman # 42 filter paper an d the extract was collected in a 20 mL scintillation vial. The extracts were analyzed using inductively coupled plasma atomic emission spectrometry (ICP) (Perkin Elmer Optima 5300, Shelton, CT) to determine Ca, Mg, K, Mn, Fe, Zn, and Cu concentrations. Col orimetric analysis was used for P analysis in the extract using a probe colorimeter (Brinkmann Model 950, Metrohm, Riverview, FL). The concentration of these nutrients was calculated in soil using the volume of the soil sample and extracting solution, expr essed as milligram per cubic decimeter (mg dm 3 ). Modified Acetic Acid Extraction 3 Acetic acid soil extraction was done using 10 cm 3 air dried soil/25 mL 0.5 N acetic acid in a 25 X 200 mm glass extraction tube. The soil and acetic acid were allowed to sta y in contact for 20 hours and then was shaken for 50 minutes on an end over end shaker. The suspension was filtered through Whatman # 42 filter paper and the extract was collected in a 20 ml scintillation vial. The extracts were analyzed using ICP to deter mine Ca, Mg, K, and Si concentrations. The concentration of these nutrients 1 (Wright et al. 2008) 2 (Mehlich, 1984) 3 (McCray et al. 2012)

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24 was calculated in soil using the volume of the soil sample and extracting solution, expressed as mg dm 3 2 M KCL Extraction 4 A 2 M KCl extraction was carried out for extractable a mmonium (NH 4 + ) and nitrate (NO 3 ) analysis in soil. This extraction used 2 g air dried soil/20 mL 2 M KCl in a 50 mL conical tube which was then shaken on reciprocal shaker for 1 hour. The suspension was filtered through Whatman # 42 filter paper and the extract was collected in a 20 mL scintillation vial. An AQ2 analyzer (Seal Analytical Inc., Mequon, WI ) was used to determine NO 3 concentrations and a spectrometer was used to determine NH 4 + concentrations. Values were in gravimetric form which were converted into volumetric (mg dm 3 ) form by using soil density which was determined for each pot. Water Ext raction 5 Water extraction was carried out to measure the sulfate (SO 4 2 ) concentration in soil using 3 g air dried soil/25 mL DI water in a 50 mL conical tube, which was then shaken on a reciprocal shaker for 30 mintues. The suspension was filtered through Whatman # 42 filter paper and the extract was collected in a 20 mL scintillation vial. Ion chromatography (Dionex ICS 5000) was used to analyze the sulfate concentration in soil. Values were in gravimetric form which were converted into volumetric (mg dm 3 ) form by using soil density. Plant Data Collection Plant data collection consisted of leaf sampling for tissue nutrient concentrations and harvest data. 4 (Castillo and Wright, 2008) 5 (Gharmakher et a l. 2009)

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25 Leaf Sampling Leaf sampling was taken at two times during the growing season. First sampling was in May 2012, and second was in August 2012. Ten top visible dewlap leaves were collected from each pot and then labeled with ribbon. After removing midribs from leaf blades, leaf blades were rinsed in DI water to remove soil and dust particles that may contam inate the samples. Rinsed samples were placed in paper bags for drying in the oven at 60C. Dried leaf samples were ground in a Wiley mill and after passing through 2 mm screen, ground leaf samples were collected in plastic bags for analysis. Nitric Acid D igestion Nitric acid digestion was carried out to determine concentrations of Ca, Mg, K, Mn, P, Fe, Zn, Cu, and S in leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.5 g of each sample into a 50 ml glass digestion tube. Boili ng chips and 10 mL of concentrated nitric acid were added into the tube with funnel on the mouth. The leaf material and nitric acid were allowed to stay in contact overnight for predigestion. The tubes were placed in a cold digestion block under a digestio n hood and digested for 2 hours at 150C and then 5 mL 30% hydrogen peroxide (H 2 O 2 ) was added. Again, the tubes were placed on the digestion block for half an hour at 110C. After dilution with DI water up to 25 mL in a tube, the digested solution was filt ered through Whatman # 42 filter paper into a 20 mL scintillation vial. The filtered solution was run on the ICP for determination of nutrient concentrations. Total Kjeldahl Nitrogen Digestion Total Kjeldahl Nitrogen digestion (TKN) was carried out to determine the total N concentration in leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.1 g of each sample into a 50 mL glass digestion tube. Boiling chips, one

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26 Kjeld ahl tablet (K 2 SO 4 + CuSO 4 ) and 3.5 mL of concentrated sulfuric acid were added to each tube. The tubes were placed on cold digestion block for 3.5 hours. After complete digestion, digested solution was diluted with DI water up to a 50 mL. Diluted solution was filtered through Whatman# 42 filter paper into a 20 ml scintillation vial. The filtered solution was run on the Lachat instrument for total N content in leaf tissue. Silicon Digestion Silicon digestion was carried out to determine the silicon content i n leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.1 g of each sample into a plastic centrifuge tube. Two mL 30% hydrogen peroxide (H 2 O 2 ) and 3 mL 50% sodium hydroxide were added to each tube, followed by gentle vortex each t ime after addition of solution. The tubes were placed in an autoclave at 15 psi for 30 minutes. After a complete digestion, 47 mL DI water was added to each tube for dilution. The diluted solution was filtered through Whatman # 42 filter paper into a 20 mL scintillation vial. A probe colorimeter was used to determine the Si concentration in leaf tissue. Harvest Data Harvest data was taken by cutting and weighing the sugar cane from each pot. Millable stalks were counted from the harvested sugarcane. After w eighing the sugarcane, the stalks were milled and crusher juice analyzed for Brix and Pol. Brix was measured using a temperature correcting refractometer. Pol was measured using a saccharimeter. Brix and Pol values were used to calculate the kg sucrose per ton cane (KST). The KST was determined according to the theoretical recoverable sugar method (Legendre, 1992). Tons cane ha 1 (TCH) was calculated from each pot by using pot diameter (0.6 m) as the row length and assumed row width as 1.5 m to allow for

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27 sh ading as in field conditions. Calculation of tons sucrose ha 1 (TSH) was made as the product of tons cane ha 1 (TCH) and KST (divided by 1000 to convert kg sucrose to metric tons) (McCray and Rice, 2013). Statistical Analysis All statistical analyses were performed using SAS version 9.3 and JMP 10. All the graphing was carried out on SigmaPlot 12.5. A mixed model was fit using restricted maximum likelihood in the GLIMMIX procedure of SAS (SAS Institute, Cary, NC). The fixed effects were S application rate, calcium carbonate levels, time, and their interaction, with block as a random effect. Analysis of variance was performed using significance at P<0.05. Degree of freedom was adju sted using the Kenward Roger adjustment. Pearson correlation analysis was performed to assess relationships between variables using PROC CORR. Stepwise multiple regressions were used to evaluate the relative importance of extractable nutrients in predictin g sugarcane yield.

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28 CHAPTER 4 ELEMENTAL SULFUR EFFECTS ON SOIL pH AND NUTRIENT AVAILABILITY IN HISTOSOLS HAVING VARIABLE CALCIUM CARBONATE LEVELS Introduction High pH and excessive CaCO 3 reduce the availability of phosphorus (P) and micronutrients t o crops. Poor nutrient availability rather than low total nutrient content in the soil is one of the major factors causing plant nutrient deficiency as observed in alkaline soils. Nutrient deficiencies limit the growth and yield of the crop (McCray and Ric e, 2013). Sensible use of fertilizers or/and amendments can improve nutrient balance in soil. In the Everglades Agricultural Area (EAA), soils are organic (Histosols) having organic matter content >30% and typically 80%. These soils are high in nitrogen (N ) content, but in their natural state have low available P and micronutrient concentrations (Rice et al. 2010). These soils developed as wetlands, which were dominated by sawgrass prairies ( Cladium jamaicense ). Due to these flooding conditions, oxygen con tent was very low in the soil, and insufficient to maintain the functioning of aerobic microorganisms. Therefore, the rates of organic matter accumulation exceeded the decomposition rates above the limestone bedrock (Wright et al. 2009). In the early1900s drainage of these wetlands allowed the conversion to agricultural use. Drainage of the EAA resulted in soil aeration which allowed more organic matter decomposition than accumulation (Chen et al. 2006), and has led to decreases in soil depth above the l imestone bedrock. This soil loss is referred as soil subsidence. The current estimated rate of soil subsidence is 0.6 inch per year (Wright and Snyder, 2009). As soils becomes shallow, management of cultivation and irrigation become more difficult (Wright et al. 2009).

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29 Sugarcane ( Saccharum spp.) is the most predominant row crop in south Florida with an approximate cultivation of 162,000 ha per year. About 80% part of this sugarcane is grown on the muck soil of the EAA (Morgan et al. 2009). High soil pH is a major problem in this area, which reduces nutrient availability to crops, especially phosphorus and micronutrients and consequently affects the growth and yield of the plants. Increased soil pH is mostly due to incorporation of calcium (Ca) carbonates f rom underlying limestone bedrock in shallow soils because of tillage operations for bed preparation and agricultural drainage (Snyder, 2005). Soil subsidence increases the influence from underlying limestone (CaCO 3 ) bedrock. Calcium carbonate, being the so urce of agricultural lime, increases the soil pH. Soil pH adjustment is one of the strategies that have been used to increase availability of pH sensitive nutrients. Elemental sulfur (S) application has been recommended at the rate of 560 kg S ha 1 at pH > 6.6 to reduce soil pH (Anderson, 1985). Actual use of S is estimated to be much lower, 37 kg ha 1 per three years (Wright et al. 2008). Beverly and Anderson (1986) determined that soil pH reduction was only for a short term due to strong buffering capaci ty of EAA soils, which counteracts the acidification of S oxidation. Although the application of elemental S reduces soil pH and increases nutrient availability in alkaline soils, this response depends on the amount of calcium carbonates present in the soi l that buffers the acidification of elemental S in the soil (Lindemann et al. 1991). At one location of a field study with sugarcane, 448 kg S ha 1 failed to enhance nutrient availability and yield (Wright et al. 2009; Ye et al. 2010). However, McCray and Rice (2013) determined sugarcane yield response to elemental S when pH was > 7.2 in

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30 previous field studies. Therefore, there is a strong need to f urther define the effectiveness of elemental S in conditions of high pH and high Ca carbonate levels. Expanded elemental sulfur application to the calcareous soils of EAA could potentially cause more environmental problems in the Everglades wetland ecosyst em. Increasing elemental sulfur application releases more P from the soils that may pose environmental problems from runoff and leaching of P into aquatic ecosystems (Santoso et al. 1995). Phosphorus is a major factor contributing to the deterioration of water quality and alteration of the Everglades wetland ecosystem (Childers et al. 2003). In addition, increased S application in the EAA could result in increased sulfate levels in wetland ecosystems, which at particular sulfate concentrations stimulates the formation of methylmercury (Bates et al. 2002). Methylmercury (MeHg) is a neurotoxin which bio accumulates in higher organisms and is found at high concentrations in fish. It could be a risk to wildlife and humans that consume Everglades fish (Axelrad et al. 2011). Application of elemental S should be evaluated in terms of effects on sugarcane growth, which will provide for limited use of sulfur based on crop requirements. The objective of this study was to determine elemental sulfur effects on soil p H and nutrient availability in organic soil having variable calcium carbonate levels. Materials and Methods Site Description Everglades Research and Education Center (EREC) in Belle Gl ade, FL. The experiment was a factorial experiment with two factors, three levels of added CaCO 3 (0%, 12.5%, and 50% by volume) and four elemental S rates (0, 90, 224, 448 kg S ha 1 ) were arranged using a randomized complete block design with four replicat ions (48

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31 experimental units). Shell rock was used for the CaCO 3 additions, which was thoroughly mixed in appropriate volumes with the entire soil for each pot (95L pots). Organic soil for the experiment was obtained from a field (47 CD 10SE) at EREC. A sin gle sugarcane ( Saccharum spp. eye seed pieces in flats of the same organic soil used for the pots in December 2011 and then six seedlings were transplanted from the nursery to each pot in January 2012. A singl e furrow approximately 15 cm deep was formed in each pot in which all fertilizers were applied and then the seedlings were transplanted and the furrow was covered. Four rates of granular elemental S (90% S) were applied in a band in the furrow along with t he other fertilizer. Other fertilizers were applied according to recommendation and guidelines for this region and soil type (Gilbert et al. 2012). All the fertilizers and elemental S were applied prior to planting and all pots received 29 kg P ha 1 as mo noammonium phosphate, 139 kg potassium (K) ha 1 as muriate of potash, and 39 kg micromix ha 1 (containing manganese (Mn), zinc (Zn), copper (Cu), and boron (B)). All calculations for fertilizer and S applications were based on the surface area of the pot. No nitrogen was applied because sugarcane on muck soils does not require N fertilization (Rice et al. 2010). Water was applied two times a day through an automatic microjet irrigation system using well water. Pots had drainage holes on the side at the bot tom. Weeds were removed by hand as necessary during the growing season. A support structure of cables was built outside each row of pots in August 2012 to prevent sugarcane lodging. Soil Sampling and Analysis Soil samples were taken four times from each po t. The first soil sampling was carried out in January 2011 before planting and fertilization and the remaining three

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32 samples were taken in May 2012, August 2012, and January 2013. Six random soil cores were taken from each pot at two depths (0 15 cm) and ( 15 30 cm) with a soil sampling tube. After thoroughly mixing and removal of plant debris, samples were placed in bags. Samples were air dried at 31C for three days, and then after being sieved through 2mm screen, samples were placed into the labeled airti ght cups prior to analysis. Soil pH was measured by using a soil to DI water ratio of 1:2 (15 cm 3 soil/30 mL DI water). After 10 minutes stirring and equilibrating for 1 hour, soil pH was measured on a pH meter (Ye et al. 2011). Extractable ammonium (NH 4 + ) and nitrate (NO 3 ) were measured by using 2 M KCL extraction in a ratio of 1:10 of dried soil (2 g) to extractant (20 mL). An AQ2 analyzer (NO 3 ) and spectrometer (NH 4 + ) were used to analyze the concentration of these nutrients in soil (Castillo and Wrig ht 2008). Water extraction was used to determine the sulfate concentration by using 3 g soil in 25 ml DI water, followed by ion chromatography (Gharmakher et al. 2009). Mehlich 3 extraction was used to determine the concentration of Ca, magnesium (Mg), K, P, Mn, iron (Fe), Zn, and Cu by using 2.5 cm 3 soil in 25 ml extractant (Mehlich, 1984). Acetic acid extraction was used to determine the concentration of Ca, Mg, K, and silicon (Si) by using 10 cm 3 soil in 25 ml extractant (McCray et al. 2012). Inductive ly coupled plasma atomic emission spectrometry (ICP) was used to analyze the nutrient concentration in soil for Mehlich 3 and acetic acid extractions. Statistical Analysis All statistical analyses were performed using SAS version 9.3 and JMP 10. All the graphing was carried out on SigmaPlot 12.5. A mixed model was fit using restricted maximum likelihood in the GLIMMIX procedure of SAS (SAS Institute, Cary, NC). The

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33 fixed eff ects were S application rate, calcium carbonate levels, time, and their interaction, with block as a random effect. Analysis of variance was performed using significance at P < 0. 05. Degree of freedom was adjusted using the Kenward Roger adjustment. Pearson correlation analysis was performed to assess relationships between variables using PROC CORR. Results and Discussion Soil pH Soil pH was not significantly affected by elemental S application at any CaCO 3 level for any sample date for the 0 15 cm depth (Table 4 1) or for the 15 30 cm depth (Table 4 2). Even pH in the soil with no added CaCO 3 was not significantly affected by the highest rate of elemental S application (448 kg ha 1 ). A limited soil pH reduction by S application may be due to the presence of high buffering capacity in soil against the acidification of S oxidation (Jaggi et al. 2005; Ye et al. 2011). High soil pH before S application indicates the presence of high Ca carbonate and bicarbonate content in soil, which buffers the S acidification (Rogovska et al. 2007). The range of pH for these soils prior to S application was 7.5 to 7.7, which typically causes reduced availability of P and micronutrients. This rate of S recommendation was made many years ago, when soil pH was lower. Now soil conditions has been changed and pH of some these soils has been increased. Therefore, highest higher rate of S application may be required to reduce pH in these soils. Soil pH wa s significantly increased with increased CaCO 3 level in soil at either depth (Table 4 1 and Table 4 2). Increased CaCO 3 raised the carbonate and bicarbonate concentration in soil, which was the reason for increased pH. There was a significant interaction b etween time and CaCO 3 for soil pH. Highest soil pH (7.74)

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34 was found in 50% CaCO 3 organic soil at 13 months and lowest (7.29) was with no added CaCO 3 at 4 months for the depth 0 15 cm (Fig. 4 1). Reduction of soil pH at 4 months was likely due to uptake of certain nutrients like NH 4 + and nitrification, which reduce the pH in the rhizosphere (Bolan et al. 1991). In this study, NH 4 + content in soil sharply decreased after planting, and was negatively correlated with soil pH (r 2 = 0.52) that means increasing the NH 4 + in soils would decrease soil pH. A previous study also showed limited soil pH reduction with S application (Ye et al. 2011). However, McCray and Rice (2013) showed pH decreases in the row with banded S application. Extractable Nitrogen No signi ficant elemental S effects were observed on extractable nitrate (NO 3 ) and ammonium (NH 4 + ) concentrations for any level of CaCO 3 at either depth (Table 4 1 and Table 4 2). Limited effects of S application on extractable NO 3 and NH 4 + may be due to low rate of S application, which did not change the soil pH (Ye et al. 2011). Usually, the entire N requirement for sugarcane in the EAA comes from the oxidation of organic soils (Rice et al. 2010). The concentration of extractable NO 3 was significantly higher in soil with no added CaCO 3 than soil with 50% CaCO 3 for the depth 0 15 cm (Table 4 1). However, extractable NH 4 + was significantly reduced with increased level of CaCO 3 in organic soils (Table 4 1). Low concentration of NO 3 and NH 4 + with increased level of CaCO 3 in organic soil might be due to the decrease in organic matter content with increased volume of CaCO 3 which led to the decreased oxidation of organic soils and hence lower concentrations of NO 3 and NH 4 + Extractable NO 3 was sharply decreased fr om 0 (10 12 mg dm 3 ) to 4 months (1.5 2.0 mg dm 3 ), and then remained near the same level throughout the growing season and had significant interaction with time (Fig. 4 2). However, extractable NH 4 + concentration fluctuated throughout the

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35 growing season and did not show any significant interaction with time (Fig. 4 3). The sharp decrease in NO 3 concentration at the 4 months sampling was likely due to the plant uptake and leaching losses. A fluctuation of ammonium may be due to plant uptake, which decreas ed its level in soil, and oxidation of organic soil, which increased its levels in soil, (Ye et al. 2011). Extractable Sulfate Elemental S application significantly increased extractable sulfate (SO 4 2 ) concentration in organic soils at the 0 15 cm depth (P>F = <0.001) (Table 4 1) and similar results were determined for the 15 30 cm depth (Table 4 2). Its concentration was highest in soil with no added CaCO3 with highest elemental S rates (448 kg ha 1 ) (Fig. 4 4). Increased CaCO 3 level in organic soils si gnificantly reduced extractable SO 4 2 concentration (P>F = < 0.001) (Table 4 1). There was a significant interaction between CaCO 3 and time for sulfate (P>F = < 0.001) (Table 4 1). Averaged across treatments, extractable SO 4 2 concentration was higher in s oils at first soil sampling (324 mg dm 3 ) and then, similar to nitrate, its concentration sharply decreased in 4 months (75 mg dm 3 ), and then increased slightly to 13 months (88 mg dm 3 ). Oxidation of elemental S in organic soils increases the extractable SO 4 2 concentration, therefore higher the rate of S application, higher the sulfate concentration in soil. The mineralization of organic soil is the other source of SO 4 2 in these soils and provides sufficient nutritional S for sugarcane in these soils (R ice et al. 2010). Low concentration of SO 4 2 with increased level of CaCO 3 in soils might be due to decreased organic matter content with increased volume of CaCO 3 which led to the decreased oxidation of organic soils and hence lower concentrations of SO 4 2 Similar to nitrate, low SO 4 2 concentration at 4 months was likely due to plant uptake and leaching losses and similar results were also

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36 observed by Ye et al. (2011). High SO 4 2 concentration in soil from oxidation of elemental S and organic soil are likely to increase the risk of sulfate export from fields and could be an environmental problem in the wetlands ecosystem (Gabriel et al. 2011). Extractable Phosphorus Mehlich 3 extractable P was not significantly affected by sulfur application at any Ca carbonate level for any sample date for the 0 15 cm depth (Fig. 4 1) or for the 15 30 cm depth (Table 4 2). Extractable P concentration was significantly decreased with increased CaCO 3 level in organic soils (P > F = <0.001) (Table 4 1). There was a signi ficant interaction between CaCO 3 and time for P (P > F = <0.001) and, averaged across treatments, its concentration decreased in organic soils as the growing season progressed (Fig. 4 5). Similar results were determined for the 15 30 cm depth (Table 4 2). Limited soil pH reduction by elemental S application did not influence the extractable P concentration in organic soil. Soil pH was increased with increased level of CaCO 3 in organic soils, which resulted in decreased extractable P. High CaCO 3 concentratio n in soils resulted in P adsorption with Ca and Mg, which made it unavailable for plant uptake (Wright and Snyder, 2009; Wright et al. 2012). High soil pH in EAA soils will limit P availability to sugarcane. Reduction of P concentration as the growing sea son progressed was likely due to plant uptake and leaching losses (Ye et al. 2011). Extractable Calcium, Magnesium, and Potassium Mehlich 3 extractable Ca, Mg, and K were not affected by the application of elemental S at any Ca carbonate level for any sam ple date for the 0 15 cm depth (Fig. 4 1) or for the 15 30 cm depth (Table 4 2). Mehlich 3 extractable Ca concentration was significantly increased with increased level of CaCO 3 in organic soils at each depth (Tables 4 1 and 4 2). However, Mehlich 3 extrac table Mg and K were significantly

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37 decreased with increased level of CaCO 3 in organic soils at each depth (Tables 4 1 and 4 2). Seasonal fluctuation of all these nutrient concentrations was observed in soils. Difference in soil pH may not necessarily change the concentration of Ca, Mg, and K. Any change in pH caused by S application would have been very localized because of the band application, and so the larger volume of soil would have been unaffected in terms of influence on other nutrients. Thus, S appl ication in organic soils showed limited effects on the concentrations of extractable Ca, Mg, and K. Increased concentration of Ca was likely due to release of Ca from the CaCO 3 and organic soil. However, increased volume of CaCO 3 decreased the organic matt er content in soils, which resulted in lower concentrations of Mg and K per volume of soil. The other likely reason of lower concentration of Mg and K with increased level of CaCO 3 was the competition with Ca in soils. Correlation of Ca with these nutrients revealed that both Mg (r 2 = 0.45) and K (r 2 = 0.56) were negatively correlated with Ca in soils, which means increasing the one would decrease the other. Seasonal fluctuation of these nutrient concentrations in soils may be due to plant uptake and leaching losses and oxidation of organic soils (Ye et al. 2011). Extractable Manganese Manganese is a micronutrient, which is highly influenced by the high pH of calcareous soils. Man ganese concentration was not significantly affected by S application in organic soils during the sugarcane growing season at either depth (Tables 4 3 and 4 4). Usually soil pH increases with CaCO 3 content, which consequently decreases the Mn availability i n soils. Unexpected results of Mn concentration were observed with CaCO 3 Extractable Mn increased with increasing level of CaCO 3 at each depth (Tables 4 3 and 4 4). Averaged across treatments for the 0 15 cm depth, Mn

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38 concentration was significantly decre ased after the first soil sampling to 4 months, then increased to 8 months, followed by a slight decrease at 13 months in all three soils varying in added CaCO 3 (Fig. 4 6). No change in Mn availability in soils with S application was likely due to limited soil pH reduction by elemental S oxidation. High buffering capacity of organic soils counteracted the acidification of S oxidation (Ye et al. 2011). Increased extractable Mn concentration in soils with increased CaCO 3 level is probably due to the changes in the physical properties of the soil with added CaCO 3 Added CaCO 3 decreased the volume of organic matter in the soil and likely increased the bulk density of the soil. Increased bulk density was indicated from the increased density of air dried soil. Th e increased density caused by the higher CaCO 3 levels resulted in reduced water infiltration rates, which were observed with added CaCO 3 particularly at the 50% CaCO 3 level. The lower infiltration rates and associated poorer drainage resulted in periods o f increased soil moisture including short periods of flooding with the added CaCO 3 treatments. Restricted aeration due to poor drainage or compaction increased reducing conditions in organic soils, which increased Mn availability in soils (Weil et al. 199 7). Increased leaf Mn concentrations have been consistently determined for samples taken during the rainy summer months in Florida compared to the drier spring, which have been attributed to differences in soil moisture (McCray et al. 2009). Plant uptake, leaching losses and oxidation of organic soils might be the reasons of seasonal fluctuation of Mn in soils. Extractable Iron, Zinc, and Copper Similar to Mn, extractable Fe, Zn, and Cu are also highly influenced by high pH in calcareous soils. Applicati on of elemental S did not significantly influence extractable Fe, Zn, and Cu concentrations in organic soils varying in CaCO 3 level during the

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39 growing season at either depth (Tables 4 3 and 4 4). Extractable Fe, Zn, and Cu concentrations were significantly decreased with increased level of CaCO 3 in soils at each depth (Tables 4 3 and 4 4). Similar to Mn, limited soil pH reduction by S application did not influence the Fe, Zn, and Cu availability in soils (Ye et al. 2011). Increased CaCO 3 level in soils inc reased soil pH and resulted in decreased Fe, Zn, and Cu availability in soils (Wright et al. 2012). Averaged across treatments, there were significant differences in sampling time for these nutrients at each depth (Tables 4 3 and 4 4). There may be many r easons for this difference such as plant uptake, leaching losses, high soil pH and high CaCO 3 and, oxidation of organic soils. Extractable Silicon Acetic acid extractable Si concentration was not significantly affected by S application at any Ca carbonate level in soils for any sample date for the 0 15 cm depth (Table 4 3) or for the 15 30 cm depth (Table 4 4). Increased CaCO 3 level in soils decreased the availability of Si in soils at each depth (Tables 4 3 and 4 4). There were significant differences in Si concentration among sampling times (Table 4 3). Averaged across treatments, Si concentration was significantly decreased from 4 (36.1 mg dm 3 ) to 8 months (30.7 mg dm 3 ), then increased to 13 months (35.8 mg dm 3 ). No effects of S application on Si conc entration were likely due to limited soil pH reduction. High soil pH and high extractable Ca due to increased CaCO 3 level in soils are likely reasons for decreased Si availability in soils. The results showed that Si was negatively correlated with soil pH (r 2 = 0.56) and Ca concentration (r 2 = 0.89) at the 0 15 cm depth, which means increasing one would decrease the other. Similar results were found for the soil depth 15 30 cm.

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40 Conclusions Soil pH was not affected by different rates of elemental sulfur a pplication. Limited effects of elemental S application on soil pH were likely due to strong buffering capacity of these organic soils, which counteracted the acidification of S oxidation. Consequently, application of elemental S failed to enhance the nutri ent availability in soil. In addition, sulfur application increased sulfate concentration in the soils that could be at risk for export from the field. However, increased level of CaCO 3 in organic soils raised the soil pH and hence decreased nutrient avail ability in soil, except for Mn. The unexpected results of increased Mn availability with increased CaCO 3 levels are associated with reducing conditions, which were due to the changes in the physical properties of the soil with added CaCO 3 High bulk densit y caused by added CaCO 3 decreased water infiltration rates in soils, which led to increases in soil moisture. Increased soil moisture enhanced the reducing conditions in soils, which consequently increased Mn availability. The increased soil pH brought abo ut by CaCO 3 additions likely increased the capacity of these soils to resist pH changes by S oxidation. New sulfur recommendation for these soils may be needed, but it should be evaluated in terms of effects on the plant growth and adverse environmental ef fects.

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41 Table 4 1. Soil pH and extractable macronutrients for the 0 15 cm depth determined across four sampling dates in a study of sugarcane on organic soil 1 pH NO 3 NH 4 + P SO 4 2 K Ca Mg S Rate (kg S ha 1 ) mg dm 3 0 7.55A 2 3.18A 25.5A 17.6AB 100.3B 93.1B 13995A 1380A 90 7.56A 3.09A 25.6A 18.1AB 96.0B 96.6AB 14230A 1395A 224 7.54A 3.57A 26.6A 17.2B 103.9B 98.8AB 14122A 1391A 448 7.54A 3.42A 26.5A 19.8A 151.7A 105.1A 14220A 1398A P>F 0.94 0.57 0.92 0.21 <.001 0.22 0.62 0.75 S Rate X Time (P>F) 0.74 0.7 0.77 0.62 0.55 0.9 0.46 0.8 CaCO 3 Added (%) 0 7.44C 3.9A 36.5A 25.2A 190A 112.6A 10795C 1525A 12.5 7.54B 3.3AB 30.6B 20.1B 153B 109.8B 12814B 1410B 50 7.66A 2.7B 14.0C 10.9C 84C 74.9C 19488A 1240C P>F <0.001 0.003 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Time (P>F) <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 CaCO 3 X Time (P>F) < 0.001 0.008 0.27 0.001 <0.001 0.03 <0.001 <0.001 S Rate X CaCO 3 (P>F) 0.62 0.93 0.86 0.24 0.004 0.86 0.98 0.46 S Rate X CaCO 3 X Time (P>F) 0.85 0.72 0.363 0.42 0.04 0.8 0.7 0.97 1 Extractions with 2 M KCl (NO 3 and NH 4 + ), water (SO 4 2 ), and Mehlich 3 (P, K, Ca, and Mg) 2 Means with the same letters are not significantly different at

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42 Table 4 2. Soil pH and extractable macronutrients for the 15 30 cm depth determined across four sampling dates in a study of sugarcane on organic soil 1 pH NO 3 NH 4 + P SO 4 2 K Ca Mg S Rate (kg S ha 1 ) mg dm 3 0 7.50A 2 3.3A 25.9A 16.8A 121.2B 88.4A 13994A 1340A 90 7.51A 3.4A 28.1A 17.6A 115.6B 90.3A 14280A 1340A 224 7.50A 3.4A 27.4A 16.8A 114.5B 92.2A 14256A 1335A 448 7.49A 3.4A 28.1A 17.6A 182.3A 94.1A 14256A 1332A P >F 0.82 0.95 0.61 0.81 <0.001 0.75 0.78 0.99 S Rate X Time (P>F) 0.5 0.42 0.89 0.99 0.002 0.82 0.99 0.74 CaCO 3 Added (%) 0 7.34C 3.9A 38.4A 24.6A 190.4A 108.4A 10836C 1474A 12.5 7.51B 3.5A 32.5B 18.5B 158.8B 100.8A 12612B 1340B 50 7.62A 2.7B 14.2C 10.3C 84.6C 65.8B 19889A 1198C P>F < 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Time (P>F) < 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 CaCO 3 X Time (P>F) < 0.001 0.01 0.77 <0.001 <0.001 0.46 <0.001 <0.001 S Rate X CaCO 3 (P>F) 0.16 0.64 0.62 0.65 <0.001 0.29 0.4 0.31 S Rate X CaCO 3 X Time (P>F) 0.71 0.69 0.82 0.3 0.17 0.55 0.09 0.85 1 Extractions with 2 M KCl (NO 3 and NH 4 + ), water (SO 4 2 ), and Mehlich 3 (P, K, Ca, and Mg) 2 Means with the same letters are not significantly different at

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4 3 Table 4 3. Soil extractable Si and micronutrients for the 0 15 cm depth determined across four sampling dates in a study of sugarcane on organic soil 1 Si Fe Mn Zn Cu S Rate (kg S ha 1 ) mg dm 3 0 35.1A 2 259.8A 2.3B 9.3A 2.71A 90 33.8AB 256.0A 2.2B 9.1A 2.68A 224 34.0AB 259.2A 2.7A 9.4A 2.86A 448 32.5B 262.4A 2.4B 9.3A 2.65A P>F 0.09 0.65 0.06 0.66 0.39 S Rate X Time (P>F) 0.3 0.09 0.04 0.01 0.89 CaCO 3 Added (%) 0 54.5A 342.3A 1.7C 11.1A 3.1A 12.5 33.3B 285.6B 2.3B 10.4B 3.0A 50 18.8C 166.4C 3.3A 6.8C 2.1B P >F <0.001 <0.001 <0.001 <0.001 <0.001 Time (P>F) <0.001 <0.001 <0.001 <0.001 <0.001 CaCO 3 X Time (P>F) 0.03 <0.001 <0.001 <0.001 <0.001 S Rate X CaCO 3 (P>F ) 0.005 0.88 0.4 0.14 0.63 S Rate X CaCO 3 X Time (P>F) 0.11 0.48 0.4 0.62 0.95 1 Extractions with Acetic acid (Si) and Mehlich 3 (Mn, Fe, Zn, and Cu) 2 Means with the same letters are not significantly different at

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44 Table 4 4. Soil extractable Si and micronutrients for the 15 30 cm depth determined across four sampling dates in a study of sugarcane on organic soil 1 Si Fe Mn Zn Cu S Rate (kg S ha 1 ) mg dm 3 0 27.5A 2 257.8A 2.13A 8.5A 2.4A 90 25.0 B 255.4A 2.21A 8.4A 2.5A 224 26.7AB 255.7A 2.37A 8.5A 2.6A 448 25.1B 254.1A 2.25A 8.3A 2.5A P >F 0.047 0.97 0.31 0.78 0.41 S Rate X Time ( P >F) 0.33 0.76 0.18 0.24 0.63 CaCO 3 Added (%) 0 47.6A 342.3A 1.5C 10.9A 2.86A 12.5 24.0B 285.6B 2.1B 9.6B 2.81A 50 12.3C 156.3C 3.3A 5.5C 1.85B P >F <0.001 <0.001 <0.001 <0.001 <0.001 Time ( P >F) <0.001 <0.001 <0.001 <0.001 <0.001 CaCO 3 X Time ( P >F) < 0.001 0.01 0.001 0.04 0.057 S Rate X CaCO 3 ( P >F) 0.09 0.63 0.75 0.62 0.33 S Rate X CaCO 3 X Time ( P >F) 0.85 0.32 0.57 0.12 0.55 1 Extractions with Acetic acid (Si) and Mehlich 3 (Mn, Fe, Zn, and Cu) 2 Means with the same letters are not significantly different at

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45 Fig ure 4 1. Soil pH response to variable levels of Ca carbonate during the sugarcane growing season. Error bars represent the standard error of the mean

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46 Fig ure 4 2. Extractable NO 3 concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season for the depth 0 15 cm. Error bars represent the standard error of the mean

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47 Fig ure 4 3. Extracta ble NH 4 + concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season for the depth 0 15 cm. Error bars represent the standard error of the mean.

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48 Fig ure 4 4. Elemental S effects on sulfate (SO 4 2+ ) concentration in organic soils varying in Ca carbonate contents (0%, 12.5%, and 50% by volume). Error bars represent the standard error of the mean.

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49 Figure 4 5. Extractable P concentration in three organic so ils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season for the depth 0 15 cm. Error bars represent the standard error of the mean.

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50 Figure 4 6. Extractable Mn concentration in three organic soils varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season for the depth 0 15 cm. Error bars represent the standard error of the mean.

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51 CHAPTER 5 RESPONSE OF SUGARCANE YIELD AND PLANT NUTRIENT CONCENTRATIONS TO SULFUR AMENDED ORGANIC SOILS VARYING IN CALCIUM CARBONATE CONTENT Introduction Sugarcane ( Saccharum spp.) is the predominant row crop in south Florida with an approximate cultivation of 162,000 ha per year. About 80% of this sugarcane is grown on the muck soil of Everglades Agricultural Area (EAA) (Morgan et al. 2009). The EAA soils are Histosols and typically contain 80% organic matter. These soils are high in nitrogen (N) content, but in their natural state have low available phosphorus (P) and micronut rient concentrations. Nutrients of particular concern for adequate nutrition for sugarcane in Florida soils are N, P, potassium (K), magnesium (Mg), boron (B), copper (Cu), iron (Fe), manganese (Mn), silicon (Si), and zinc (Zn) (Rice et al. 2010). Each nu trient has their own specific role in crop production. Plant nutrient concentrations are highly influenced by the deficiency or overabundance of any of these nutrients and overabundance of one nutrient may limit the uptake of others. For example, Zn availa bility can be limited due to high application of P fertilizers (Li et al. 2007). Sensible use of fertilizers and/or amendments can improve nutrient balance in soil, resulting in increased crop yield and enhanced fertilizer use efficiency. High pH of organ ic soils in the EAA reduces nutrient availability to crops, especially phosphorus and micronutrients, and consequently affects the growth and yield of the plants. Increased soil pH is mostly due to incorporation of calcium (Ca) carbonates from underlying l imestone bedrock because of tillage operations for bed preparation and agricultural drainage (Snyder, 2005). Drainage and cultivation practices increase soil organic matter (SOM) decomposition, which results in soil subsidence and decreased soil depth, thu s

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52 increasing the influence from underlying limestone (CaCO 3 ) bedrock. Calcium carbonate, being the source of agricultural lime, increases the soil pH. The current soil subsidence rate is estimated at 0.6 inch/year (Wright and Snyder, 2009). Snyder, in 2005 predicted that in 2050 nearly half of EAA soil would have soils less than 8 inches in depth, which will not be suitable for sugarcane production. Soil pH adjustment is one of the strategies that have been used to increase availability of pH sensitive nu trients. Application of soluble micronutrient fertilizers to a soil high in Ca carbonate is ineffective because they are quickly bound in unavailable forms (Wiedenfeld, 2011). Elemental sulfur (S) application has been recommended to reduce soil pH and cons equently increase nutrient availability to crops (Schueneman, 2001). The effectiveness of elemental S to reduce soil pH depends upon the oxidation of elemental S into sulfate. The rate of oxidation depends upon factors like the microbiological populations in soil and environmental conditions including temperature, moisture and soil pH (Jaggi et al. 2005). An earlier recommendation of elemental sulfur application was 560 kg S/ha at pH > 6.6 to reduce soil pH (Anderson, 1985). Actual use of S is estimated to be much lower, 37 kg ha 1 per three years (Wright et al. 2008). Oxidation of organic soils in the EAA can supply sufficient S requirement of sugarcane (Gilbert et al. 2010). Beverly and Anderson (1986) determined that soil pH reduction was only for a sh ort term due to strong buffering capacity of EAA soils, which counteracts the acidification of S oxidation. Although the application of elemental S reduces soil pH and increases nutrient availability in alkaline soils, this response depends on the amount o f calcium carbonates present in the soil that buffers the acidification effects of elemental S (Lindemann et al. 1991). At one location of a field

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53 study with sugarcane, 448 kg S/ha failed to enhance nutrient availability and yield (Wright et al. 2009; Ye et al. 2010). However, McCray and Rice (2013) determined sugarcane yield response to elemental S when pH was >7.2 in previous field studies. Expanded elemental sulfur application to the calcareous soils of EAA could potentially cause environmental proble ms to the Everglades wetland ecosystem. Therefore, there is a strong need to determine the effectiveness of elemental S in conditions of high pH and high Ca carbonate levels. The objective of this study was to determine the elemental sulfur effects on suga rcane yield and plant nutrient concentrations on organic soil having variable amounts of calcium carbonate. Materials and Methods Site Description Everglades Research and Education Center (EREC) in Belle Glade. The experiment was a factorial experiment with two factors, three levels of added CaCO 3 (0%, 12.5%, and 50% by volume) and four elemental S rates (0, 90, 224, 448 kg S ha 1), which were arranged using a randomized complete blo ck design with four replications (48 experimental units). Shell rock was used for the CaCO3 additions, which was thoroughly mixed in appropriate volumes with the entire soil for each pot (95L or 25 gallon pots). Organic soil for the experiment was obtained from a field (47 CD 10SE) at eye seed pieces in flats of the same organic soil used for the pots in December 2011 and then six seedlings were transplanted from the nursery to each pot in January 2012. A single furrow approximately 15 cm deep was formed in each pot in which all fertilizers were applied and then the seedlings were transplanted and the furrow was covered. Four

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54 rates of granular elemental S (90% S) were applied in a band in the furrow along with the other fertilizer. Other fertilizers were applied according to recommendations and guidelines for this region and soil type (Gilbert et al. 2012). All the fertilizers and elemental S were applied prior to planting and all pots re ceived 29 kg P ha 1 as monoammonium phosphate, 139 kg K ha 1 as muriate of potash, and 39 kg micromix ha 1 (containing Mn, Zn, Cu, and B). All calculations for fertilizer and S applications were based on the surface area of the pot. No nitrogen was applied because sugarcane on muck soils does not require N fertilization (Rice et al. 2010). Water was applied two times a day through an automatic microjet irrigation system using well water. Pots had drainage holes on the side at the bottom. Weeds were removed by hand as necessary during the growing season. A support structure of cables was built outside each row of pots in August 2012 to prevent sugarcane lodging. Plant Data Collection Plant data collection consisted of leaf sampling for tissue nutrient concen trations and harvest data. Leaf Sampling Leaf sampling was done at two times during the growing season. The first sampling was in May 2012, and second was in August 2012. Ten top visible dewlap leaves were collected from each pot and then labeled with rib bon. After removing midribs from leaf blades, leaf blades were rinsed in DI water to remove soil and dust particles that may contaminate the samples. Rinsed samples were placed in paper bags for drying in the oven at 60C. Dried leaf samples were ground in a Wiley mill and after passing through 2 mm screen, ground leaf samples were stored in plastic bags.

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55 Nitric Acid Digestion Nitric acid digestion was carried out to determine concentrations of Ca, Mg, K, Mn, P, Fe, Zn, Cu, and S in leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.5 g into a 50 ml glass digestion tube. Boiling chips and 10 mL of concentrated nitric acid were added into the tube with funnel on the mouth. The leaf material and nitric acid were allowed to stay in contact overnight for pre digestion. The tubes were placed in a cold digestion block under a digestion hood and digested for 2 hours at 150C and then 5 mL 30% hydrogen peroxide (H2O2) was added. Again, the tubes were placed on the digestion block for half an hour at 110C. After dilution with DI water up to a 25 mL in a tube, the digested solution was filtered through Whatman # 42 filter paper into a 20 mL scintillation vial. The filtered solution was run on the ICP for determination of nutrient concentrat ions. Total Kjeldahl Nitrogen (TKN) Digestion A TKN digestion was carried out to determine the total N concentration in leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.1 g into a 50 mL glass digestion tube. Boiling chips, o ne Kjeldahl tablet (K2SO4 + CuSO4) and 3.5 mL of concentrated sulfuric acid were added to each tube. The tubes were placed on cold digestion block for 3.5 hours. After complete digestion, digested solution was diluted with DI water up to 50 mL. Diluted sol ution was filtered through Whatman# 42 filter paper into a 20 ml scintillation vial. The filtered solution was run on the Lachat instrument for total N content in leaf tissue. Silicon Digestion Silicon digestion was carried out to determine the silicon con tent in leaf tissue. Ground leaf samples were dried overnight at 65C before weighing 0.1 g of each

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56 sample into a plastic centrifuge tube. Two mL 30% hydrogen peroxide (H2O2) and 3 mL 50% sodium hydroxide were added to each tube, followed by gentle vortex each time after addition of solution. The tubes were placed in an autoclave at 15 psi for 30 minutes. After a complete digestion, 47 mL DI water was added to each tube for dilution. The diluted solution was filtered through Whatman # 42 filter paper into a 20 mL scintillation vial. A probe colorimeter was used to determine the Si concentration in leaf tissue. Harvest Data Harvest data was taken by cutting and weighing the sugar cane from each pot. Millable stalks were counted from the harvested sugarcane. After weighing the sugarcane, the stalks were milled and crusher juice analyzed for Brix and Pol. Brix was measured using a temperature correcting refractometer. Pol was measured using a saccharimeter. Brix and Pol values were used to calculate the kg sucr ose per ton cane (KST). The KST was determined according to the theoretical recoverable sugar method (Legendre, 1992). Tons cane ha 1 (TCH) was calculated from each pot by using pot diameter (0.6 m) as the row length and assumed row width as 1.5 m to allow for shading as in field conditions. Calculation of tons sucrose ha 1 (TSH) was made as the product of tons cane ha 1 (TCH) and KST (divided by 1000 to convert kg sucrose to metric tons) (McCray and Rice, 2013). Statistical Analysis All statistical analyse s were performed using SAS version 9.3 and JMP 10. All the graphing was carried out on SigmaPlot 12.5. A mixed model was fit using restricted maximum likelihood in the GLIMMIX procedure of SAS (SAS Institute, Cary, NC, USA). The fixed effects were S applic ation rate, calcium carbonate levels, time, and their

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57 interaction, with block as a random effect. Analysis of variance was performed using significance at P<0.05. Degree of free dom was adjusted using the Kenward Roger adjustment. Pearson correlation analysis was performed to assess relationships between variables using PROC CORR. Stepwise multiple regressions were used to evaluate the relative importance of soil pH and nutrients in predicting sugarcane yield. Results and Discussion Nitrogen There were no significant differences for leaf N concentration with sulfur application in organic soils varying in CaCO3 content during the growing season (Table 5 1). Significantly greater le af N concentration was observed in soil with no added crop requirement comes from the oxidation of organic soils (Rice et al. 2010). Low N concentration with added CaCO3 was likely due to a decrease in the volume of organic matter for oxidation, as well as increased soil pH and increased Ca concentration in soils, which decreased N availability in soils. Nitrogen concentration in leaves was negatively correlated with soil pH (r 2 = 0.62) and soil Ca concentration (r 2 = 0.45) Averaged across treatments, leaf N concentration was lower at May (1.7%) and August (1.4%) than the critical N value (1.8%) for sugarcane (Table 5 5). Leaf N concentration was highest for soil with no added CaCO3 in May and then significantly r educed in August in all treatments (Fig. 5 1). The reason for the reduced concentration was likely due to leaching losses of N from soil, which were observed in the soil N test (data not shown) (Ye et al. 2011).There was a significant interaction between CaCO3 and time for leaf N concentration (Fig. 5 1).

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58 Phosphorus There were no significant differences in leaf P concentration among treatments, which was not affected by S application at any level of CaCO 3 during the growing season (Table 5 1). This was l ikely due to limited soil pH reduction by the S treatments (Table 5 4) (Ye et al. 2011). There were also no significant differences in leaf P concentration with added CaCO 3 in organic soils (Table 5 1). Leaf P concentration was below the critical P value (0.19%) for sugarcane in May (0.15%) and then significantly increased in August (0.22%) (Table 5 5). Low P concentrations in the spring may be associated with drought stress in the spring with less rainfall as compared to summer. Sulfur, Calcium, Potassium and Magnesium Leaf S, Ca, K, and Mg concentrations were not affected by different rates of S application in organic soils (Table 5 1). The concentrations of all these nutrients were at or above the critical values for sugarcane at both sampling times (Ta ble 5 5). Leaf K concentration significantly decreased with added CaCO 3 (Table 5 1). There was a significant difference for leaf S between no added CaCO 3 soil and 12.5% CaCO 3 soil (Table 5 1). However, Ca and Mg did not show any significant effects of adde d CaCO 3 in soils. Calcium carbonate and time had significant interaction for leaf K concentration. Its concentration was highest for no added CaCO 3 soil in August sampling and lowest for 50% CaCO 3 soil in May sampling (Fig. 5 3). Increased volume of CaCO 3 increased the pH and Ca concentration in soil, and decreased the volume of organic matter, which were the reasons of low leaf K concentration. There was significant negative correlation of leaf K with soil pH (r 2 = 0.73) and soil Ca concentration (r 2 = 0.5 6), which indicates that increased soil pH and Ca concentration was associated with lower leaf K concentration.

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59 Manganese Sulfur amendment did not significantly enhance leaf Mn concentration (Table 5 2). This may be due to the limited effects of S applic ation on soil pH reduction (Table 5 4), so that Mn availability was similar across S treatments. Unexpected results of Mn concentration in plants were observed with CaCO 3 treatments. Increased level of CaCO 3 increased leaf Mn concentration (Table 5 2). Thi s was likely due to the change in physical characteristics of the soil with added CaCO 3 Added CaCO 3 increased bulk density of the soil by decreasing the volume of organic soil and consequently decreased the infiltration rates of water. Low infiltration le d to periodic flooding and poor drainage, and increased reducing conditions with added CaCO 3 These conditions resulted in increased leaf Mn concentration as has been observed with increased soil moisture in the summer rainy season in Florida (McCray et al. 2009). Leaf Mn concentration significantly increased with time in summer compared to spring (Fig. 5 4), but it was still within the deficient category for both sampling times, May (5.6 mg kg 1 ) and August (13.1 mg kg 1 ) (Table 5 5). Iron, Copper, and Zi nc Sulfur application in organic soils did not significantly influence leaf Fe, Cu, and Zn concentrations (Table 5 2). Leaf Cu and Zn concentrations were within the optimum range for sugarcane (Table 5 5). Averaged across treatments, leaf Fe concentration was below the critical Fe value for sugarcane in May, but leaf Fe concentration was within the optimum range for sugarcane in August (Table 5 5). Increased leaf Fe concentration in August was likely due to the rainy season, which increased the soil moistu re and reducing conditions and consequently increased Fe availability in August (McCray et al. 2009). Increased level of CaCO 3 did not significantly influence the leaf

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60 Fe, Cu, and Zn concentrations (Table 5 2). Leaf Fe and Cu concentrations significantly increased from May to August (Table 5 5). However, leaf Zn concentration did not show any significant difference across the growing season (Table 5 5). Silicon Sulfur amendment did not affect leaf Si concentrations in organic soils during the growing season (Table 5 2). Leaf Si concentration was within the optimum range for sugarcane (Table 5 5). There was a significant difference for leaf Si among organic soils varying in added CaCO 3 content (Table 5 2). Leaf Si was significantly decreased in August c ompared to May (Table 5 5). Millable Stalks There were no significant differences among the treatments for millable stalks. Sulfur application in organic soils did not affect the millable stalk numbers, and variation in CaCO 3 rates did not influence the mi llable stalks number (Table 5 3). This lack of an effect on millable stalks might be due to the limited effects of S application and CaCO 3 levels on the nutrient availability in soils. Sugarcane Yield Sulfur application did not significantly affect the yie ld parameters kg sucrose t 1 cane (KST), t cane ha 1 (TCH), or t sucrose ha 1 (TSH) (Table 5 3). This can be explained by the lack of pH change in soils with S application. There also were no significant differences in TCH or TSH among CaCO 3 treatments. Y ield Predictor Multiple regression models were developed to determine the important factors in soil and plants that could be used to predict the yield of TSH and TCH (Table 5 6 and Table 5 7). Soil pH before planting and fertilization was the important fac tor, which

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61 influenced the yield of TSH and TCH (Table 5 6). Soil pH showed negative relation to yield which means increased soil pH would decrease the sugar yield. In plants, K and Cu concentrations in May were important factors which influenced the yield (Table 5 7). Negative relation of K concentration with yield might not be its direct effects on yield reduction. This could be due to the influence of K on other nutrients like Mn or covariance with other factors. In our study, negative correlation of plan t K and soil Mn concentration indicated that leaf K concentration increased as leaf Mn decreased (r 2 = 0.56). Thus, Mn concentration may be the predictor which indirectly influences the yield. There were low coefficient of determinations for TSH and TCH for both soil and plant, which indicates that factors which influences the yields were not quantified (Anderson et al. 1999). These linear models gave only rough approximations of the relationships between the factors and yield (Anderson et al. 1999 and Ye et al. 2011). Conclusions Sulfur application at different rates in organic soils did not affect p lant nutrient concentrations. Limited effects of elemental S application were likely due to limited reduction of soil pH, which consequently did not influence nutrient availability to sugarcane. Variable CaCO 3 in soils did not show any significant effects on plant nutrient concentrations except Mn. The unexpected results of increased plant Mn concentration are associated with increased soil Mn availability with increased CaCO 3 levels. Increased CaCO 3 levels enhanced the reducing conditions, which were due t o the changes in the physical properties of the soil with added CaCO 3 Added CaCO 3 in organic soils increased bulk density and decreased water infiltration rates in soils, which led to increases in water retention, soil moisture which led to development of anaerobic reducing conditions. The reducing conditions solubilized Mn and increased its Mn

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62 availability, thus leaf Mn concentrations increased. Sulfur application and CaCO 3 levels did not significantly influence sugarcane yield parameters KST, TSH or TCH due to limited changes in nutrient concentrations. All the soil available nutrients were within optimum range except for P, Fe, and Mn, which indicate that high soil pH reduces P, Fe and Mn availability to crops. Subsequently, soil pH, P and Mn were the mo st important predictors of sugarcane yield.

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63 Table 5 1. Plant macronutrient concentrations determined across two sampling dates in a study of sugarcane production on organic soil 1 N P S K Ca Mg S Rate (kg S ha 1 ) % 0 1.56 A 2 0.190 A 0.15 A 1.28 A 0.33 A 0.19 A 90 1.59 A 0.194 A 0.16 A 1.32 A 0.33 A 0.19 A 224 1.57 A 0.193 A 0.15 A 1.30 A 0.34 A 0.19 A 448 1.48 A 0.187 A 0.15 A 1.30 A 0.33 A 0.18 A P >F 0.39 0.7 0.59 0.85 0.99 0.77 S Rate X Time ( P >F) 0.98 0.17 0.57 0.72 0.89 0.89 CaCO 3 Added (%) 0 1.73 A 0.20 A 0.159 A 1.44 A 0.32 A 0.19 A 12.5 1.44 B 0.186 B 0.145 B 1.25 B 0.34 A 0.19 A 50 1.47 B 0.189 AB 0.149 AB 1.22 B 0.34 A 0.18 A P >F <0.001 0.07 0.04 <0.001 0.24 0.29 Time ( P >F) <0.001 <0.001 <0.001 <0.001 <0.001 < 0.001 CaCO 3 X Time ( P >F) <0.001 0.12 0.31 0.001 0.55 0.68 S Rate X CaCO 3 ( P >F) 0.72 0.36 0.71 0.39 0.59 0.86 S Rate X CaCO 3 X Time ( P >F) 0.81 0.12 0.26 0.51 0.56 0.69 1 Digestion with Nitric acid (P, K, S, Ca, and Mg), and Total Kjeldahl Nitrogen (N) 2 Means with the same letters are not significantly different 0.05

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64 Table 5 2. Plant Si and micronutrients determined across two sampling dates in a study of sugarcane production on organic soil 1 Si Fe Mn Zn Cu S Rate (kg S ha 1 ) % mg kg 1 0 1.08A 2 59.4A 9.2A 15.9A 5.9A 90 1.11A 59.6A 8.1A 19.1A 5.8A 224 1.04A 59.9A 9.5A 19.8A 6.0A 448 1.14A 61.4A 9.1A 19.6A 5.7A P >F 0.45 0.82 0.55 0.34 0.45 S Rate X Time ( P >F) 0.98 0.87 0.09 0.89 0.69 CaCO 3 Added (%) 0 0.91B 60.0AB 6.2B 19.9A 6.0A 12.5 1.18A 62.2A 10.3A 17.6A 5.8A 50 1.19A 58.0B 10.7A 18.3A 5.7A P >F <0.001 0.11 <0.001 0.51 0.28 Time ( P >F) 0.01 <0.001 <0.001 0.6 <0.001 CaCO 3 X Time ( P >F) 0.41 0.57 0.006 0.92 0.002 S Rate X CaCO 3 ( P >F) 0.47 0.31 0.53 0.53 0.11 S Rate X CaCO 3 X Time ( P >F) 0.15 0.25 0.38 0.92 0.049 1 Digestion with Nitric acid (Mn, Fe, Cu and Zn), and Silicon (Si) 2 Means with

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65 Table 5 3. Millable stalks, KST, TSH and TCH response to elemental sulfur application in a study of sugarcane production on organic soil varying in Ca carbonate levels 1 Millable stalks KST TSH TCH S Rate (kg S ha 1 ) 0 10A 2 129.8A 17.2A 118.9A 90 10A 131.2A 15.6A 106.7A 224 10A 130.1A 15.7A 108.7A 448 10A 129.4A 15.5A 107.6A P >F 0.92 0.6 0.83 0.8 CaCO 3 Added (%) 0 9A 128.5B 14.4B 100.8A 12.5 11A 131.5A 18.2B 124.2A 50 10A 130.3AB 15.5AB 106.8A P >F 0.29 0.045 0.11 0.14 S Rate X CaCO 3 ( P >F) 0.56 0.39 0.45 0.45 1 KST (kg sucrose t 1 cane), TSH ( t sucrose ha 1 ), and TCH ( t cane ha 1 ) 2 = 0.05

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66 Table 5 4. Soil pH determined across four sampling dates in a study of sugarcane production on organic soil. 0 15 cm 15 30 cm S Rate (kg S ha 1) 0 7.55 A 1 7.50 A 90 7.56 A 7.51 A 224 7.54 A 7.50 A 448 7.54 A 7.49 A P >F 0.94 0.82 S Rate X Time ( P >F) 0.74 0.5 CaCO 3 Added (%) 0 7.44 C 7.34 C 12.5 7.54 B 7.51 B 50 7.66 A 7.62 A P >F <0.001 <0.001 Time ( P >F) <0.001 <0.001 CaCO 3 X Time ( P >F) <0.001 <0.001 S Rate X CaCO 3 ( P >F) 0.62 0.16 S Rate X CaCO 3 X Time ( P >F) 0.85 0.71 1 Means with the same letters are not significantly different at

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67 Table 5 5. Sugarcane leaf nutrient concentrations for two sampling and leaf nutrient critical values and optimum range 1 Nutrient May August Critical Value Optimum Range % Nitrogen (N) 1.70A 2 1.40B 1.8 2.00 2.60 Phosphorus (P) 0.15B 0.22A 0.19 0.22 0.30 Potassium (K) 1.00B 1.7A 0.9 1.00 1.60 Calcium (Ca) 0.22B 0.47A 0.2 0.20 0.45 Magnesium (Mg) 0.13B 0.25A 0.12 0.15 0.32 Sulfur (S) 0.13B 0.18A 0.13 0.13 0.18 Silicon (Si) 1.15A 1.03B 0.5 >0.70 mg kg 1 Iron (Fe) 44.4B 78.1A --------50 105 Manganese (Mn) 5.6B 13.1A --------20 100 Zinc (Zn) 18.1A 19.2A 15 16 32 Copper (Cu) 4.4B 7.5A 3 4.0 8.0 1 From Anderson and Bowen (1990), except for Si, McCray et al. (2010). All values are from Florida except S, which is from Louisiana. 2 0.05.

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68 Table 5 6. Multiple regression models relating to soil pH and nutrient concentrations 1 (mg dm 3 ) with TSH, and TCH 3 at different times 2 during the growing season. Yield (Y) Equation R 2 TSH Y= 294.2 15 pH (T0) + 0.0002 A Ca (T4) 0.31 TCH Y= 1087.8 50 pH (T0) 1.1*M P (T8) 0.28 1 Nutrients A Ca (Acetic acid calcium) and M P (Mehlich 3 phosphorus) 2 Time T0(before planting), T4 (4 months) and T8 (8 months) 3 TSH ( t sucrose ha 1 ), and TCH ( t cane ha 1 ) Table 5 7. Multiple regression models relating to plant nutrient concentrations 1 (% and mg kg 1 ) with TSH, and TCH 3 at different times 2 during the growing season Yield (Y) Equation R 2 TSH Y= 5.43 8.5* K (May) + 2.9*Cu (May) 0.56 TCH Y=33.4 55.3* K(May) + 19.7*Cu(May) 0.57 1 Nutrients K (potassium) and Cu (copper) 2 Time May sampling 3 TSH ( t sucrose ha 1 ), and TCH ( t cane ha 1 )

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69 Figure 5 1. Leaf nitrogen concentration response to organic soil varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season. Error bars represent the standard error of the mean

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70 Figure 5 2. Leaf phosphorus (P) response to organic soil varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season. Error bars represent the standard error of the mean

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71 Figure 5 3. Leaf potassium response to organic soi l varying in added Ca carbonate (0%, 12.5%, and 50% by volume) during the sugarcane growing season. Error bars represent the standard error of the mean

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72 Figure 5 4. Leaf manganese (Mn) concentration in organic soils varying in added Ca carbonate (0%, 12 .5%, and 50% by volume) during the sugarcane growing season. Error bars represent the standard error of the mean

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73 CHAPTER 6 S UMMARY Sulfur amendment did not significantly affect the soil pH due to the strong buffering capacity of t hese organic soils, which counteracted the acidification of S oxidation. Consequently, nutrient availability in the soils was not affected by the application of elemental sulfur. Increased sulfate concentration in the soils with S application could be at r isk for export from the field. However, the addition of CaCO 3 in soils increased the soil pH and consequently reduced the nutrient concentrations in soil, except for manganese (Mn). The expected reason of increased Mn availability with added CaCO 3 in soils are associated with an increase in reducing condition. This was likely due to the change in physical characteristics of the soil with added CaCO 3 Added CaCO 3 increased bulk density of the soil by decreasing the volume of organic soil which result ed in decreased the infiltration rates of water. Low infiltration led to periodic flooding and poor drainage, and increased reducing conditions with added CaCO 3 Similar in plants, leaf nutrient concentrations were not significantly affected by S amendment in organic soils which were likely due to a limited soil pH reduction with S application. Added CaCO 3 in soils did not show any significant effects on plant nutrient concentrations except Mn. Similarly, t he unexpected results of increased plant Mn concentration are associated with increased soil Mn availability due to increased reducing conditions. Sulfur amendment and variable CaCO 3 levels did not significantly influence sugarcane yield parameters KST, TSH or TCH due to limited changes in nutri ent concentrations. All the soil available nutrients were within optimum range except for P, Fe, and Mn, which indicate that high soil pH reduces P, Fe and Mn availability to crops. Subsequently, soil pH, P and Mn were the most important

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74 predictors of suga rcane yield. New sulfur recommendation for these soils may be needed, but it should be evaluated in terms of effects on the plant growth and adverse environmental effects.

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75 LIST OF REFERENCES Anderson, D.L. 1985. Crop soil fertility recommendations of the Everglades soil testing laboratory. EREC Belle Glade Report EV 1985 10. Belle Glade, FL: University of Florida. Anderson, D.L., K.N. Portier, T.A. Obreza, M.E. Collins and D.J. Pitts. 1999. Tree regression analysis t o determine effects of soil variability on sugarcane yields. Soil Sci. Soc. Am. J. 63:592 600. Axelrad, D.M., T. Lange, M. Gabriel and T.D. Atkeson. 2009. Chapter 3B: Mercury and sulfur monitoring, research and environmental assessment in South Florida. In: 2009 South Florida Environmental Report Volume I, South Florida Water Management District, West Palm Beach, FL. Axelrad, D.M., T. Lange, M. Gabriel and T.D. Atkeson. 2011. Chapter 3B: Mercury and sulfur monitoring, research and en vironmental assessment in South Florida. In: 2011 South Florida Environmental Report Volume I, South Florida Water Management District, West Palm Beach, FL. Bates, A.L., W.H. Orem, J.W. Harvey and E.C. Spiker 2002. Tracing sources of sulfur in the Flo rida Everglades. J. Environ. Qual. 31:287 299. Benoit, J.M., C.C. Gilmour, A. Heyes, R.P. Mason and C. Miller. 2003. Geochemical and biological controls over methylmercury production and degradation in aquatic ecosystems Y. Chai and O.C. Braids, eds. In: Biogeochemistry of Environmentally Important Trace Elements, pp. 262 297, ACS Symposium Series #835, American Chemical Society, Washington, D.C. Benoit, J.M., C.C. Gilmour, R.P. Mason and A. Heyes. 1999. Sulfide controls on mercury speciation and bioavai lability in sediment pore waters Environ Sci. Technol., 33:951 957. Benoit, J.M., R.P. Mason, C.C. Gilmour and G.R. Aiken. 2001. Constants for mercury binding by dissolved organic carbon isolates from the Florida Everglades. Geochim. Cosmochim. Acta 65:4 445 4451. Beverly, R.B. and D.L. Anderson. 1986. Effects of acid source on soil pH. Soil Sci.143:301 303. Bolan N.S., M.J. Hedley and R.E. White. 1991. Processes of soil acidification during nitrogen cycling with emphasis on legume based pastures. Plant and Soil 45:169 179 Castillo, M.S. and A.L. Wright. 2008. Soil phosphorus pools for Histosols under sugarcane and pasture in the Everglades, USA. Geoderma 145:130 135.

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76 Chen, M., S.H. Daroub, T. A. Lang, and O.A. Diaz. 2006. Specific conductance and ionic characteristics of farm canal in the Everglades Agricultural Area. J. Environ. Qual. 35:141 150. Childers, D.L., R.F. Doren, R. Jones, G.B. Noe, M. Rugge, and L. J. Scinto 2003. Decadal change in vegetation and soil phosphorus patterns across the Everglades landscape. J. Environ. Qual. 32:344 362. Dawood F., S.M. Al Omari and N. Murtatha. 1985. High levels of sulphur affecting availability of some micronutrients in calcareous soils. In Proc. Sec. Reg. Conf. on Sulphur and its Usage in Arab Countries, Riyadh 2 5 March 1985, Saudi Arabia. pp.55 68. Ekstrom, E.B., F.M.M. Morel and J.M. Benoit. 2003. Mercury methylation independent of the acetyl coenzyme a pathway in sulfate reducing bacteria Appl. Environ. Microbiol. 69(9):5414 5422. Gabriel, M.C., G. Redfi eld and D. Rumbold. 2008. Appendix 3B 2: Sulfur as a regional water quality concern in South Florida. In: 2008 South Florida Environmental Report Volume I, South Florida Water Management District, West Palm Beach, FL. Gabriel, M.C., M. Axelrad, T. A. Lan ge, and L. Dirk. 2011. Chapter 3B: Mercury and sulfur monitoring, research and environmental assessment in South Florida. 2010 South Florida Environmental Report. South Florida Water Management District, West Palm Beach, FL. Gharmakher, H.N., J.M. Machet, N. Beaudoin and S. Recous 2009. Estimation of sulfur mineralization and relationships with nitrogen and carbon in soils. Biol. Fert. Soils. 45:297 304. Gilbert R.A., R.W. Rice and D. C. Odero. 2012. Nutrient requirements for sugarcane production on Florida muck soils Florida Cooperative Extension Service Fact Sheet SS AGR 228. UF/IFAS Electronic Data Information Source (EDIS) Database. Available at http://edis.ifas.ufl.edu/sc026. University of Florida, Gainesville. Gilmour, C.C., D. Krabbenhoft, W. Orem and G. Aiken. 2004. Appendix 2B 1: Influence of drying and rewetting on mercury and sulfur cycling in Everglades and STA soils In: 2004 Everglades Consolidated Report. South Florida Water Management District, West Palm Beach, FL. Gilmour, C.C., E.A. Henry and R. Mitchell. 1992. Sulfate stimulation of mercury methylation in freshwater sediments. Environ. Sci. Technol., 26:2287 2294.

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77 Gilmour, C.C., W. Orem, D. Krabbenhoft and I.A. Mendelssohn. 2007. Preliminary assessment of sulfur sources, trends a nd effects in the Everglades. In: 2007 South Florida Environmental Report, Appendix 3B 3, South Florida Water Management District, West Palm Beach, FL. Hilal M.H. and A.A. Abd Elfattah. 1987. Effect of CaCO3 and clay content of alkali soils on their respo nse to added sulphur. Sulphur Agric. 11:15 17 Jaggi, R.C., M.S. Aulakh and R. Sharma. 1999. Temperature effects on soil organic sulfur mineralization and elemental sulfur oxidation in subtropical soils of varying pH. Nutr. Cycl. Agroecosys. 54:175 182. Ja ggi, R.C., M.S. Aulakh and R. Sharma. 2005. Impacts of elemental S applied under various temperature and moisture regions on pH and available P in acidic, neutral and alkaline soils. Biol. Fert. Soils. 41:52 58. Janzen, H.H. and J. R. Bettany. 1987 Measu rement of sulfur oxidation in soils. Soil Sci. 143:444 452. Kacar B. and A.V. Katkat. 2007. Plant Nutrition. 3th Edn. Nobel Press; Ankara, Turkey. Legendre, B.L. 1992. The core/press method for predicting the sugar yield from cane for use in cane payment Sugar J., 54:2 7. Lindemann, W.C., J.J. Aburto, W.M. Haffner and A.A. Bono. 1991. Effect of sulfur source on sulfur oxidation. Soil Sci. Soc. Am. J. 55:85 90. Marschner, H. 1995. Mineral nutrition of higher plants 2nd. ed. Academic Pres; San Diago, USA Mehlich, A. 1984. Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant. Commun. Soil Sci. Plant Anal, 15:1409 1416. McCray, J. M., S. Ji, G. Powell, G. Montes, R. Perdomo, and Y. Luo. 2009. Seasonal concentrations of leaf nutrients in Fl orida sugarcane. Sugar Cane International 27(1):17 24. McCray, J. M., and S. Ji. 2012. Calibration of sugarcane response to calcium silicate on Florida Histosols. J. Plant Nutrition 35:1192 1209. McCray, J.M., and R.W. Rice. 2013. Sugarcane yield response t o elemental sulfur on high pH organic soils. Proc. International Soc. Sugar Cane Technologists. In press. Morgan, K.T., J.M. McCray, R.W. Rice, R.A. Gilbert and L.E. Baucum. 2009. Review of current sugarcane fertilizer recommendations: A report from the UF/IFAS sugarcane fertilizer standards task force. UF EDIS SL 295, Gainesville, FL.

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78 Motior, M.R., A.S. Abdou, H.A.D. Fareed and M.A. Sofian. 2011. Responses of sulfur, nitrogen and irrigation water on Zea mays growth and nutrients uptake. Aust. J. Crop Sc i. 5(3):347 357. Neilsen, D., E.J. Hogue, P.B. Hoyt and B.G. Drought. 1993. Oxidation of elemental sulfur and acidification of calcareous orchard soils in southern British Columbia. Can. J. Soil Sci. 73:103 114. Orem, W., Gilmour, Cynthia, Axelrad, Donald Krabbenhoft, David, Scheidt, Daniel, Kalla, Peter, McCormick, Paul, Gabriel, Mark and George. 2011. Sulfur in the South Florida ecosystem: distribution, sources, biogeochemistry, impacts, and management for restoration' Crit. Rev. Env. Sci. Technol. 41 :6, 249 288 Rice, R.W., R.A. Gilbert and J.M. McCray. 2010. Nutrient requirements for Florida sugarcane. UF IFAS SS AGR 228, Gainesville, FL. Rogovska, N.P., A.M. Blackmer and A.P. Mallarino. 2007. Relationships between soybean yield, soil pH, and soil c arbonate concentration. Soil Sci. Soc. Am. J. 71:1251 1256. Santoso, D., R.D.B. Lefroy and G.J. Blair. 1995. A comparison of sulfur extractions for weathered acid soils. Aust. J. Soil. Res. 33:125 133. Schueneman, T.J. 2001. Characterization of sulfur sou rces in the EAA. Soil and Crop Soc. Fla. Proc. 60:49 52. Shadfan H. and A.A. Husssen. 1985. Effect of sulphur application on the availability of P, Fe, Mn, Zn and Cu in selected Saudi soils. In: Proc. Sec. Reg. Conf. on Sulphur and Its Usage in Arab Count ries. Riyadh 2 5 March, 1985, Saudi Arabia. 1:3 24. Shih, S. F., B. Glaz and R. E. Barns. 1998. Subsidence of organic soils in the Everglades Agricultural Area during the past 19 years. Soil and Crop Soc. Fla. Proc. 57:20 29. Snyder, G. H. 2005. Everglades Agricultural Area soil subsidence and land use projections. Soil and Crop Soc. Fla. Proc. 64:44 51. Snyder, G.H., H.W. Burdine, J.R. Crockett, G.J. Gascho, D.S. Harrison, G. Kidder and J.W. Mishoe. 1978. Water table management for organi c soil conservation and crop production in the Florida Everglades. Florida Agricultural Experiment Stations Bulletin, 801, Univ. of Florida, Gainesville, FL. Weil R.R., C.D. Foy and C.A. Coradetti. 1997. Influence of soil moisture regimes on subsequent so il manganese availability and toxicity in two cotton genotypes Agron. J. Vol. 89:1 8.

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79 Wiedenfeld, B. 2011. Sulfur application effects on soil properties in a calcareous soil and on sugarcane growth and yield. J. Plant Nutrition 34:7, 1003 1013 Wright, A. L. and G.H. Snyder. 2009. Soil subsidence in the Everglades Agricultural Area. SL 311, Soil and Water Science Dept., Florida Cooperative Extension Service, IFAS, University of Florida. Wright, A.L., Y. Wang and K.R. Reddy. 2008. Loss on ignition method t o assess soil organic carbon in calcareous Everglades wetlands. Commun. Soil. Sci. Plan. 39:3074 3083. Wright, A.L., E.A. Hanlon and R. Rice. (2012). Managing pH in the Everglades agricultural soils. Florida Cooperative Extension Service Fact Sheet SL 287 UF/IFAS Electronic Data Information Source (EDIS) Database. Available at http://edis.ifas.ufl.edu/SS500. Univ. of Florida, Gainesville. Yang Z.H., K. Stoven, S. Haneklaus, B.R. Singh and E. Schnug. 2010. Elemental sulfur oxidation by Thiobacillus spp. a nd aerobic Heterotrophic Sulfur Oxidizing bacteria Pedosphere 20(1):71 79, Ye, R., A.L. Wright, K. Inglett, Y. Wang, A.V. Ogram and K.R. Reddy. 2009. Land use effects on soil nutrient cycling and microbial community dynamics in the Everglades Agricultura l Area, Florida. Commun. Soil. Sci. Plan 40: 2725 2742. Ye, R., A.L. Wright, W.H. Orem and J.M. McCray, 2010. Sulfur distribution and transformations in Everglades Agricultural Area soil as influenced by sulfur amendment Soil Sci. 175:263 26 Ye, R., A.L Wright, J.M. McCray, K.R. Reddy, and L. Young. 2010. Sulfur induced changes in phosphorus distribution in Everglades Agricultural Area soils. Nutr. Cycl. Agroecosys. 87:127 135. Ye, R., A.L. Wright and J.M. McCray. 2011. Seasonal changes in nutrient ava ilability for sulfur amended Everglades soils under sugarcane J. Plant Nutrition, 34:2095 2113. Zhou, M., and Y. Li. 2001. Phosphorus sorption characteristics of calcareous soils and limestone from the southern Everglades and adjacent farmlands. Soil Sci. Soc. Am. J. 65:1404 1412.

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80 BIOGRAPHICAL SKETCH Avjinder Singh Kaler was born in 1989 in Punjab, India. He is the youngest son of Jaswinder Kaur and Nirmal Singh. He attended school at G.H.G National Public School, Pakhowal. He earned a Bachelor of Science with Honors in Agriculture with a major in plant breeding and genetics from Punjab Agricultural University, India in 2011 In 2011, he was enrolled in the graduate program of the Agronomy Department at the University of Florida. He graduated in August 2013 with a MS in agronomy and a minor in soil and water science.