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Vertical mobility and dynamics of phosphorus from fertilizer and manure in sandy soils

University of Florida Institutional Repository
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PAGE 1

VERTICAL MOBILITY AND DYNAM ICS OF PHOSPHORUS FROM FERTILIZER AND MANURE IN SANDY SOILS By LEIGHTON CROFT WALKER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004

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Copyright 2004 by Leighton Croft Walker

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This document is dedicated to my parents Mr. Herbert Walker and Mrs. Valerie Walker.

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ACKNOWLEDGMENTS Thanks go to my committee Dr. D. Graetz (chair), Dr. V.D. Nair (cochair), Dr. W. Harris and Dr. R. Nordstedt for working arduously with me and providing me the necessary guidance in completing this research. I would also like to thank my laboratory manager Mrs. Dawn Lucas and my fellow lab mates and colleagues in the department. The warm support of my parents Mr. Herbert Walker and Mrs. Valerie Walker, and my siblings Denver, Kerry, Shajni and Allistair and their families was a major motivational factor. My fiance and soon to be wife Sonia was also very supportive for which I was especially appreciative. Above everyone else, I thank my God and Creator without whom there would not be even a possibility of starting or even completing this degree. iv

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TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES............................................................................................................vii LIST OF FIGURES...........................................................................................................ix ABSTRACT.........................................................................................................................x CHAPTER 1 INTRODUCTION........................................................................................................1 2 LITERATURE REVIEW.............................................................................................4 3 MATERIALS AND METHODS...............................................................................20 Soils............................................................................................................................20 Column Leaching Study.............................................................................................21 Column Setup.............................................................................................................21 Analytical Procedures.................................................................................................25 Soil Analysis........................................................................................................25 P Source/ Amendment Analysis..........................................................................25 Leachate Analysis................................................................................................26 Water Treatment Residual Analysis....................................................................26 Soil Fractionation................................................................................................26 Statistical Analyses..............................................................................................28 4 RESULTS AND DISCUSSION.................................................................................30 Soil Characterization..................................................................................................30 Amendment Characterization.....................................................................................31 Leachate Characterization..........................................................................................31 pH........................................................................................................................31 Electrical Conductivity........................................................................................37 Phosphorus..........................................................................................................41 Fractionation...............................................................................................................45 5 CONCLUSION...........................................................................................................53 v

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APPENDIX A PHOSPHORUS CONCENTRATIONS OF FERTILIZERS AND MANURES AND THE QUANTITIES OF EACH APPLIED TO EACH SOIL COLUMN.......55 B PERCENT CHANGES IN SOIL PHOSPHORUS FRACTIONS OBSERVED THE FOR BYRD DAIRY AND OAK GROVE SOILS............................................56 C PHOSPHORUS CONCENTRATIONS FOR THE BYRD DAIRY AND OAK GROVE LEACHATES..............................................................................................64 LIST OF REFERENCES...................................................................................................68 BIOGRAPHICAL SKETCH.............................................................................................75 vi

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LIST OF TABLES Table page 3-1 Chemical components of simulated rainwater.........................................................22 4-1 Selected Chemical Properties of the Ap Horizons of the Byrd Dairy and Oak Grove Dairy soils (n = 6).................................................................30 4-2 Selected properties of the Al-WTR used in the study (OConnor and Elliot, 2000).......................................................................................................31 4-3 Phosphorus fractions, oxalate extractable P, Fe, and Al and P sorbing capacity of the Al-WTR (OConnor and Elliot, 2000)................................31 4-4 p values for Hydronium ion concentrations of the Byrd Dairy and Oak Grove soil column leachates for the 1 st leaching event.............................32 4-5 Average pH values of the Byrd Dairy soil column leachates for the 1 st leaching event................................................................................................32 4-6 p values for Hydronium ion concentrations of the Byrd Dairy and Oak Grove soil column leachates for the 19 th leaching event...........................33 4-7 Average pH values of the Byrd Dairy soil column leachates for the 19 th leaching event....................................................................................................33 4-8 Average pH values of the Oak Grove soil column leachates for the 1 st leaching event......................................................................................................35 4-9 Average pH values of the Oak Grove soil column leachates for the 19 th leaching event.........................................................................................................................35 4-10 SRP amounts leached from BD and OG soils over 19 leaching events...................43 4-11 TP amounts leached from BD and OG soils over 19 leaching events.....................43 4-12 p values for interactions for the BD soil. (P = 0.05)................................................46 4-13 Sequential data for amounts of P (g P/g) in the soil P fractions in the Byrd Dairy soil...................................................................................................48 4-14 p values for interactions for the OG soil (P=0.05)...................................................50 vii

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4-15 Sequential data for amounts of P (g P) in the soil P fractions in the Oak Grove soil.........................................................................................................52 viii

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LIST OF FIGURES Figure page 3-1 Diagram of leaching column containing soil and treatment....................................24 3-2 Schematic of the modified fractionation procedure adopted from Hedley et al. (1982).......................................................................................................................29 4-1 Trends in pH changes observed for theByrd Dairy soil. (A) Amended column leachates. (B) Unamended column leachates...........................................................34 4-2 Trends in pH changes observed for the Oak Grove soil. (A) Amended column leachates. (B) Unamended column leachates...........................................................36 4-3 Average electrical conductivity values for leachates collected from columns containing different P source treatments for the Byrd Dairy soil. (A) Amended column leachates. (B) Unamended column leachates..............................................38 4-4 Average electrical conductivity values for leachates collected from columns containing different P source treatments for the Oak Grove soil. (A) Amended column leachates. (B) Unamended column leachates..............................................39 ix

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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 VERTICAL MOBILITY AND DYNAMICS OF PHOSPHORUS FROM FERTILIZER AND MANURE SOURCES IN SANDY SOILS By Leighton Croft Walker May 2004 Chair: D.A. Graetz Cochair: V.D. Nair Major Department: Soil and Water Science Animal manures from intensive livestock operations are rich sources of nutrients such as phosphorus (P) which are vital for plant growth. Increased amounts of P in water bodies may lead to unwanted environmental and aesthetic damages to these aquatic ecosystems. Some types of land-applied animal manures may release P even more easily than commercial P fertilizers when in contact with rainwater. The coarse textured sandy soils of Florida are prone to losing P both by surface runoff and leaching down through the soil profile. A column leaching study was conducted on coarse textured sandy soils with different nutrient management histories (high and low impact by manures) from two commercial dairy farms. Soil columns were treated with three P sources (dairy storage pond effluent, inorganic fertilizer and broiler litter compost), each applied at a rate equivalent to 40 kg P ha -1 The objective of this study was to compare the leaching potential of the three P sources applied to low and highly manure-impacted sandy soils, and also to evaluate the effects of an aluminum based water treatment residual (WTR) on x

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P leaching. Soil columns (25cm L 7.5 cm I.D.) were leached with simulated rainfall over a 19 week period. Leachate was collected at each leaching event, and at the end of the study, the soil was sectioned into three depth increments to evaluate the movement of P within the column. The low manure impacted soil leached overall approximately five times less P than the highly impacted soil. The dairy storage pond effluent treated soils leached P more easily and in greater amounts than the remaining soil treatments. Leachates of dairy storage pond effluent treated soils had higher electrical conductivity (EC) and pH valeus than the leachates of the remaining treatments. The Al-WTR reduced the quantities of P leached within P source treatments of the low manure impacted soil by 18-33% and from the high impact soil P source treatments (excluding the control) by 16-22%. It was, however, less effective at reducing the quantities of P leached from dairy effluent treated soil columns when compared to the remaining P sources. The soil columns containing the added Al-WTR had significantly (P = 0.05) greater quantities of soil P stored as the stable iron (Fe) and aluminum Al bound P. xi

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CHAPTER 1 INTRODUCTION The increasing number of intensive cattle and poultry operations in the United States (US) is creating ever increasing amounts of manures as by-products. Manures are very rich in nutrients which can be utilized as fertilizers for crop production. Some manure types may even as effective as commercially available chemical fertilizers at providing P to crops. Land application rates of these manures needs to be tailored according to the respective soils and crops receiving them in order to ensure optimal agronomic and environmental benefits. Nitrogen (N) and phosphorus (P), two major nutrients in these manures, are a major concern with regard to water quality. Eutrophication, which results from the over enrichment of water bodies with these nutrients, is a major problem. Eutrophication is an excessive growth of plant biomass in water bodies in response to excesses of N and P (Perzynski et al., 2000). This has a number of undesirable effects on the quality of aquatic systems, the chief one being the rapid exhaustion of dissolved oxygen (DO). The levels of DO in these waters are rapidly depleted when plants die and microbes use the DO in the decomposition of the dead plant material. Unavailability of DO is detrimental for aquatic animals resulting in disastrous ecological effects such as fish kills. Eutrophication of water bodies may have numerous other negative effects, such as elimination of desired plant and animal species, disruption of aquatic food chain, and even loss of aesthetic and recreational value of water bodies. Excessive N loss from agricultural operations to water bodies has long been treated in the US as a potential source of environmental pollution. As a result of this, agronomic 1

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2 recommendations were being made on an N basis. Levels of P were not being considered for some time, and soils were being loaded with P unnoticed (McDowell et al., 2001; Sharpley et al., 1994). It is clearly evident that the eutrophication process is dependent on both nutrients. Florida has many intensive livestock operations, particularly poultry and dairy farms, which create large quantities of animal manures rich in P as wastes which are land-applied to grow hay and other crops. Application of manures to soils that have low P retention capacity, as in the case of many soils in Florida, increases the potential of P loss from land application of manures. Currently, a P risk assessment index is being developed to determine the vulnerability of manure application sites in order to minimize harmful environmental impacts (Nair and Graetz, 2002). Of paramount importance in developing this P-index is an understanding of the dynamics, availability and movement of P from manures as compared to fertilizers to the environment. Increasing retentive capacity of soils by using soil amendments is also a very promising and useful possibility (Anderson et al., 1995; Callahan et al., 2002; Codling et al., 2002). Although leaching or movement of P vertically through soil profiles has generally not been considered an environmental issue, recent studies have shown that leaching of P can occur in some soils. This is particularly true in coarse textured soils with low P retention capacity. Inorganic chemical fertilizers have generally been thought of as being more at risk of losing P to the environment (Emeades, 2003). However, it has been shown that P may leach more readily from animal manures than from commercial fertilizers (Eghball et al., 1996).

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3 Water treatment residuals are by-products of the drinking water treatment industry. They are generally used to flocculate and settle out nutrients such as P, chemical impurities and debris from raw waters that are treated for domestic use. They generally consist of compounds containing either aluminum (Al), calcium (Ca), iron or (Fe), three elements which have the capacity to bind and retain P. It is thus of merit that WTRs be evaluated to see if they can be as beneficial agriculturally as they are in the drinking water treatment industry.Thus, the objectives of this study were to evaluate: 1) the P leaching characteristics of two coarse textured soils with low P retention capacity using three P sources (dairy effluent, poultry litter, and triple superphosphate fertilizer)and, 2) the effectiveness of a water treatment residual (WTR) for reducing the leaching of P from the soils treated with the various treatments above.

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CHAPTER 2 LITERATURE REVIEW Phosphorus (P) is an ubiquitous element being found almost everywhere on the planet. It forms approximately 0.1% of the rocks that make up the bulk of the earths crust, most of which occur in species of phosphorus-rich minerals called the apatite group Ca 5 (PO 4 CO 3 ) 3 (F, Cl, OH), the most common of which is fluorapatite Ca 5 (PO 4 ) 3 F (McKelvey, 1973). As the eleventh most abundant element on earth (McKelvey, 1973), P plays a very important role in the metabolic functions of all living organisms. It is an essential component of nucleic acids and many intermediary metabolites such as sugar phosphates and adenosine phosphates, which are an integral part of the metabolism of all life forms (Correll, 1998). The major energy storage and transfer mechanisms in all living things is dependent on the breakdown of the ester linkages of adenosine diphosphate (ADP) and adenosine triphosphate (ATP), while storage and transfer of coded genetic information involves nucleic acids which are diesters of phosphoric acid (Goldwhite,1981). Despite the widespread presence of P in the earth, only a fractional percentage of the total P in the lithosphere is concentrated in deposits consisting mainly of phosphate minerals (McKelvey, 1973). It must therefore often be added to soil to provide adequate amounts for plant growth. The commercial production of inorganic chemical phosphorus fertilizers which are applied to crops has been the conventional way of supplying the P needs of agricultural crops. There has been a notion that these chemical fertilizers in general are more likely to 4

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5 have detrimental effects on soil and water quality, and this has lead to some promotion of the use of so called natural sources of nutrients such as manures, to fertilize crops (Emeades, 2003). However, amending the soil with both, P-containing fertilizers and animal manures has increased the risk for P loss from the land and subsequent transport to rivers and lakes. In the United States, areas of intensive agricultural operations are major potential non-point sources of pollution of water bodies by eutrophication. Eutrophication as defined by Perzynski et al., (2000), is an increase in the fertility status of natural waters that causes accelerated growth of algae or plant material. The nutrients nitrogen (N) and P are often associated with eutrophication. Phosphorus is most often the element limiting accelerated eutrophication. This is because most blue-green algae are able to utilize N from the atmosphere (Pote et al., 1996). Although the total amount of P loaded to surface runoff and stream flow is important to water quality, the forms or fractions of P in soils that are released into the waters are probably more critical (Zhang et al., 2002). Numerous attempts have been made to define and identify environmentally available (labile) fractions in soils. In aquatic systems, P only occurs in pentavalent forms such as orthophosphate, pyrophosphate, longer-chain polyphosphates, organic phosphate esters and phosphodiesters, and organic phosphonates (Correll, 1998). Orthophosphate is the only pentavalent form of P which can be assimilated by bacteria, algae and plants. Phosphorus entering receiving waters is a complex of these pentavalent forms as dissolved and particulate inputs. The particulates may release phosphorus compounds to solution which may be chemically or enzymatically hydrolized to orthophosphate (Correll, 1998).

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6 Dissolved P is comprised mostly of orthophosphate, which is immediately available for algal uptake (Sharpley et al., 1994). Existing agronomic guidelines may not be appropriate for water quality protection. Agronomic soil test interpretations are based on the expected response of a crop to P, and cannot be directly translated to estimates of environmental risk (Sharpley et al., 2001). In this document, environmentally labile P will refer to P considered to be directly or potentially algae-available. The Soil Science Society of America Glossary of Soil Science Terms (2003) defines the labile pool of P as that portion which is readily solubilized or exchanged when the soil is equilibrated with a salt solution and the available pool as the amount of soil P in chemical forms accessible to plant roots or compounds likely to be convertible to such forms during the growing season. A modification of this definition for the purposes of this review will consider the labile P pool to be the soil fractions which are readily solubilized in a salt solution or water and those fractions fixed to the solid surfaces which may solubilize when exposed to a solution of low P concentration. The inclusion of these potentially soluble fractions is necessary because, with the addition of water (rainfall, groundwater etc.) to soils, the soil solution P concentration changes, and a new equilibrium is established between the soil, and the soil solution phases. This results in adsorption-desorption reactions taking place whereby P, especially water-soluble forms that are attached to particle surfaces will be readily released to the soil solution (Zhang et al., 2003), until equilibrium is reached. This equilibrium where a solution P concentration is reached such that no further adsorption or desorption takes place is called the equilibrium P concentration or EPC 0 A dilute solution of 0.01 M

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7 calcium chloride can be used to extract P that is a measure of the available soil P (Kuo, 1996). There is no standard soil extraction technique to identify the labile P fractions. There have been variations in the interpretations of labile P fractions. Nair et al. (1995) defined 1M NH 4 Cl as representing the labile P in a modified version of the Hieltjes and Lijklema (1980) fractionation scheme. Soil P fractionation is a technique which uses a series of chemical extractants to sequentially remove various chemical P forms. Mild chemical extractants are used to remove the labile fractions followed by increasingly harsher extractants which remove less labile P fractions. Pote et al. (1996) found distilled water (DI), ammonium oxalate and Fe oxide paper strips were effective at approximating P available to growing algae while Koopmans et al. (2001) noted that DI and CaCl 2 extractable P represent the more labile forms of P in soil. Other authors include potassium chloride (1N KCl) and or sodium bicarbonate (0.5M NaHCO 3 ) extractible inorganic phosphorus (P i ) in this labile fraction (Reddy et al., 1998; Sharpley, 1996). Hedley et al. (1982) used the NaHCO 3 extractable P fraction to represent labile P i and organic phosphorus (P o ) sorbed to soil surfaces. Robinson and Sharpley (1996) referred to this soil P fraction in acid to neutral soils as a reversible P fraction. Zhang et al. (2002) found that the sum of the NaHCO 3 P i and P o fractions in sandy Florida soils was a good indicator of soil potential to release labile P. He et al. (2003) also found that NaHCO 3 was a mild extractant only responsible for the removal of P physically attached to soil surfaces. As noted above, various soil test methods, fractionation procedures and mechanistic approaches have been used to estimate labile soil P. However, the

PAGE 19

8 complexity of the chemistry and mineralogy of soil makes P availability a continuum. Thus, unequivocal identification of labile compounds or fractions is difficult (Guo and Yost, 1998). However, the sequential procedure introduced by (Hedley et al., 1982) has often been used to fractionate soil P. Increasingly harsh extractants remove P fractions that are increasingly less labile. Slight modifications are sometimes made to the original procedure as is the case in this study. The fractionation extractants/steps and their associated P fractions are CaCl 2 (water soluble P i ), NaHCO 3 (P i and P o mainly sorbed to soil surfaces and considered labile), NaOH (less labile Al and Fe bound P i and P o ), HCl (unavailable Ca and magnesium (Mg) bound P i ), and residual P (unavailable or recalcitrant P o ). Water soluble P along with NaHCO 3 P i and P o will be considered as the labile soil fractions in this study. Phosphorus is supplied to field crops as inorganic fertilizers or organic materials such as manures. Many manure management recommendations are based on fertilizer response (Sharpley and Sisak, 1997) but P availability and appropriate application rates may differ between sources. The P content of manures must not be overlooked because as much as 70% of P in feed ingested by animals in intensive livestock operations is excreted (Sharpley et al., 2001). The availability of P, however, is not dependent on the total amounts of added P, but rather upon the characteristics of the P source applied to the soil (Ebeling et al., 2003). Along with understanding the constituents of manures, it is also important to know how manures affect the soil constituents (Nair et al., 2003). In developing manure management guidelines that are both agronomically and environmentally sound, the fate of manure P should be considered (Robinson and Sharpley, 1996). Several authors have pointed out that there are different effects on soil P

PAGE 20

9 pools with the use of fertilizers versus manures (Campbell et al., 1986; Ohalloran et al., 1987; Reddy et al., 1999; Sentran and Ndayegamiye, 1995). The pools of soil P and their relative distributions are important because they may be responsible in controlling the extent of P leaching (Zhang et al., 2003). Phosphorus transformations in soils involve complex mineralogical, chemical and biological processes (Zheng et al., 2002) and are dependent on a number of interactions such as inherent soil properties, P removal by crops, climatic conditions (Reddy et al., 1999) and P source characteristics. In the literature, the documented effects of the various types of added fertilizers and manures, on soil P pools and availability have varied based on at least one or a combination of the above mentioned interactions. The composition of manures vary, but P i present in animal manure types is generally high and range from 60 to 90% (Barnett, 1994a; Sharpley and Moyer, 2000). The amount and forms of P excreted depend on a number of factors such as the physiological state of the animal, the dietary levels and the feed source (Barnett, 1994b). Poultry are monogastric and require additional inorganic P to supplement their diets (Tarkalson and Mikkelsen, 2003). This results in poultry manure having higher P i contents. In a study with three different manure types, Nair et al. (2003) found that dairy manures leached the least amount of labile P while beef cattle manure leached the greatest amount despite the total P (TP) amounts being in the reverse order. Ebeling et al. (2003) also found that manures of dairy cows without supplemental inorganic P have less potential for contributing P in runoff when land applied. Sharpley and Moyer (2000), in a study using four manures and two composts, found a P i range in samples from 63 to 92%. In that same study, the water-soluble and

PAGE 21

10 NaHCO 3 P ranged from16 to 63% and 11 to 39% respectively. Dou et al. (2000) reported results with water-soluble and NaHCO 3 P fractions of, 70 and 14% and 49 and 19%, respectively, for dairy and poultry manures. This means that manures, like fertilizers, may have the potential to contribute high amounts of P to the labile and moderately labile soil P pools. Sentran and Ndayegamiye (1995) found that both manure and fertilizer applications to a silt loam increased labile and moderately labile P i Sharpley et al. (1984) also found that cattle feedlot waste increased all forms of P i in the soils to which they were applied. In another study by Sharpley (1996), using Fe-oxide strips to extract labile P from a range of agricultural soils with previous manure applications, each a different type, found that most of the Fe-oxide strip P after 15 successive extractions was from the NaHCO 3 P i soil fraction. Reddy et al. (1999) found manure application to increase all soil P pools except HCl-extractable P. Other studies have found similar significant increases in some or all pools of soil P i in particular labile and moderately labile pools. These increases in P i pools in soils may be because of the high P i contents of the manures (Sharpley et al., 1984), decreased soil P sorption because of manure addition (Reddy et al., 1999), or conversion of soil P o fractions to P i fractions induced by mineralization from increased microbial activity (Sentran and Ndayegamiye, 1995). Nair et al. (1995) also pointed out another important effect that dairy manure applications have on the soil P forms. They found that the A horizons of several soils which had dairy applications were dominated by Ca and Mg associated P which were in somewhat unstable associations. The susceptibility of the Ca and Mg associated P in these soils to constant and easy removal when subjected to leaching was also noted. Repeated extractions of the soil with 1M NH 4 Cl showed constant removal of P and a

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11 corresponding decline in the HCl soil P pool which in most soils is usually considered to be one of the most resistant pools. The efficiency of uptake by crops of applied P for fertilization is often low and rarely exceeds 20% of applied P in the year of application (Reddy et al., 1999). Soils of crop fields in intensive animal operations that are over-fertilized with P from manure relative to crop requirements (Carefoot and Whalen, 2003) will in the short-term run the risk of having high levels of labile P fractions which may be potential pollutants. This was noted in a study by Dormaar and Chang (1995) where high levels (15 and 46%) of labile P were observed in plots fertilized by manures. There is, however, the explanation that the P i fractions from P added in excess of crop uptake is readsorbed onto soil components (Hedley et al., 1982; Reddy et al., 1999). This is however dependent on the loading status and capacity of the particular soil and the timing of the application with regard to rainfall events. The climatic conditions of a region may also affect the fractions of P in a soil. Dou et al. (2002), mentioned the potential pollution threat that easily soluble P forms in manure applied to fields could pose if dissolved in rainwater. In a simulated rainfall study Sharpley and Moyer (2000) leached between 15and 58% of the total P applied using six different P sources (dairy manure, dairy compost, poultry manure, poultry litter, poultry compost and swine slurry) of which dairy manure leached the highest amount. In soils where leaching of bases and carbonates occurs, there is an increase in Al and Fe activity (Zheng et al., 2002) which may transform labile sources of P i and P o to less labile P i Griffin et al. (2003) noted that labile P pools when applied to sandy loam soils, were sorbed rapidly onto soil Al and Fe when manures were applied. The latter soil however

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12 had high Mehlich-3 Al and Fe values. In the same study, the effect of wet-dry cycles on P pools was seen in twoto threefold increases of CaCl 2 extractable P for soils with manures added. Pote et al. (1999) also noted levels of runoff P in soils subjected to wet-dry cycles varied seasonally. The inherent properties of a soil also influence the pools of soil P which will exist when manures and fertilizers are applied to agricultural lands. Zheng et al. (2002) pointed to work done by Beck and Sanchez (1994) on a previously unfertilized soil. On addition of fertilizer to this soil the NaOH P i fraction acted as a sink for fertilizer P. McKenzie et al. (1992) found NaHCO 3 and NaOH pools in an unlimed fertilized acid soil to be higher than similar limed (pH 1.1-1.5 units higher) plot. The texture of soils (clay and carbon contents) also influences the forms and amounts of P that are available (Griffin et al., 2003; Sharpley and Sisak, 1997) when manures are added. Sandy soils generally retain less P than finer-textured soils because of a deficiency of Al and Fe oxides, clay and organic matter. It is generally believed that significantly large amounts of P will not leach through soils with high amounts of clay because the P will be adsorbed onto the Al and Fe hydroxides and oxides (Cox et al., 2000; Rajan et al., 1974). However the pore size of the soil type can be very important in determining the effectiveness of even clay rich soils in retarding P movement. Cox et al. (2000) pointed to previous work in which P mobility was observed in clay, Fe and Al rich soils with macropores. Phosphorus sorption capacity is clearly the most important factor controlling the leaching potential of P from soils. The partitioning of P between the soil solution and solid phases and P release in a soil, is controlled by the sorption capacity (Zhang et al., 2003). The importance of the P application history on whether soils even retain P forms

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13 was highlighted by Holford et al. (1997). They found that, the application of manures to a soil with very little P application history had no effect on its sorption capacity. Phosphate sorption is dependent on a number of factors such as temperature, pH, soil solution concentration, aeration and time. The P application history of a piece of land to which further application of P is taking place has to be considered when assessing the sorption capacity of a soil. This is because the effective sorption capacity of these soils may change from that of the soil in its initial pre-fertilization stage. The time factor is of great importance in considering the effect of fertilization on soils with long fertilization histories. Generally it is accepted that the kinetics of P adsorption involves an initially rapid reaction lasting usually a few hours, followed by a second reaction at a much slower rate. The first reaction is believed to involve physical sorption onto the soil surfaces while the second involves chemisorption where P diffuses into the structurally porous soil particles (Barrow et al., 1998). The saturation of soil P sorption sites is a generally accepted mechanism in explaining the decrease in sorption of previously fertilized soils (with manure or fertilizer). Sharpley (1996) found that the rates and quantities of P released in his experiment were a function of soil P sorption saturation. This however, may not be the only mechanism or even the major mechanism in all cases. Diffusive penetration into variable charge surfaces may change the electrical potential of the surfaces making them more negative, thus enhancing desorption and reducing sorption of P (Barrow, 1999), possibly before the saturation of soil sorption sites. Phosphorus sources applied to soils then are able to reduce the effective P sorption capacity of a soil in subsequent P applications (Barrow et al., 1998). The continuous reaction of applied P with soil

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14 particles decreases the sorption capacity of soils with subsequent new additions of P has also been shown on sandy soils in Australia (Barrow et al., 1998). Sandy soils in comparison to fine-textured soils are very vulnerable to the leaching of P as a result of their generally low sorption capacity and macroporous nature. The most effective way to manage P mobility in these soils is, either to reduce the P loading or to increase the P sorption capacity. Currently the most feasible environmental and economic solution to this problem is the application of solid phase materials containing Al, Ca and Fe to lands with high rates of constant P loading. Various soil amendments have been and are being used to increase the P sorption capacity of soils (Gallimore et al., 1999; Haustein et al., 2000; O'Connor et al., 2002; Peters and Basta, 1996; Summers et al., 1993). These amendments are normally high in Al, Ca or Fe containing materials and residues which are usually by-products of various industries, some major ones being, the coal mining industry, the bauxite mining industry, the steel processing industry and the water treatment industry. The amendment used is sometimes dependent on its availability and economic feasibility for land application. However, there are problems with some of these amendments. Whereas some may be of low cost or even cost free and easily transported to agricultural land, they may not be environmentally beneficial. These industrial waste or by-products may contain very high levels of dangerous and toxic metals and compounds which may be detrimental to plants, animals and even humans. Bauxite red mud, a waste product of the bauxite mining/alumina industry is classified as a hazardous material. It contains large amounts of lye, soluble sodium (Na), aluminate and is highly corrosive (Peters and Basta, 1996).

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15 Materials generated from the water treatment industry will most likely have a very high capacity to immobilize soluble P and are currently being evaluated for their potential as soil amendments. Biosolids and water treatment residuals (WTRs) are the two main by-products from the water treatment industry. Work has been done with biosolids and they have been proven to be effective soil amendments, while work on WTRs is still in its somewhat early stages (Ippolito et al., 2002). Biosolids are classified as by-products of wastewater treatment plants, whereas WTRs are a waste product of drinking water treatment (Ippolito et al., 2002). Water treatment residuals are typically derived from the processes of coagulation, flocculation and sedimentation used in drinking water treatment. The treatment process involves the use of metal salts such as alum [Al 2 (SO 4 ) 3 .14H 2 O], and ferric chloride (FeCl 3 ) to form complexes with colloidal particles suspended in water thus forming aggregates and settling them out at the bottom of the source water (Butkus et al., 1998). Another type of WTR, Ca-WTR is a by-product of the water softening industry where Ca is used to remove water hardness by precipitation as insoluble Ca salts (O'Connor et al., 2002). The composition of these residuals varies among water treatment plants depending on the processes and chemicals used and also the composition of the source water being treated. The purity of coagulants used also affects the residual quality. Elliott et al. (1990) noted in a study that fractionation analysis of [Al 2 (SO 4 ) 3 .14H 2 O] and FeCl 3 sludges, found mean concentrations of all trace metals analyzed excepting Cd to be higher in the FeCl 3 sludge. This was noted to be probably attributable to the fact that the FeCl 3 sludge used by that treatment plant was a by-product of the steel industry. Most WTRs will contain some fraction of either naturally occurring colloidal/particulate matter (clay, silt

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16 etc.), insoluble metal oxide/hydroxide precipitates [e.g., Al(OH) 3 Fe(OH) 3 ] or some activated carbon (ASCE, AWWA and EPA, 1996). Water treatment residuals generally have tremendous capacity to adsorb significant amounts of P because they are treated with [Al 2 (SO 4 ) 3 .14H 2 O] (Ippolito et al., 2003). Alum hydrosolids not only reduce soluble P but they also have the added properties of improving the physical properties and water holding capacity of plant growth media (Peters and Basta, 1996). Water treatment residuals may be acceptable for use because they do not have concentrated levels of toxic organics and pathogens (Elliott et al., 1990). They also generally have lower concentrations of toxic metals such as Cd than biosolids, which at times may be derived from effluents from industrial sources (Elliott et al., 1990; Ippolito et al., 2002). Elliott et al. (1990) found the range in Cd and Zinc (Zn) contents of water treatment sludges to be 10 and 35 percent respectively of the typical corresponding mean values of municipal biosolids being land applied. O'Connor et al. (2002) also analyzed Al, Ca and Fe WTRs and found that the concentrations of the heavy metals Cd, Copper (Cu), Chromium (Cr), Nickel (Ni), Lead (Pb) and Zn were all much lower than allowable levels by federal law. Sandy Florida soils are typically acid, coarse textured and low in Ca with very little clay (Anderson et al., 1995), with Al and Fe hydroxides being the solid phase components responsible for the specific sorption of P (Lu and O'Connor, 2001). The amorphous hydroxides contained in WTRs may be of benefit to such coarse textured soils by increasing their cation exchange capacity (CEC), (Ippolito et al., 2003). Although alum WTR may appear suitable for these soils it should be noted that they have the potential to bind P very strongly and this may result in a decrease in the quantity of plant

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17 available phosphorus (Butkus et al., 1998; Ippolito et al., 2003). The potential problem of Al toxicity to plants and excess soil acidity also exists with Al WTR use. Untreated Al 2 (SO 4 ) is a very soluble salt that releases toxic Al and produces acidity when dissolved in water (Peters and Basta, 1996). Ann et al. (2000) suggested that the application of a combination of alum and Ca based biosolids to soils with low pH buffering capacity, could be very effective in soils that are subject to anaerobic environments. This is necessary because, under the low pH conditions that may be created when Al is applied to soils it is possible for the reduction of Fe 3+ to Fe 2+ releasing orthophosphate ions from iron phosphate compounds. The simultaneous application of Al and Ca based biosolids may have additional benefit as noted by Heil and Barbarick (1989), who suggested that if acidic water treatment sludges were being applied to acidic soils, then they should be limed to minimize the availability of toxic trace metals such as cadmium (Cd). Callahan et al. (2002) noted that P in soils is generally most soluble at pH values within the range of 6.0 and 7.0 so it would be ideal to have pH values outside that range to make P more insoluble. On the higher end of the above-mentioned range, P is immobilized by the precipitation of soluble calcium phosphates. Boruvka and Rechcigl (2003) referred to work of previous authors who documented very little effect of Ca based amendments on soil P retention because of the creation of induced soil negative charge and dissolution of soil Fe and Al phosphates. Consideration should therefore be given to the thought that the liming of soils containing Al and Fe phosphates may very well be expected to increase phosphate solubility (Boruvka and Rechcigl, 2003). The application of lime or some additional form of Ca based amendment may not be necessary on the farms of animal operations in Florida which have sprayfields or other

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18 forms of land application of animal manures. Animal manures are potential sources of reducing soil acidity (O'Hallorans et al., 1997; Whalen et al., 2000; Wong et al., 1998) and this pH buffering effect may last for a number of years. The short-term effects of cattle manure additions on soil pH were observed in a study conducted by Whalen et al. (2000) who observed an immediate increase of soil pH on addition of manures to soils without any additional change in soil CEC. In that study, they found higher levels of bicarbonate in the manure amended soils than in the unamended soils and concluded that the bicarbonate contributed to the pH buffering capacity of the amended soils. However, there was no evidence to support the idea that CaCO 3 added to the diets of the animals was responsible for this buffering capacity. In light of the above information, it may be worth considering pre-incorporation of Al WTRs with some forms of animal manures before application on land. The use of alum treated poultry litter has been mentioned in the literature (Moore et al., 1995; Peters and Basta, 1996). This incorporation has the added advantage of ensuring that any soluble unreacted Al salts that may be contained in these residuals may be given a chance to fully react, reducing the risk of creating soil acidity. Soils located near barns and feedlots are sometimes high in Ca. This is because limerock (Ca CO 3 ) is often used to raise the foundations of these areas. The resulting pH of these soils is generally high (>7.0) (Anderson et al., 1995; Ward et al., 1978) and the retention of P is related more to the dominance of Ca in the system rather than Al and Fe (Anderson et al., 1995; Cogger and Duxbury, 1984). It is generally thought that in these high Ca soil systems, Ca compounds are the major components likely to control the immobility of P (Ann et al., 2000; Lu and O'Connor, 2001) because at neutral pHs and

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19 higher, Ca reacts with soluble P to form Ca-phosphates (Codling et al., 2002). Based on the above mentioned information it would then follow that calcium-based boisolids (Lu and O'Connor, 2001), or alternative calcium-based soil amendments are likely to be the most effective in increasing the P retention capacity of soils around the barns and milking parlors of these Florida animal operations. Soils in pastures or hay fields away from the barns and feedlots are typically under low pH conditions with soluble Al and Fe being more likely in controlling P retention than Ca. However, there is some evidence that suggests a contrary explanation about the role Ca plays in the immobilization of P in some high pH soil systems with high Ca levels. The origination and form of the soil Ca source affects whether or not it controls P immobility. Nair et al. (1995) in their work found that labile P leached from cattle manures showed a positive relation primarily to the Ca and Magnesium (Mg) contents in solution of the manures. This meant that though there were high P concentrations in the soils they were highly unstable and suceptible to leaching. Cooperband and Good (2002) supported the previously mentioned findings in their work which showed that while calcium and magnesium phosphate minerals controlled P solubility in a poultry treated soil, this was not the case in the dairy manure treated soil.

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CHAPTER 3 MATERIALS AND METHODS Soils The soils used in the study were obtained from of two dairy animal operations, Byrd Dairy (BD) and Oak Grove Dairy (OG) farms located in the Suwannee River Basin in Suwannee County in North Central Florida. The soils have been used in the recent past for the production of hay. Their nutrient status was however quite different as a result of different fertilizer management histories. The OG hayfield had been previously fertilized with dairy manure in the form of effluent and commercial inorganic fertilizers for a number of years (approximately 10 to 15 years). The records of the quantities of effluent applied to this farm could not be obtained, however, it was considered to be a heavily manure-impacted soil. The soil at the BD hayfield received no applications of animal manures prior to collection of samples. Fertilizer was applied to this field following recommended practices for hay production. This was considered to be a relatively manure-unimpacted soil. Collection of bulk soil samples from the two locations was done by using a shovel to remove clean cuts of soil from the Ap horizons to a depth of approximately 15 cm. The soil samples were collected and placed into labeled drums. Soil from the roots of remaining vegetation was gently shaken into the respective drums and the vegetation was discarded. Three different collection points in each field were used for sample collection, and the soil was then composited into a single sample. 20

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21 All samples were brought to the laboratory and stored in a shed at room temperature. They were placed on two cleaned pieces of plastic tarpaulin wraps and placed in a greenhouse to air dry for two weeks. The air dried samples from the respective locations were then manually screened by passing them through a sieve with 2 mm openings. After this was complete, samples were homogenized manually by separately pouring out the screened contents of each drum on cleaned plastic tarpaulins and mixing the contents thoroughly with a shovel. Screened homogenized soils were then placed into their respective containers, sealed tightly and stored at room temperature for later use. Column Leaching Study A laboratory column leaching study was conducted using a simple factorial experimental design. The factors being the two soils mentioned above, three different P sources (dairy storage pond effluent, broiler litter compost, triple superphosphate fertilizer) and a control and two amendment tretaments (aluminum water treatment residual (Al WTR) and a control). This block was again repeated four times. The following combinations of 2 soils x 4 sources x 2 amendments x 4 replications gave a total of 64 leaching columns. Fractionation studies were performed on soil columns at the end of the leaching study. Column Setup The columns were built using 7.5 cm ID PVC piping cut at 30 cm lengths (Figure 3.1). Each column had end caps on the bottom which were drilled, threaded and fitted with spouts for proper drainage and collection of leachate. Pieces of woven polypropylene sheets firmly placed at the end of each column before attachment of the caps to reduce the loss of soil colloids with leaching. Soil columns were packed by

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22 pouring and lightly compacting to a depth of 25 cm (leaving a 5 cm clearance for simulated rainwater addition the soils). The P sources and amendments were applied and thoroughly incorporated into the top 4 cm of the soil column (Figure 3-1). This depth (4 cm) was chosen to allow for a 1 cm buffer in anticipation of downward movement of treatments, since the top 5 cm of each soil column was analyzed for P forms at the end of the study. Columns were placed upright in wooden racks for the duration of the study. Columns were leached nineteen times at approximately weekly intervals over a six month period with artificial rainwater (adjusted to a pH of 5 similar to that of Florida rainfall) as used by Wang et al. (1995) (Table 3-1). One pore volume (250 mL) of rainfall was used to leach each column for each of the nineteen leaching events. The application of one pore volume of rainfall to each column allowed for the collection of the desired adequate volume of leachate needed for the various leachate analyses to be performed. Columns were allowed to drain freely overnight after each leaching. Most of the rainfall applied was leached from the columns and collected in 250 cm 3 Nalgene bottles placed at the drainage spouts below each column. The contents were then analyzed for a number of variables. Table 3-1. Chemical components of simulated rainwater Chemical Formula Concentration ------mg L -1 ------MgCl 2 .6H 2 O 2.35 CaCl 2 .H 2 O 3.84 KCl 0.9 NaHCO 3 2.09 NH 4 NO 3 4.3

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23 Phosphorus sources were applied to the upper 4 cm of soil at a blanket application rate equivalent to 40 kilograms P per hectare (40 kg P ha -1 ). This rate was chosen because it is a typical application rate used by commercial farmers. The Al WTR was applied at a rate of 5% dry weight basis per gram of soil in the top 4 cm of soil (approximately 56 tons ha -1 for an A horizon). The soil was moistened before being placed in the columns to avoid any effects of hydrophobicity and preferential or disturbed flow during leaching. This was done by applying approximately 12% (66 mL) of the total pore volume (volume occupied by air and water) of DI water to a fixed mass of soil estimated to give a 25 cm soil column. Soils were kept in polyethelene Ziploc TM bags, mixed and allowed to equilibrate 24 hours. The poultry litter used in the study was obtained from the Black Hen poultry litter composting facility in Oxford, Florida. The triple superphosphate fertilizer used in the study was a commercially acquired pelletized fertilizer. The dairy storage pond effluent was obtained from the North Florida Holstein Dairy operation in Florida. The stored effluent contents of a manure storage pond were agitated and the pump used to pump the effluent out to the spray-field was used to deliver a homogenous sample into black plastic bags. Collected samples were cooled in ice chests until they arrived at the laboratory where they were stored in a refrigerator at 4 o C in a walk-in cooler until used. Well mixed homogenous samples were analyzed for total P concentrations. Because of the low concentration of solids in the dairy effluent, the required P concentration per column needed a large effluent volume. The calculated volume (636 mL) required for each

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24 Figure 3-1. Diagram of leaching column containing soil and treatment

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25 column was applied in small increments (60 mL each) to clean, labeled plastic weighing containers containing the mass of soil (250 g) estimated to represent the top 4 cm of the soil columns. The soil was air-dried before adding subsequent increments. This was done until the total calculated dairy effluent volume per column required was applied. Analytical Procedures Soil Analysis Total carbon (TC) and total nitrogen (TN) contents of the soils were determined by combustion at 1010 o C in a Carlo Erba NA-1500 CNS Analyzer (Carlo-Erba Instruments, Rodano Milan, Italy). The pH was measured on the supernatant of 1:2 soil to solution ratio that was stirred and allowed to sit for 30 minutes using an Orion pH electrode (Orion Research Inc. Boston, MA). Mehlich-1 extractable Al, Ca, Fe, Mg and P were determined on air-dried samples using a 1:4 soil to DA (0.0125 M H 2 SO4 and 0.05 M HCl) ratio shaken for 5 minutes (Mehlich 1953). Water soluble P (WSP) was determined by analyzing the extracts obtained from samples by shaking a 1:10 soil (g) water (cm 3 ) combination for one hour and then filtering contents through 0.45m filter paper. The filtrate was analyzed for P using EPA Method 365.1 (USEPA 1993). P Source/ Amendment Analysis Total phosphorus concentration determinations were made for all P sources. Homogenous samples of poultry litter weighing 0.4 g and of TSP weighing 0.09 g were digested in Kjeldahl Reagent using a modified method of Jones et al. (1991). The resulting digests were analyzed for P using EPA Method 365.1 (USEPA 1993). Homogenous samples of the liquid dairy storage pond effluent were digested in Kjeldahl reagent using a 5:1 sample to reagent ratio according to EPA Method 365.1 (USEPA 1993).

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26 Leachate Analysis Leachates samples were analyzed for pH, electrical conductivity (EC), soluble reactive phosphorus (SRP) and TP. Total phosphorus was determined using EPA Method 365.1 (USEPA 1993). Electrical conductivity and pH were measured on the same day of leachate collection. An Orion pH electrode (Orion Research Inc. Boston, MA) was used to measure pH. The measured pH values of the leachates collected during the study were converted to anti-logarithmic values (hydronium ion (H + ) concentrations) before being statistically analyzed. Water Treatment Residual Analysis Analysis and characterization of the Al WTR used in the study was done by OConnor and Elliot (2000). Soil Fractionation Fractionation of the soil samples taken at different depth increments was performed according to a modified version of the procedure used by Hedley et al. (1982). Soil columns were carefully removed and split into three depth increments (0-5 cm, 5-15 cm and 15-25 cm) from the top, respectively. A flow chart summarizing the fractionation scheme is shown in Figure 3-2. A 1:50 soil to solution ratio (0.5 g soil + 25mL of 0.01 M CaCl 2 0.5 M NaHCO 3 0.1M NaOH, and 1.0 M HCl respectively) was used for all extractions. Air-dried 0.5 g samples of soil from each depth increment (0-5cm, 5-15 cm, 15-25 cm) of the selected soil columns were used for extraction in the fractionation study. Extractants were applied to samples and shaken for 16 hours, after which the supernatant removed and centrifuged at 10,000 g for

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27 ten minutes and vacuum filtered through 0.45m filter paper. The supernatant was stored in 20 mL scintillation vials at 4 o C until analyses were performed for P i The 0.5 M NaHCO 3 and the 0.1M NaOH supernatants were analyzed for both P i and P o Sample preparation for P i analysis was done by adding 5 drops of ultra pure sulfuric acid (H 2 SO 4 ) to 5 mL aliquots of each extractant (on the day of analysis) and centrifuging at 8,000g for eight minutes. The acid was added to precipitate any organic matter present in the sample. The P o of the supernatants was determined by the respective differences between theTP and P i quantities of the supernatants (i.e. P o = TP P i ). The TP of the 0.5 M NaHCO 3 and the 0.1M NaOH supernatants was determined by adding 1 mL of 5M H 2 SO 4 + 0.3g potassium persulfate (K 2 S 2 O 8 ) to 5 mL aliquots of each supernatant in digestion tubes and digesting the samples. Samples were digested by placing them on a digestion block at 125-150 o C for 2-3 hours (until 0.5 mL of solution remained), then covering the digestion tubes with glass digestion tube caps and increasing the temperature to 380 o C for 3-4 hours. At the end of digestion, 10 mL of DI water was added to the cooled samples and they were vortexed to ensure complete dissolution of salts. The solutions were then stored in 20 mL scintillation vials at room temperature until they were analysed. The Residual P determination was done according to the method used by (Anderson, 1976). After removal of the supernatant of the final extractant (1.0 M HCl) from the soil samples, the remaining soil and solution were transferred to 50 mL beakers by carefully washing the container containing the soil (0.5 g) with DI water to dislodge soil particles. Samples were allowed to evaporate on a hotplate until only dry soil remained. Dried samples were ashed in 50 mL beakers at 550 C in a muffle furnace for 4

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28 to 5 hours, after which 20 ml of 6 M HCl was added to the samples which were then placed on a hot plate (Anderson, 1976). Dried samples were removed from the hotplate and 5 mL of 2.5 M HCl was added to them before the beaker contents were rinced with DI water and placed in 25 mL volumetric flasks. The contents of these flasks were analyzed for the residual P. Statistical Analyses All statistical analyses were performed using SAS analytical software package, (2001) SAS Institute Inc., Cary, NC, USA. Analyses of variance for the data obtained from the leachate and the fractionation studies were performed using a general linear model procedure (GLM). A mixed procedure repeated depth analysis was also performed on the fractionation data obtained from the three depths.

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29 5 drops H2SO4 + 5 ml sample Centrifuge at (10,000 g for 10 min.) Pstassium persulfate dig. 5 ml sample + 1 ml 11N H2SO4 + 0.3 g K2S2O8 Soil 0.5 g Soil + 25 mL 0.01 M CaCl2. Shake 16h; centrifuge 10 min. at 10,000 g; filter 0.45m. Decant supernatant into 20 mL scintillation vials. Store at 4C until anal y is. Soil + 25 mL 0.5 M NaHCO3 Shake 16h; centrifuge 10 min. at 10,000 g; filter 0.45 m. Decant supernatant into 20 mL scintillation vials. Store at 4C untilanal y sis. Soil + 25 mL 0.1 NaOH. Shake 16h; centrifuge 10 min. at 10,000 g; filter 0.45 m. Decant supernatant into 20 mL scintillation vials. Store at 4C until anal y sis. Soil + 25 mL 1 M HCl. Shake 16h; centrifuge 10 min. at 10,000 g; filter 0.45 m. Decant supernatant into 20 mL scintillation vials. Store at 4C until an al y sis. Recalcitrant P Ca/Mg bound P Al/Fe bound P Labile P Pi TP Decant remaining soil + HCl into 50 mL beakers. Using a hotplate allow solution to evaporate slowly until only dry soil remains. Ash then digest according to Anderson ( 1976 ) Figure 3-2. Schematic of the modified fractionation procedure adopted from Hedley et al. (1982).

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CHAPTER 4 RESULTS AND DISCUSSION Soil Characterization Prior to addition of treatments and amendments to the soils, the Mehlich-1 extractable Al concentrations in the Ap horizons of the two soils were not greatly different with the values being 153 mg kg -1 and 171 mg kg -1 for the Byrd Dairy (BD) and Oak Grove Dairy (OG) soils, respectively (Table 4-1). The BD soil also had Mehlich-1 Fe concentrations three times greater than the OG soil which had a concentration of 14 mg kg -1 The BD soil had a higher percentage C (1.59%) than the OG soil (0.99 %). The water soluble phosphorus concentration of the BD soil (1.32 mg kg -1 ) was considerably less than that of the OG soil (10.32 mg kg -1 ) being almost ten times lower. Given the above mentioned information about the soils and their respective management histories, it is reasonable to say that the OG soil was more likely to have a reduced P sorbing capacity and hence would be prone to leaching larger amounts of labile P than the BD soil when additional sources of P were added. Table 4-1. Selected Chemical Properties of the Ap Horizons of the Byrd Dairy and Oak Grove Dairy soils (n = 6). ---------------Mehlich-1 -------------Location pH TC TN WSP Al Ca Mg Fe ------% ---------------------------------mg kg -1 -----------------Byrd Dairy 5.74 Mean 1.59 0.09 1.32 153 351 35 45 Std.dev. 0.43 0.02 0.84 86 201 19 24 Oak Grove Dairy 6.50 Mean 0.99 0.05 10.32 171 635 69 14 Std.dev. 0.22 0.04 2.63 30 428 21 3 Total carbon (TC) and total nitrogen (TN) Water Soluble Phosphorus 30

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31 Amendment Characterization Elemental analysis of the WTR previously reported by OConnor et al. (2002) showed that it was dominated by Al (89 g kg -1 ) (Table 4-2) with approximately 80% of the total Al being in an amorphous form. The amorphous P is represented by the amount of oxalate extractable P (Table 4-3). Though the analytical results show a high level of organic matter in the WTR (24%), organic P only accounted for 3% of the total amount of P (2.8 g kg -1 ) contained in the WTR. The WTR had a high P sorbing capacity as was seen by the low phosphorus saturation index (PSI) value calculated in Table 4-3 (OConnor et al., 2002). The PSI is used as semi-quantitative measure of a soils ability to sorb P low phosphorus saturation index (OConnor et al., 2002; Schoumans, 2000). Table 4-2. Selected properties of the Al-WTR used in the study (OConnor and Elliot, 2000). Total Elemental Form C N C:N Fe Al Ca Mg P Solids OM pH -mg kg -1 ----------------g kg -1 -------------------% ----Alum 19.13 0.73 26.21 3.7 89.1 15.3 0.12 2.79 58.5 24.1 5.25 Organic Matter Table 4-3. Phosphorus fractions, oxalate extractable P, Fe, and Al and P sorbing capacity of the Al-WTR (OConnor and Elliot, 2000). Org. P Sequentially Extracted P Oxalate Extractable KCl NaOH HCl Sum M-1 P P Fe Al PSI % ---------------------------------mg kg -1 -------------------------------------3 <0.41 2315 473.7 2788 4.35 2664 1655 71,972 0.032 Organic P determined by loss on ignition Less than Method Detection Limit (0.41 mg kg -1 ) Phosphorus Saturation Index = oxalate P/oxalate Fe + Al (in moles) Leachate Characterization pH Statistical analysis of the hydronium ion (H + ) concentrations of the leachates collected from the BD soil showed that P source, amendment treatment (i.e. Al-WTR

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32 added vs no Al-WTR) and P source*amendment interaction had no significant (P =0.05) effects on the pH at the beginning of the study (Table 4-4). Table 4-4. p values for hydronium ion concentrations of the Byrd Dairy and Oak Grove soil column leachates for the 1 st leaching event. Soil P source Amendment P source Amendment Byrd Dairy 0.5840 0.2197 0.6784 Oak Grove 0.6384 0.8609 0.7571 At the initiation of the leaching process, pH values of the leachates from the BD soil were relatively low, averaging 3.9 for the amended and unamended P source treatments (Table 4-5). There were no significant (P =0.05) differences in pH values observed for the main interactions for the first set of leachates collected. Table 4-5. Average pH values of the Byrd Dairy soil column leachates for the 1 st leaching event. Treatment Amended Unamended Control 3.9 3.9 Dairy storage pond effluent 3.9 3.9 Inorganic fertilizer 3.9 3.9 Broiler litter compost 3.9 3.9 As the leaching progressed, the pH values of all leachates began to increase (Figure 4-1). At the completion of about the fourth leaching event, a trend of separation of pH values began to appear. The pH levels of the leachates collected from the columns treated with the dairy storage pond effluent began to get consistently higher than those of the other P sources for both the amended and unamended soil treatments (Figure 4-1). The statistical analysis of the H + concentrations at the end of the nineteenth leaching event for the BD soil produced a p value of 0.0221 for the amendment interaction which meant that there was a significant (P =0.05) amendment effect on the soil pH (Table 4-6).

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33 Table 4-6. p values for Hydronium ion concentrations of the Byrd Dairy and Oak Grove soil column leachates for the 19 th leaching event. Soil P source Amendment P source Amendment Byrd Dairy 0.1063 0.0221 0.2535 Oak Grove 0.7625 0.3110 0.8006 The average pH values of all treatments increased by at least 1.5 units ranging from 5.4 7.4 units. The dairy storage pond effluent column leachates were the highest with an average pH of 7.4 for both amended and unamended treatments (Table 4-7). The higher pH values of the dairy storage pond effluent treated column leachates is related to the Ca and Mg concentrations in the manures excreted by the dairy cattle. Nair et al., 1995, noted that the Ca and Mg supplements in the feed of dairy cattle results in high levels of these metals in the manure. Increased levels of these metals in soils treated with dairy storage pond effluents causes the pH of rainfall that leaches through these soils to increase. Table 4-7. Average pH values of the Byrd Dairy soil column leachates for the 19 th leaching event. Treatment Amended Unamended Control 5.4 6.3 Dairy storage pond effluent 7.4 7.4 Inorganic fertilizer 6.1 6.7 Broiler litter compost 5.6 6.7 The Al-WTR had an effect on the pH values leachates of the remaining P source treatments and the control. The WTR amended column leachates had lower pH values than the unamended column leachates (Table 4-7). The decrease in the pH values of the amended column leachates is most likely due to hydrolysis of Al compounds causing the release of H + ions. There were no significant (P =0.05) p values obtained in statistical analyses of both the first and last leaching events for OG soil (Tables 4-4 & 4-6). This means that the main

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34 (A) pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost (B) pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Figure 4-1. Trends in pH changes observed for theByrd Dairy soil. (A) Amended column leachates. (B) Unamended column leachates.

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35 interactions (P source, amendment, P source*amendment) had no effect on the overall mean pH for these events. There were no distinct trends of separation of pH values for leachates collected from amended and unamended treatments for the OG soil (Figure 4-2). At the initiation of the leaching, the average leachate pH values ranged between 7.1 and 7.2 (Table 4-8). Table 4-8. Average pH values of the Oak Grove soil column leachates for the 1 st leaching event. Treatment Amended Unamended Control 7.2 7.2 Dairy storage pond effluent 7.2 7.2 Inorganic fertilizer 7.1 7.2 Broiler litter compost 7.1 7.1 At the end of the second leaching, pH values increased, being in the region of 8.0 (Figure 4-2). These increased pH values were sustained throughout successive leaching events. At the end of the nineteenth leaching, the average pH values showed a approximately one pH unit increase over the average values of event one, ranging between 8.2 8.3 for all leachates (Table 4-9). Table 4-9. Average pH values of the Oak Grove soil column leachates for the 19 th leaching event. Treatment Amended Unamended Control 8.2 8.2 Dairy storage pond effluent 8.2 8.2 Inorganic fertilizer 8.3 8.2 Broiler litter compost 8.2 8.2 The effect of the high Ca and Mg concentrations in Dairy storage pond effluents on soil leachate pH was also evident in the trends observed for the OG soil. The fact that the leachate pH values of dairy storage pond effluent treated columns for the OG soil were not higher than other treatment values, did not mean that there was no effect of dairy storage pond effluent treatments on the

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36 (A) pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost B) pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost pH3.03.54.04.55.05.56.06.57.07.58.08.59.0 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Figure 4-2. Trends in pH changes observed for the Oak Grove soil. (A) Amended column leachates. (B) Unamended column leachates.

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37 OG soil. The high pH values for all the OG leachates were due to the previous history of land application of dairy storage pond effluent to the soil for a number of years. The soil had almost two times the concentrations of Ca and Mg contained in the BD soil (Table 4-1). This resulted in high pH values for all leachates from this soil and thus masking any effects the different chemical characteristics of the respective applied P sources would have on leachate pH values. Electrical Conductivity A sharp decrease in EC values was observed between the first and third sets of leachates collected (Figures 4-3 & 4-4). The overall EC values for the minimally manure impacted BD soil were lower than the highly impacted OG soil. At the beginning of the study, EC values for the BD soil ranged from 3225 3895 S cm -1 while those of the OG soil were in the range 3995 5263 S cm -1 At the end of the study, BD values ranged from 65 108 S cm -1 with those of OG ranging between 292 393 S cm -1 At the initiation of leaching, the EC values of the leachates collected from BD soils were high, being within the ranges of, 3413 3895 S cm -1 for the amended treatments and 3255 3788 S cm -1 for the unamended treatments. The values then gradually decreased with successive leachings until the completion of the study. The final EC values were in the ranges of 72 107 S cm -1 for the amended and 65 108 S cm -1 for the unamended treatments. The above decreasing trends in the EC values for leachates collected from the OG soil were similar to those observed in the BD soil leachates (Figures 4-3 & 4-4). The initial amended and unamended EC value ranges were 4183 5263 and 3995 4840 S cm -1 respectively. The final EC value ranges of the respective amendments were 338 350 S cm -1 and 292 353 S cm -1

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38 (A) Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost (B) Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Figure 4-3. Average electrical conductivity values for leachates collected from columns containing different P source treatments for the Byrd Dairy soil. (A) Amended column leachates. (B) Unamended column leachates.

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39 (A) Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Electrical Conductivity (S cm-1)0100020003000400050006000 1234567891011121314151617181 9 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost (B) Electrical Conductivity (S cm-1)0100020003000400050006000 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Electrical Conductivity (S cm-1)0100020003000400050006000 12345678910111213141516171819 Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Figure 4-4. Average electrical conductivity values for leachates collected from columns containing different P source treatments for the Oak Grove soil. (A) Amended column leachates. (B) Unamended column leachates.

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40 The first seven sets of leachates collected from the BD columns treated with dairy storage pond effluent had significantly (P = 0.05) higher EC values than the other leachates of the remaining P sources (Figure 4-3). This was consistent for both amended and unamended treatments. The dairy storage pond effluent treated column leachates for the OG soil, showed a similarly higher trend than the remaining leachates of the columns with different P source treatments leachates (Figure 4-4). This trend was however not observed after the third leaching event. There was no other trend of distinction of the EC values of the leachates of columns with remaining treatments. Electrical conductivity of a soil or soil solution is a measure of its total salt concentration. The general inorganic dissolved solutes that contribute to the EC of a soil are Na + Mg 2+ Ca 2+ K + Cl SO4 2, HCO3 and CO3 2(Rhoades 1993). A high EC value can therefore be interpreted as a high salt concentration and vice versa. Among the leachates, the initially higher EC values of the effluent treated leachates is because the dairy storage pond effluent contained more soluble salts than the other treatments, which were transported with the leaching solution applied to these columns. The relatively high EC values of the leachates collected from the first three leachings for both soils can be explained by a mechanism described by Jackson (1958), which causes soil drying in arid and semi arid soils and has the effect of increasing the soluble salt content at the soil surface. As water is removed by evaporation the dissolved salts are drawn out and deposited on the soil surface. The soils were air dried prior to leaching in a greenhouse and a similar process of dehydration of the soil salts occurred on evaporation of the soil moisture. Leaching of these dried soils caused the salts to re-dissolve into the leachates resulting in very high EC values for the first three sets of leachates.

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41 According to Jackson (1958), fertilization of soils may lead to a build up of excess salts in that soil. This explains why the OG soils because of their previous fertilization history, had higher EC values than the BD soil which was minimally impacted by fertilization. Among the respective treatments, the higher EC values of the dairy storage pond effluent treatments would most likely be associated with the high amounts of leachable Ca, K, Na and Mg salts typically contained in them. Phosphorus The OG soil leached significantly greater amounts of P than the BD soil among all the treatments and amendments (Table 4-10). On average, there was a five-fold difference in the overall average P leached between both soils (Figure 4-5). Previous history of the OG soil involved dairy manure application for over ten years may have contributed to this observation. The soil therefore had high background levels of labile P as noted in the control, which was most likely associated with unstable and readily leached Ca and Mg compounds contained in the manure (Nair et al., 1995). This meant that the entire soil column had high P concentrations, some of which was dissolved in the simulated rainwater used to leach the columns. There was no significant difference between the cumulative SRP and the TP in the collected the leachates obtained throughout the duration the study. This observation was evident for all P sources and amendments for the respective soils (Table 4-11). This indicated that there was not a great amount of soluble organic P leached from both soils used in the study. The Al-WTR proved to be effective at retaining soil SRP. A comparison of amended and unamended treatments of the BD soil showed that significantly (P = 0.05) less SRP was leached from the amended treatments (3.9 5.3 mg P) for each P source

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42 (A) Byrd CummulativeSRP (mg)0510152025303540 Leaching Event12345678910111213141516171819 ByrdOak Grove CummulativeSRP (mg)0510152025303540 Leaching Event12345678910111213141516171819 Byrd CummulativeSRP (mg)0510152025303540 Leaching Event12345678910111213141516171819 ByrdOak Grove CummulativeSRP (mg)0510152025303540 Leaching Event12345678910111213141516171819 (B) Byrd CummulativeTP (mg)0510152025303540 Leaching Event1234567891011121314151617181 9 ByrdOak Grove CummulativeTP (mg)0510152025303540 Leaching Event1234567891011121314151617181 9 Byrd CummulativeTP (mg)0510152025303540 Leaching Event1234567891011121314151617181 9 ByrdOak Grove CummulativeTP (mg)0510152025303540 Leaching Event1234567891011121314151617181 9 Figure 4-5. Overall average masses of phosphorus leached from the Byrd Dairy and the Oak Grove Dairy soils. (A) Soluble reactive phosphorus. (B) Total phosphorus.

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43 Table 4-10. SRP amounts leached from BD and OG soils over 19 leaching events. SRP Control Dairy Fertilizer Broiler litter compost ------------------------------------mg P ------------------------------------Am NAm Am NAm Am NAm Am NAm BD 3.90A c 4.80A b 5.30B ab 6.50A a 3.90B c 5.60A ab 4.00B c 6.00A ab OG 21.42A c 23.58A bc 20.93B c 26.24A ab 21.62B c 27.69A a 20.98B c 24.93A ab Table 4-11. TP amounts leached from BD and OG soils over 19 leaching events. TP Control Dairy Fertilizer Broiler litter compost ------------------------------------mg P ------------------------------------Am NAm Am NAm Am NAm Am NAm BD 3.85B c 5.10A c 7.39B b 9.00A a 4.21B c 6.48A b 4.22B c 6.61A b OG 22.90A c 24.67A bc 21.96B c 26.63A ab 23.03B c 29.01A a 21.84B c 26.91A ab Means within each soil followed by the same letter are not significantly different LSD =0.05 Capital letters represent differences for amended and unamended treatments for each P source Superscripted lower case letters represent differences among all treatments Amended Unamended excepting the control, were there was no difference between the amended and unamended treatments (4.8 6.5 mg P) (Table 4-10). The fact that there was no difference between the amount of P leached between the amended and unamended control treatments shows that there was no effect of addition of the WTR on increasing the SRP leached from the soils. Among the amended BD treatments, the amended dairy storage pond effluent leached a significantly greater quantity of SRP (5.30 mg P) than the other amended treatments, which were not statistically (P = 0.05) different from each other. The WTR was effective at retaining the P leached from the fertilizer and broiler litter compost litter treatments, to the same amount as the control treatment. This shows that the WTR had sufficient P retention capacity to retain the added P from the applied sources with the exception of the dairy storage pond effluents. The reduced effectiveness of the WTR at reducing the P leached from the dairy storage pond effluent treatment was most likely related to one or both of two factors 1) the P was mostly as SRP when added to the soil 2)

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44 the existence of some soluble organic carbon in the dairy storage pond effluent. The effluent was in a very liquid form containing few suspended solids. This means that the majority of the P was in a water-soluble form and, upon rewetting the soil during leaching the P may have easily been solubilized and moved vertically with the leaching solution. Among the unamended BD columns, the dairy storage pond effluent leached the greatest mass of P with the remaining treatments being in the order fertilizer > broiler litter compost litter. The fertilizer was expected to leach more SRP than the broiler litter compost because it is designed to be a source of readily available plant P. The dairy storage pond effluent was the only treatment to leach a significantly higher amount of SRP than the control treatment. This showed that the dairy storage pond effluent P was in a more leachable from. For the highly manure impacted OG soil, a comparison of the leached SRP between amended and unamended soil treatments (Table 4-10) revealed a somewhat similar trend to that of the BD soil. Among all treatments with the exception of the control soil treatments, the difference between the respective amended and unamended treatments for each P source was significant. There was no difference between the SRP leached between the amended and unamended controls. This again showed that the P content of the WTR was not being released when the soils were leached, because of the high affinity of the Al in the WTR for P and the high P sorbing capacity of the WTR. Among the amended OG treatments, the effectiveness of the WTR on the leachable P in the layer of application was once more evident (Table 4-10). Though the soil was

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45 heavily manure-impacted, an effect of the WTR on the SRP leached was observed. There was no difference in the quantity of SRP leached from the various P sources. Among the unamended treatments, SRP amounts leached from soils were in the order fertilizer > dairy storage pond effluent > broiler litter compost litter, though differences in SRP leached among these sources were not significant (P= 0.05). The fertilizer treatment was the only treatment which leached a significantly greater quantity of SRP than the control. The high levels of SRP in this soil prior to the study may have masked the effects of the differences between the amounts of SRP, which existed among applied P sources in the overall leachate P from the soil columns. Though the nutrient status of the soils used in the study was different, the addition of sources of P at a rate equivalent to 40 kg P/ha. (18mg P/column) to the soils had significant (P =0.05) effects on the SRP leached from the respective soils. This was seen in the significant differences between control and P source treatments for amended (OG) and unamended (BD and OG) soils (Table 4-10). The effect of adding P to a previously manure-impacted soil was also evident when the overall differences in leached SRP (excluding controls) from amended and unamended treatments within each soil were compared. The BD soil had an average difference of 1.6 mg P while the OG, with an average difference of 5.1 mg P, was over three times that of the BD soil. Fractionation Statistical analysis of the sequential fractionation data obtained from the BD soil showed significant p values (P = 0.05) for all main effects within at least one P fraction (Table 4-12). The HCl P fraction was the only fraction that did not have any significant p values. A closer analysis of the mean P values in Table 4-13 revealed in general no

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46 consistent trends of major differences or activity between the amended and unamended soil fractions in the 5-15 cm and the 15-25 cm depth increments in the leaching columns from top down respectively. The data for the soil samples from the 0-5 cm layer showed some differences both between amendments and also among depths, being different from the other two depths at times. This observation was consistent with the fact that the depth of incorporation of all P sources and amendments was within the top 5 cm. The sequential data from the 0-5 cm layer was hence used to analyze the effect of the WTR on soil P forms. Table 4-12. p values for main effects and interactions for the BD soil. (P = 0.05). P fraction Depth P source Amendment P source Depth LabileP <0.0001 0.0673 0.0091 <0.0001 NaOH P i <0.0001 0.0903 0.0003 <0.0001 NaOH P o 0.0007 0.6757 0.0210 0.0001 HCl P 0.2904 0.4849 0.2214 0.4300 Residual P 0.0114 0.0030 0.0038 0.0006 Sum P <0.0001 0.5869 <0.0001 0.0729 P fraction Amendment Depth P source *Amendment P source Amendment* Depth Labile P 0.0178 0.0759 <0.0001 NaOH P i <0.0001 0.0480 <0.0011 NaOH P o 0.0031 0.0058 0.0015 HCl P 0.5613 0.3700 0.4303 Residual P 0.0135 0.2540 0.0005 Sum P <0.0001 0.7757 0.0392 Sum of P fractions Labile P = (CaCl 2 P + NaOH P i + NaOH P o ) Data for the labile fraction of P (LP) for the 0-5 cm depth in the BD soil showed no significant differences (P = 0.05) between amended and unamended columns of the respective P sources except for the dairy storage pond effluent treated columns (Table 4-13). However, an increasing trend of NaOH P i in amended over unamended treatments was observed. The high binding capacity of the Al-WTR most likely was responsible for this increase in NaOH P i by providing additional surface sites for the adsorption of labile P in the soil. Though the P may have just been physically sorbed and not chemically,

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47 there was a retention effect seen. The amended dairy storage pond effluent treatment contained significantly less LP than the unamended treatments (Table 4-13). This was due to the highly leachable constituents of the effluent which may have resulted in more of the P being quickly leached below the depth of amendment with the rainfall. The NaOH P i fraction was the fraction which showed the major effect of the WTR on soil labile P. Among all P source treatments with the exception of the control, the amount of NaOH P i contained in the amended treatments was at least three times greater than the unamended treatments (Table 4-13). This shows that the Al contained in the WTR was very effective at complexing soil P, retaining it as the strongly held more resistant NaOH extractable P i fraction. The large differences between the amended and unamended NaOH P i amounts may be partly explained by the fact that LP which would normally be leached to lower soil depths during rainfall was strongly and quickly complexed by the Al oxide sites of the Al-WTR. The differences in leached LP were however too small to explain entirely the huge differences observed for the NaOH P i fraction. Another factor that may have contributed to this huge P difference may be the fact that the WTR was a by-product of a drinking water treatment plant thus contributing an additional source of P to this fraction. Additional to the conversion of the LP fraction of both soils and sources to NaOH P i the WTR may have converted the other P fractions in the added P sources to the strongly held Al and Fe bound P i fraction. The control treatments were not statistically different, though the amended treatment contained more P than the unamended. For the

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Table 4-13. Sequential data for amounts of P (g P/g soil) in the soil P fractions in the Byrd Dairy soil. Control Dairy e ffluent Fertilizer Broile r litter c om post Labile P A m NA m A m NA m A m NA m A m NA m 0-5 c m 37.5 AB a 34.1A a 33.0 A a 47.9B c 50.0 C d 44.5BC b c 47.0B b c 42.9 B b c 5-15 c m 39.1 B 41.2 BC 33.0C A 39.3AB 35.8 A 40.5AB 35.0 AB 43.3 B 15-25 c m 44.5 C 42.8BC 45.0 B 43.5 B 39.8 AB 50.0C 36.9 AB 41.8 B NaOH P i 0-5 c m 28.0A a 19.0A a 115.0 B b 34.5 A a 113.5 B b 21.0 A a 120.5 B b 28.0 A a 5-15 c m 25.0 A 28.5 A 20.0 A 18.0 A 21.5 A 16.5 A 21.5 A 19.5 A 15-25 c m 28.0 A 30.5 A 18.0 A 24.5 A 17.0 A 32.0 A 18.5 A 23.0 A NaOH Po 0-5 c m 102.5C 35.5 AB c a 43.5 A a b 47.5 A a b 50.5 A b 49.5 A a b 50.5 A b 46.0 A a b 5-15 c m 39.0 B 24.5 A 46.5 A 45.0 A 45.0 A 45.0 A 51.5 A 48.5 A 15-25 c m 39.5 B 32.5 AB 45.0 A 46.5 A 42.5 A 49.0 A 48.0 A 51.0 A HCl P 0-5 c m 3.5A a 1.5 A a 3.0 A a 2.5 A a 5.5 A a 3.0A a 4.0 A a 3.5 A a 5-15 c m 0.5 A 1.0 A 0.5 A 0.5 A 1.0 A 0.5 A 0.5 A 0.0 A 15-25 c m 18.0 B 0.5 A 0.5 A 1.0 A 0.5 A 1.0 A 0.5 A 1.0 A Residual P 0-5 c m 35.0A c 24.0A b c 11.0 A a 12.5 A a b 11.0 A a 7.0A a 15.0 A a b 9.5 A a 5-15 c m 23.0 A 22.0 A 53.5 B 12.0 A 15.5 A 2.0 A 16.0 A 13.0 A 15-25 c m 24.0 A 21.0 A 17.0 A 12.0 A 14.5 A 1.0 A 13.5 A 11.0 A Su m P 0-5 c m 206.5C b 115.5 A a 206.0 C b 145.5 B a 230.0 B b c 125.0 A a 237.0 B c 130.5 A a 5-15 c m 127.5 AB 117.0 A 154.0 B 114.5 A 119.0 A 103.5 A 124.5 A 124.5 A 15-25 c m 155.0 B 127.5 A 126.0 AB 127.0 A 115.0 A 133.5 A 118.5 A 128.0 A 48 Values with the same capital letters represent least squares means within each P source that are significant at the = 0.05 level using pooled variance comparitive estimates in an appropriate t-statistic. Values with the same lower case superscripted letters represent least squares means among means in the 0-5 cm soil column depth that are significant at the = 0.05 level using pooled variance comparitive estimates in an appropriate t-statistic. Amended Unamended

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49 NaOH soil P fraction, the amended treatments contained significantly higher amounts of P than unamended treatments. However, whereas the major differences for the treatments with added sources of P were seen in the NaOH P i fraction, the difference for the control was evident in the NaOH P o fraction. The differences in P amounts between the amended and unamended sources for the more resistant Al and Fe bound NaOH P o fraction were small and not statistically significant for all P sources except for the control where the amended treatment was more than twice the amount of that in the unamended treatments (Table 4-13). There was no effect of P source and WTR on the more resistant residual and HCl soil P fractions (Table 4-13) as the differences were between amended and unamended treatments were not significant. These fractions tend not to be easily changed and usually changes are seen over long periods of time. There was a significant difference between the sum of the P fractions in the amended and unamended soils for all P sources (Table 4-13). This means that the P retention capacity of the WTR amended soils was greatly enhanced by the use of the WTR. Statistical analysis of the sequential fractionation data obtained from the OG soil shows that there were significant interactions of the main effects (Table 4-14). The LP, NaOH P i and NaOH P o extractable P fractions were most notable with significant p values for most interactions. The interactions of the main effects for the HCl P, residual P and were not significant (P = 0.05). The amendment main effect showed a significant (P = 0.05) p value for the combined total of the P fractions (sum P) (Table 4-14).

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50 Table 4-14. p values for main effects and interactions for the OG soil (P=0.05). P fraction Depth P source Amendment P source Depth Labile P 0.0001 0.0119 <0.0001 <0.0001 NaOH P i 0.0001 <0.0001 <0.0001 <0.0001 NaOH P o <0.0001 <0.0001 0.449 <0.0001 HCl P 0.9983 0.1683 0.4231 0.1574 Residual P 0.4924 0.0042 0.4304 0.1114 Sum P 0.1880 0.3535 0.0074 0.4030 P fraction Amendment Depth P source *Amendment P source Amendment* Depth Labile P <0.0001 0.0244 0.0001 NaOH P i <0.0001 0.0002 0.0001 NaOH P o 0.0002 0.550 0.0001 HCl P 0.0305 0.1779 0.5932 Residual P 0.2195 0.0376 0.8171 Sum P 0.0058 0.1312 0.5926 Sum of P fractions Labile P = (CaCl 2 P + NaOH P i + NaOH P o ) The LP fractions in the 0-5 cm depths of the amended OG soil treatments were significantly less than the unamended ones for all sources. This means that the addition of the WTR decreased the amount of soil LP. Table 4-15 shows that there seemed to be a depth effect of LP in the columns, i.e. LP increased with depth. This observation was consistent for both amended and unamended P sources. This demonstrates the effect rainfall or leaching of P on a heavily P loaded soil with limited P fixing capacity to which labile sources of P have been added. The effects of the Al-WTR on the NaOH P i fraction were evident only in the 0-5 cm soil depths (Table 4-15). This was expected since the amendment was applied at this depth. As in the case of the BD soil, all amended P sources with the exception of the control had significantly greater amounts of NaOH P i than the unamended treatments at this depth. The largest difference of 153 g P/ g soil was observed for the fertilizer treatment which was expected to have a high amount of available P. The amended and unamended control treatments were not significantly different. This observation was similar to the control of the BD NaOH P i soil fraction.

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51 As in the case of the BD soil, only the control NaOH Po fraction showed any significant difference (121 g P/ g soil) between amended and unamended treatments. This difference of 121 g P/ g soil which was observed in the 0-5 cm depth showed the amended treatment containing over two times as much P as the unamended one (Table 4-15). The more resistant HCl and residual P fractions which generally take longer to change showed no significant trends of changes between amended and unamended treatments. This observation was evident at all depths in the OG soil as was also the case in the BD soil (Tables 4.13 & 4.15). Unlike the BD soil, the difference between the sum P extracted from the amended and unamended P fractions for OG was not significant (P = 0.05) for all P sources (Table 4-15). The dairy storage pond effluent and broiler litter compost litter treated soils showed no difference between the amended and unamended soils. This means that the WTR was not effective for these treatments in increasing the overall P retention capacity. This may be due to the Ca or organic matter contents interfering with the ability of the Al to complex or sorb the soil P. However, the WTR was effective at decreasing the percentages of labile P in the soils to which they were applied (Appendix B). The percentages of the more stable NaOH extractable Al and Fe bound soil P was also increased in the soils amended with the WTR (Appendix B). The WTR amended soils that had no P source additions had percentage increases in the soil NaOH P o fraction while those with P source additions had percentage increases in NaOH P i fraction. This is was somewhat of an anomaly which I was unable to explain.

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Table 4-15. Sequential data for amounts of P (g P/g soil) in the soil P fractions in the Oak Grove soil. Control Dairy Fertilizer Broile r litter c om post Labile P A m NAm A m NA m A m Na m A m NA m 0-5 c m 64.2 A a 82.0B b 62.2 A a 97.3 CD c 60.6 A a 92.4 B c 61.9 A a 76.7BC b 5-15 c m 87.1 B 87.7 B 86.6 B 94.2 BC 84.2 B 101.4 CD 80.3 B 89.3 CD 15-25 c m 97.9 C 105.4CD 98.5 CD 103.2D 94.5 BC 109.1D 93.8D 93.8 D NaOH P i 0-5 c m 63.0 A a 69.0 A a 193.0B c 123.0A b 272.0 C d 119.0AB b 187.5B c 132.0A b 5-15 c m 81.5 AB 82.5 AB 143.0 A 133.0 A 136.5 B 122.5AB 141.0A 140.5A 15-25 c m 93.5 B 101.5B 140.0A 140.0A 142.0 B 134.5B 145.0A 139.5A NaOH Po 0-5 c m 234.5 B d 113.5A c 67.0 A b 50.5 A a b 19.0 A a 35.5 A a 66.0 B b 44.5 AB a b 5-15 c m 103.5 A 95.0 A 46.0 A 40.5 A 37.5 A 37.0 A 46.0 A 46.5 AB 15-25 c m 88.0 A 94.5 A 41.5 A 47.0 A 47.5 AB 44.5 A 41.0 A 45.5 AB HCl P 0-5 c m 61.0 AB a 81.0 B a 61.0 A a 72.5 A a 75.5 AB a 60.0A a 55.0 A a 80.5 B a 5-15 c m 54.0 A 59.5 AB 71.0 A 71.5 A 92.0 B 69.5 AB 69.5 AB 58.5 A 15-25 c m 56.0 AB 58.5 AB 99.5 B 67.5 A 84.5 AB 61.5 A 61.5 AB 55.5 A Residual P 0-5 c m 40.5 AB b c 43.0 AB c 33.5 A b c 33.5 A b c 29.5 A B a b 26.0 A B a b 21.5 A a 31.5 A b 5-15 c m 31.5 A 40.5 AB 34.0 A 31.0 A 30.0 A B 29.0 A B 32.5 A 43.0 B 15-25 c m 42.0 AB 42.0 AB 33.0 A 32.5 A 35.0 B 21.0 A 33.5 A B 37.5 B Su m P 0-5 c m 462.5 B c 389.5 A b 417.0 A b c 376.5 A a b 456.5 C c 333.5 A a 392.5 A b 365.0 A a b 5-15 c m 357.0 A 365.0 A 380.5 A 370.0 A 380.0 AB 360.0 AB 370.0 A 377.0 A 15-25 c m 378.0 A 402.0 A 411.5 A 391.0 A 402.0 B 371.0 AB 375.0 A 372.5 A 52 Values with the same capital letters represent least squares means within each P source that are significant at the = 0.05 level using pooled variance comparitive estimates in an appropriate t-statistic. Values with the same lower case superscripted letters represent least squares means among means in the 0-5 cm soil column depth that are significant at the = 0.05 level using pooled variance comparitive estimates in an appropriate t-statistic. Amended Unamended

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CHAPTER 5 CONCLUSION This study has provided information regarding the leaching and retention of P from fertilizer and manure sources added to sandy soils. The notion that P applications to a soil can be made based on the total P content of the P source irrespective of the source characteristics is not a sound one. It was clear from the study that even in the short-term, differences in P release characteristics among different P sources will occur. As in the case of the dairy effluent used in the study, some manures may be very efficient sources of readily available P, being equally or even more effective than commercial fertilizers. If the applied source of P is in the form of a manure, the type of manure and the physical state of the manure is critical to its P release characteristics in the soil. While the diet and the physiological state of animals gives a general idea of the composition of manures, the physical characteristics play a great role. Manures which are dried and contain mixes of litter or bedding material such as wood shavings may not leach P from soils as readily in the short-term as those applied in a liquid or semi liquid form. To minimize immediate loss of P from applied manures to these soils, factors such as soil fertilization history, time of application, crop cover and crop P removal capabilities should be considered. Frossard et al. (1989) noted that soils with a history of manure applications with more organic P relative to inorganic fertilizers are more prone to leaching. Hence, even if there are management strategies in place to prevent loss of P from the surface of these soils, the soil below the surface may contribute significantly to the amount of P leached (McDowell and Sharpley, 2001). 53

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54 Aluminum WTRs have a great potential to be used agriculturally to increase the P sorption capacity of the A horizons of fields which are fertilized with manures. They are relatively inexpensive, and the major operational costs associated with the use of them by farmers may be in transporting them to the farms and operation of machinery during soil incorporation. Their heavy metal contents are generally much lower than those of biosolids, which are land applied even to fields of arable crops. However, it would be ideal to incorporate the WTRs into the soils of new manure application fields. In the case of soils where the entire soil column may be loaded with P from previous management practices, the WTRs are still useful. In the event of flooding, or in places where the water table fluctuates or is close to the soil surface, the WTR may be able to remove dissolved P from the groundwater that resurfaces from greater depths in soils. Effective P management can be done on farms where manures are land applied. This requires future work on the potential use of Al WTRs and consideration of the above mentioned factors affecting the leaching of P from the various P sources in collaboration with extension agents and soil analytical laboratories.

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APPENDIX A PHOSPHORUS CONCENTRATIONS OF FERTILIZERS AND MANURES AND THE QUANTITIES OF EACH APPLIED TO EACH SOIL COLUMN Phosphorus source Phosphorus concentrations Quantity/ column Dairy storage pond effluent 28 g mL -1 636 mL Triple superphosphate fertilizer 176,000 g g -1 0.09 g Broiler litter compost 28,000 g g -1 0.65 g 55

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APPENDIX B PERCENT CHANGES IN SOIL PHOSPHORUS FRACTIONS OBSERVED THE FOR BYRD DAIRY AND OAK GROVE SOILS 18.0%14.0%17.0%1.5%49.5%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -control treatment 0 Al-WTR amended 18.0%14.0%17.0%1.5%49.5%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -control treatment 0 Al-WTR amended 21.0%1.0%31.0%17.0%30.0%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -control treatment 0 No Al-WTR 21.0%1.0%31.0%17.0%30.0%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -control treatment 0 No Al-WTR 56

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57 5.5%1.5%21.0%56.0%16.0%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -dairy storage pond effluent treatment Al-WTR amended 5.5%1.5%21.0%56.0%16.0%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -dairy storage pond effluent treatment Al-WTR amended 9.0%1.5%32.5%24.0%33.0%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -dairy storage pond effluent treatment No Al-WTR 9.0%1.5%32.5%24.0%33.0%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -dairy storage pond effluent treatment No Al-WTR

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58 5.0%2.0%22.0%49.0%22.0%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -fertilizer treatment 0 Al-WTR amended 5.0%2.0%22.0%49.0%22.0%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -fertilizer treatment 0 Al-WTR amended 35.5%17.0%40.0%2.0%5.5%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -fertilizer treatment 0 No Al-WTR 35.5%17.0%40.0%2.0%5.5%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -fertilizer treatment 0 No Al-WTR

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59 20.0%51.0%21.0%2.0%6.0%0102030405060Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy broiler litter compost treatment Al-WTR amended 20.0%51.0%21.0%2.0%6.0%0102030405060Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy broiler litter compost treatment Al-WTR amended 33.0%22.0%35.0%3.0%7.0%0102030405060Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -broiler litter compost treatment No Al-WTR 33.0%22.0%35.0%3.0%7.0%0102030405060Labile P NaOH Pi NaOH Po HCl P Residual P Byrd Dairy -broiler litter compost treatment No Al-WTR

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60 9%13%50%13%15%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -control treatment 0 Al-WTR amended 9%13%50%13%15%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -control treatment 0 Al-WTR amended 11%20%29%17%23%05101520253035Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -control treatment No Al-WTR 11%20%29%17%23%05101520253035Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -control treatment No Al-WTR Oak Grove Dairy -control treatment No Al-WTR

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61 46%16%15%8%15%01020304050Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -dairy storage pond effluent treatment Al-WTR amended 46%16%15%8%15%01020304050Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -dairy storage pond effluent treatment Al-WTR amended 9%19%13%32%27%05101520253035Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -dairy storage pond effluent treatment No Al-WTR 9%19%13%32%27%05101520253035Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -dairy storage pond effluent treatment No Al-WTR

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62 6%16.5%4%59.5%14%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -fertilizer treatment Al-WTR amended 6%16.5%4%59.5%14%010203040506070Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -fertilizer treatment Al-WTR amended 8%18%10.5%35.5%28%010203040Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -fertilizer treatment No Al-WTR 8%18%10.5%35.5%28%010203040Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -fertilizer treatment No Al-WTROak Grove Dairy -fertilizer treatment No Al-WTR

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63 5%14%17%48%16%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -broiler litter compost treatment 0 Al-WTR amended 5%14%17%48%16%010203040506Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -broiler litter compost treatment 0 Al-WTR amendedOak Grove Dairy -broiler litter compost treatment Al-WTR amended 9%22%12%36%21%010203040Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -broiler litter compost treatment No Al-WTR 9%22%12%36%21%010203040Labile P NaOH Pi NaOH Po HCl P Residual P Oak Grove Dairy -broiler litter compost treatment No Al-WTR Oak Grove Dairy -broiler litter compost treatment No Al-WTR

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APPENDIX C PHOSPHORUS CONCENTRATIONS FOR THE BYRD DAIRY AND OAK GROVE LEACHATES Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Al-WTR amended Total phosphorus in leachates from the Byrd Dairy soil Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventTotal phosphorus in leachates from the Byrd Dairy soil No Al-WTR 64

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65 Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Concentration (g mL-1)-10123456789101112131415 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Al-WTR amended Total phosphorus in leachates from the Oak Grove Diary soil Concentration (g mL-1)-10123456789101112131415 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event12345678910111213141516171819 Concentration (g mL-1)-10123456789101112131415 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event12345678910111213141516171819 No Al-WTR Total phosphorus in leachates from the Oak Grove Dairy soil

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66 Concentration (g mL-1)01234567891011 ControlDairy storage pond effluentTriple superphosphatefertilizerRoilerlitter compost Leaching Event12345678910111213141516171819 Concentration (g mL-1)01234567891011 ControlDairy storage pond effluentTriple superphosphatefertilizerRoilerlitter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerRoilerlitter compost Leaching Event12345678910111213141516171819 Al-WTR amended Soluble reactive phosphorus in leachates from the Byrd Dairy soil Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizer Broiler litter compost Leaching Event Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizer Broiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizer Broiler litter compost Leaching Event No Al-WTR Soluble reactive phosphorus in leachates from the Byrd Dairy soil

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67 Soluble reactive phosphorus in leachates from the Oak Grove Dairy soil Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Al-WTR amended Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event Concentration (g mL-1)01234567891011 12345678910111213141516171819 ControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching EventControlDairy storage pond effluentTriple superphosphatefertilizerBroiler litter compost Leaching Event No Al-WTR Soluble reactive phosphorus in leachates from the Oak Grove Dairy soil

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LIST OF REFERENCES Anderson, J. M. 1976. An ignition method for determination of total phosphorus in lake sediments. Water Resources. 10:329-331. Anderson, D.L., O.H. Tuovinen, A. Faber, and I. Ostrokowski. 1995. Use of soil amendments to reduce soluble phosphorus in dairy soils. Ecological Engineering 5:229-246. Ann, Y., K.R. Reddy, and J.J. Delfino. 2000. Influence of chemical amendments on phosphorus immobilization in soils from a constructed wetland. Ecological Engineering 14:157-167. American Society of Civil Eengineers Manuals and Reports on Engineering Practice No.88, AWWA Technology Transfer Handbook, U.S. EPA/625/R-95/008, 1996. Management of water treatment residuals. Barnett, G.M. 1994a. Manure-P Fractionation. Bioresource Technology 49:149-155. Barnett, G.M. 1994b. Phosphorus forms in animal manure. Bioresource Technology 49:139-147. Barrow, N.J., M.D.A. Bolland, and D.G. Allen. 1998. Effect of previous additions of superphosphate on sorption of phosphate. Australian Journal of Soil Research 36:359-372. Barrow, N.J. 1999. The four laws of soil chemistry: the Leeper lecture 1998. Australian Journal of Soil Research 37:787-829. Beck, M.A., and P.A. Sanchez. 1994. Soil-phosphorus fraction dynamics during 18 Years of cultivation on a typic paleudult. Soil Science Society of America Journal 58:1424-1431. Boruvka, L., and J.E. Rechcigl. 2003. Phosphorus retention by the Ap horizon of a spodosol as influenced by calcium amendments. Soil Science 168:699-706. Butkus, M.A., D. Grasso, C.P. Schulthess, and H. Wijnja. 1998. Surface complexation modeling of phosphate adsorption by water treatment residual. Journal of Environmental Quality 27:1055-1063. 68

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69 Callahan, M.P., P.J.A. Kleinman, A.N. Sharpley, and W.L. Stout. 2002. Assessing the efficacy of alternative phosphorus sorbing soil amendments. Soil Science 167:539-547. Campbell, C.A., M. Schnitzer, J.W.B. Stewart, V.O. Biederbeck, and F. Selles. 1986. Effect of manure and P fertilizer on properties of a black chernozem in southern Saskatchewan. Canadian Journal of Soil Science 66:601-613. Carefoot, J.P., and J.K. Whalen. 2003. Phosphorus concentrations in subsurface water as influenced by cropping systems and fertilizer sources. Canadian Journal of Soil Science 83:203-212. Codling, E.E., C.L. Mulchi, and R.L. Chaney. 2002. Biomass yield and phosphorus availability to wheat grown on high phosphorus soils amended with phosphate inactivating residues. III. Fluidized bed coal combustion ash. Communications in Soil Science and Plant Analysis 33:1085-1103. Cogger, C., and J.M. Duxbury. 1984. Factors affecting phosphorus losses from cultivated organic soils. Journal of Environmental Quality 13:111-114. Cooperband, L.R., and L.W. Good. 2002. Biogenic phosphate minerals in manure: Implications for phosphorus loss to surface waters. Environmental Science & Technology 36:5075-5082. Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: A review. Journal of Environmental Quality 27:261-266. Cox, J.W., C.A. Kirkby, D.J. Chittleborough, L.J. Smythe, and N.K. Fleming. 2000. Mobility of phosphorus through intact soil cores collected from the adelaide hills, South Australia. Australian Journal of Soil Research 38:973-990. Dormaar, J.F., and C. Chang. 1995. Effect of 20 annual applications of excess feedlot manure on labile soil phosphorus. Canadian Journal of Soil Science 75:507-512. Dou, Z., Toth, J.D., Galligan, D.T., Ramberg, C.F., Jr., Ferguson, J.D. 2000. Laboratory procedures for characterizing manure phosphorus. Journal of Environmental Quality 29:508-514. Dou, Z.X., K.F. Knowlton, R.A. Kohn, Z.G. Wu, L.D. Satter, G.Y. Zhang, J.D. Toth, and J.D. Ferguson. 2002. Phosphorus characteristics of dairy feces affected by diets. Journal of Environmental Quality 31:2058-2065. Ebeling, A.M., L.R. Cooperband, and L.G. Bundy. 2003. Phosphorus source effects on soil test phosphorus and forms of phosphorus in soil. Communications in Soil Science and Plant Analysis 34: 13 & 14; 1897-1917.

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70 Eghball, B., G.D. Binford, and D.D. Baltensperger. 1996. Phosphorus movement and adsorption in a soil receiving long-term manure and fertilizer application. Journal of Environmental Quality 25:1339-1343. Elliott, H.A., B.A. Dempsey, and P.J. Maille. 1990. Content and fractionation of heavy-metals in water-treatment sludges. Journal of Environmental Quality 19:330-334. Edmeades, D.C. 2003. The long-term effects of manures and fertilisers on soil productivity and quality: a review. Nutrient Cycling in Agroecosystems 66:165-180. Gallimore, L.E., N.T. Basta, D.E. Storm, M.E. Payton, R.H. Huhnke, and M.D. Smolen. 1999. Water treatment residual to reduce nutrients in surface runoff from agricultural land. Journal of Environmental Quality 28:1474-1478. Goldwhite H. Introduction to phosphorus chemistry, 1981. New York: Cambridge University Press. Griffin, T.S., C.W. Honeycutt, and Z. He. 2003. Changes in soil phosphorus from manure application. Soil Science Society of America Journal 67:645-653. Guo, F.M., and R.S. Yost. 1998. Partitioning soil phosphorus into three discrete pools of differing availability. Soil Science 163:822-833. Haustein, G.K., T.C. Daniel, D.M. Miller, P.A. Moore, and R.W. McNew. 2000. Aluminum-containing residuals influence high-phosphorus soils and runoff water quality. Journal of Environmental Quality 29:1954-1959. He, Z., C.W. Honeycutt, and T.S. Griffin. 2003. Comparative investigation of sequentially extracted phosphorus fractions in a sandy loam soil and a swine manure. Communications in Soil Science and Plant Analysis 34:1729-1742. Hedley, M.J., J.W.B. Stewart, and B.S. Chauhan. 1982. Changes in inorganic and organic soil-phosphorus fractions induced by cultivation practices and by laboratory incubations. Soil Science Society of America Journal 46:970-976. Heil, D.M., and K.A. Barbarick. 1989. Water-treatment sludge influence on the growth of sorghum-sudangrass. Journal of Environmental Quality 18:292-298. Hieltjes, A.H.M., and L. Lijklema. 1980. Fractionation of inorganic phosphates in calcareous sediments. Journal of Environmental Quality 9:405-407. Holford, I.C.R., C. Hird, and R. Lawrie. 1997. Effects of animal effluents on the phosphorus sorption characteristics of soils. Australian Journal of Soil Research 35:365-373.

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71 Ippolito, J.A., K.A. Barbarick, D.M. Heil, J.P. Chandler, and E.F. Redente. 2003. Phosphorus retention mechanisms of a water treatment residual. Journal of Environmental Quality 32:1857-1864. Ippolito, J.A., K.A. Barbarick, and E.F. Redente. 2002. Combinations of water treatment residuals and biosolids affect two range grasses. Communications in Soil Science and Plant Analysis 33:831-844. Jackson, M.L 1958. Soil chemical analysis. Chapter 10: 227-271.Englewood Cliffs, N.J. Prentice Hall, Inc. Jones, J.B., Jr., and V.W. Case. 1991. Sampling, handling and analyzing plant tissue samples. p. 389-415. In R.L. Westerman (ed) Soil testing and plant analysis. 3 rd edition. Book Series No. 3. Soil Sci. Soc. Amer., Madison, WI. Koopmans, G.F., M.E. van der Zeeuw, W.J. Chardon, and J. Dolfing. 2001. Selective extraction of labile phosphorus using dialysis membrane tubes filled with hydrous iron hydroxide. Soil Science 166:475-483. Kuo, S., Phosphorus. 1996. Methods of soil analysis. Part 3 Chemical Analysis 869 919.SSSA Book Ser. 5. SSSA Madison, W.I.: Lu, P., and G.A. O'Connor. 2001. Biosolids effects on phosphorus retention and release in some sandy Florida soils. Journal of Environmental Quality 30:1059-1063. McDowell, R.W., A.N. Sharpley, L.M. Condron, P.M. Haygarth, and P.C. Brookes. 2001. Processes controlling soil phosphorus release to runoff and implications for agricultural management. Nutrient Cycling in Agroecosystems 59:269-284. McKelvey, V.E. 1973. Abundance and distribution of phosphorus in the lithosphere p 13-31. In Griffith E.J., A.E. Beeton, J.M. Spencer and D.T. Mitchell (ed). Environmental Phosphorus Handbook, Wiley-Interscience publication 1973. McKenzie, R.H., J.W.B. Stewart, J.F. Dormaar, and G.B. Schaalje. 1992. Long-term crop-rotation and fertilizer effects on phosphorus transformations .2. in a luvisolic soil. Canadian Journal of Soil Science 72:581-589. Mehlich, A. 1953. Determination of P, Ca, Mg, K, Na, and NH 4 Soil Testing Div. Publ. 1-53. North Carolina Department of Agriculture, Raleigh. Moore, P.A., T.C. Daniel, D.R. Edwards, and D.M. Miller. 1995. Effect of chemical amendments on ammonia volatilization from poultry litter. Journal of Environmental Quality 24:293-300. Nair, V.D., and D.A. Graetz. 2002. Phosphorus saturation in spodosols impacted by manure. Journal of Environmental Quality 31:1279-1285.

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72 Nair, V.D., D.A. Graetz, and D.O. Dooley. 2003. Phosphorus release characteristics of manure and manure-impacted soils. Food, Agriculture & Environment 2: 217-223. Nair, V.D., D.A. Graetz, and K.M. Portier. 1995. Forms of phosphorus in soil profiles from dairies of south florida. Soil Science Society of America Journal 59:1244-1249. OConnor, G.A., and H.A. Elliot. 2000. Co-application of biosolids and water treatment residuals. Final Report. Florida Department of Environmental Protection. Tallahassee, FL.Ohalloran, I.P., J.W.B. Stewart, and R.G. Kachanoski. 1987. Influence of Texture and Management-Practices on the Forms and Distribution of Soil-Phosphorus. Canadian Journal of Soil Science 67:147-163. O'Connor, G.A., H.A. Elliott, and R. Lu. 2002. Characterizing water treatment residuals phosphorus retention. Soil and Crop Science Society of Florida Proceedings 61:67-73. O'Hallorans, J.M., M.A. Munoz, and P.E. Marquez. 1997. Chicken manure as an amendment to correct soil acidity and fertility. Journal of Agriculture of the University of Puerto Rico 81:1-8. Pierzynski G.M., J.T. Sims and G.F. Vance, 2000. Soils and environmental quality p. 155-207. CRC Press, Boca Raton, Fl. Peters, J.M., and N.T. Basta. 1996. Reduction of excessive bioavailable phosphorus in soils by using municipal and industrial wastes. Journal of Environmental Quality 25:1236-1241. Pote, D.H., T.C. Daniel, D.J. Nichols, P.A. Moore, D.M. Miller, and D.R. Edwards. 1999. Seasonal and soil-drying effects on runoff phosphorus relationships to soil phosphorus. Soil Science Society of America Journal 63:1006-1012. Pote, D.H., T.C. Daniel, A.N. Sharpley, P.A. Moore, D.R. Edwards, and D.J. Nichols. 1996. Relating extractable soil phosphorus to phosphorus losses in runoff. Soil Science Society of America Journal 60:855-859. Rajan, S.S.S., K.W. Perrott, and W.M.H. Saunders. 1974. Identification of phosphate-reactive sites of hydrous alumina from proton consumption during phosphate adsorption at constant pH values. Journal of Soil Science 25:438-447. Reddy, D.D., A.S. Rao, and P.N. Takkar. 1999. Effects of repeated manure and fertilizer phosphorus additions on soil phosphorus dynamics under a soybean-wheat rotation. Biology and Fertility of Soils 28:150-155. Reddy, K.R., Y. Wang, W.F. DeBusk, M.M. Fisher, and S. Newman. 1998. Forms of soil phosphorus in selected hydrologic units of the Florida everglades. Soil Science Society of America Journal 62:1134-1147.

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73 Rhoades, J.D 1996. Salinity: electrical conductivity and total dissolved solids.In Methods of Soil Analysis. Part 3: 417-435. SSSA Book Ser. 5. SSSA Madison, W.I.: Robinson, J.S., and A.N. Sharpley. 1996. Reaction in soil of phosphorus released from poultry litter. Soil Science Society of America Journal 60:1583-1588. SAS Institute, 2001. The SAS system for windows. Version 8 Release 8.2 SAS Inst., Cary, NC. Sentran, T., and A. Ndayegamiye. 1995. Long-term effects of fertilizers and manure Application on the Forms and Availability of Soil-Phosphorus. Canadian Journal of Soil Science 75:281-285. Sharpley, A.N. 1996. Availability of residual phosphorus in manured soils. Soil Science Society of America Journal 60:1459-1466. Sharpley, A.N., S.C. Chapra, R. Wedepohl, J.T. Sims, T.C. Daniel, and K.R. Reddy. 1994. Managing agricultural phosphorus for protection of surface waters Issues and options. Journal of Environmental Quality 23:437-451. Sharpley, A.N., R.W. McDowell, and P.J.A. Kleinman. 2001. Phosphorus loss from land to water: integrating agricultural and environmental management. Plant and Soil 237:287-307. Sharpley, A., and B. Moyer. 2000. Phosphorus forms in manure and compost and their release during simulated rainfall (vol 29, pg 1462, 2000). Journal of Environmental Quality 29:2053-2053. Sharpley, A.N., and I. Sisak. 1997. Differential availability of manure and inorganic sources of phosphorus in soil. Soil Science Society of America Journal 61:1503-1508. Sharpley, A.N., S.J. Smith, B.A. Stewart, and A.C. Mathers. 1984. Forms of phosphorus in soil receiving cattle feedlot waste. Journal of Environmental Quality 13:211-215. SSSA. 1998. Soil science terms glossary [Online].Available at http://www.soils.org/sssagloss/search.html (verified 12 Mar. 2004). SSA, Madison, WI. Summers, R.N., N.R. Guise, and D.D. Smirk. 1993. Bauxite residue (Red Mud) increases phosphorus retention in sandy soil catchments in Western-Australia. Fertilizer Research 34:85-94. Tarkalson, D.D., and R.L. Mikkelsen. 2003. A phosphorus budget of a poultry farm and a dairy farm in the southeastern US, and the potential impacts of diet alterations. Nutrient Cycling in Agroecosystems 66:295-303.

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74 United States Environmental Protection Agency, 1984. Methods of chemical analysis of water and wastes, March, EPA-600/4-79-020, Environmental Monitoring Support Laboratory, Office of Research and Development,Cincinnati, OH 45286. Wang, H.D., W.G. Harris, K.R. Reddy, and E.G. Flaig. 1995. Stability of phosphorus forms in dairy-impacted soils under simulated leaching. Ecological Engineering 5:209-227. Ward, G.M., T.V. Muscato, D.A. Hill, and R.W. Hansen. 1978. Chemical composition of feedlot manure. Journal of Environmental Quality 7:159-164. Whalen, J.K., C. Chang, G.W. Clayton, and J.P. Carefoot. 2000. Cattle manure amendments can increase the pH of acid soils. Soil Science Society of America Journal 64:962-966. Wong, M.T.F., S. Nortcliff, and R.S. Swift. 1998. Method for determining the acid ameliorating capacity of plant residue compost, urban waste compost, farmyard manure, and peat applied to tropical soils. Communications in Soil Science and Plant Analysis 29:2927-2937. Zhang, M.K., Z.L. He, D.V. Calvert, P.J. Stoffella, Y.C. Li, and E.M. Lamb. 2002. Release potential of phosphorus in Florida sandy soils in relation to phosphorus fractions and adsorption capacity. Journal of Environmental Science and Health Part a-Toxic/Hazardous Substances & Environmental Engineering 37:793-809. Zhang, M.K., Z.L. He, D.V. Calvert, P.J. Stoffella, X.E. Yang, and Y.C. Li. 2003. Phosphorus and heavy metal attachment and release in sandy soil aggregate fractions. Soil Science Society of America Journal 67:1158-1167. Zheng, Z.M., R.R. Simard, J. Lafond, and L.E. Parent. 2002. Pathways of soil phosphorus transformations after 8 years of cultivation under contrasting cropping practices. Soil Science Society of America Journal 66:999-1007.

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BIOGRAPHICAL SKETCH Leighton Walker was born in Mandeville, Jamaica, on February 22 nd 1979. He is the youngest of five children born to Herbert Walker and Valerie Walker. For his undergraduate education, Leighton attended the University of the West Indies in Trinidad and participated in a student exchange programme at Virginia Polytechnic and State University, after which he received his Bachelor of Science degree in general agriculture. After graduating in 2000, he returned to Jamaica for a few months. In August 2001, Leighton started his masters degree in the Soil and Water Science Department at the University of Florida. 75


Permanent Link: http://ufdc.ufl.edu/UFE0004917/00001

Material Information

Title: Vertical mobility and dynamics of phosphorus from fertilizer and manure in sandy soils
Physical Description: xi, 75 p.
Language: English
Creator: Walker, Leighton Croft ( Dissertant )
Graetz, D. A. ( Thesis advisor )
Nair, Vimala D. ( Thesis advisor )
Harris, W. ( Reviewer )
Nordstedt, R. ( Reviewer )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2004
Copyright Date: 2004

Subjects

Subjects / Keywords: Soil and Water Science thesis, M.S   ( local )
Dissertations, Academic -- UF -- Soil and Water Science   ( local )

Notes

Abstract: Animal manures from intensive livestock operations are rich sources of nutrients such as phosphorus (P) which are vital for plant growth. Increased amounts of P in water bodies may lead to unwanted environmental and aesthetic damages to these aquatic ecosystems. Some types of land-applied animal manures may release P even more easily than commercial P fertilizers when in contact with rainwater. The coarse textured sandy soils of Florida are prone to losing P both by surface runoff and leaching down through the soil profile. A column leaching study was conducted on coarse textured sandy soils with different nutrient management histories (high and low impact by manures) from two commercial dairy farms. Soil columns were treated with three P sources (dairy storage pond effluent, inorganic fertilizer and broiler litter compost), each applied at a rate equivalent to 40 kg P ha⁻±. ABSTRACT: The objective of this study was to compare the leaching potential of the three P sources applied to low and highly manure-impacted sandy soils, and also to evaluate the effects of an aluminum based water treatment residual (WTR) on P leaching. Soil columns (25cm L * 7.5 cm I.D.) were leached with simulated rainfall over a 19 week period. Leachate was collected at each leaching event, and at the end of the study, the soil was sectioned into three depth increments to evaluate the movement of P within the column. The low manure impacted soil leached overall approximately five times less P than the highly impacted soil. The dairy storage pond effluent treated soils leached P more easily and in greater amounts than the remaining soil treatments. Leachates of dairy storage pond effluent treated soils had higher electrical conductivity (EC) and pH values than the leachates of the remaining treatments. ABSTRACT: The Al-WTR reduced the quantities of P leached within P source treatments of the low manure impacted soil by 18-33% and from the high impact soil P source treatments (excluding the control) by 16-22%. It was, however, less effective at reducing the quantities of P leached from dairy effluent treated soil columns when compared to the remaining P sources. The soil columns containing the added Al-WTR had significantly (P = 0.05) greater quantities of soil P stored as the stable iron (Fe) and aluminum Al bound P.
Subject: broiler, compost, dairy, effluent, fertilizer, leachates, leaching, litter, manures, phosphorus, residuals, treatment, water
General Note: Title from title page of source document.
General Note: Document formatted into pages; contains 86 pages.
General Note: Includes vita.
Thesis: Thesis (M.S.)--University of Florida, 2004.
Bibliography: Includes bibliographical references.
General Note: Text (Electronic thesis) in PDF format.

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0004917:00001

Permanent Link: http://ufdc.ufl.edu/UFE0004917/00001

Material Information

Title: Vertical mobility and dynamics of phosphorus from fertilizer and manure in sandy soils
Physical Description: xi, 75 p.
Language: English
Creator: Walker, Leighton Croft ( Dissertant )
Graetz, D. A. ( Thesis advisor )
Nair, Vimala D. ( Thesis advisor )
Harris, W. ( Reviewer )
Nordstedt, R. ( Reviewer )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2004
Copyright Date: 2004

Subjects

Subjects / Keywords: Soil and Water Science thesis, M.S   ( local )
Dissertations, Academic -- UF -- Soil and Water Science   ( local )

Notes

Abstract: Animal manures from intensive livestock operations are rich sources of nutrients such as phosphorus (P) which are vital for plant growth. Increased amounts of P in water bodies may lead to unwanted environmental and aesthetic damages to these aquatic ecosystems. Some types of land-applied animal manures may release P even more easily than commercial P fertilizers when in contact with rainwater. The coarse textured sandy soils of Florida are prone to losing P both by surface runoff and leaching down through the soil profile. A column leaching study was conducted on coarse textured sandy soils with different nutrient management histories (high and low impact by manures) from two commercial dairy farms. Soil columns were treated with three P sources (dairy storage pond effluent, inorganic fertilizer and broiler litter compost), each applied at a rate equivalent to 40 kg P ha⁻±. ABSTRACT: The objective of this study was to compare the leaching potential of the three P sources applied to low and highly manure-impacted sandy soils, and also to evaluate the effects of an aluminum based water treatment residual (WTR) on P leaching. Soil columns (25cm L * 7.5 cm I.D.) were leached with simulated rainfall over a 19 week period. Leachate was collected at each leaching event, and at the end of the study, the soil was sectioned into three depth increments to evaluate the movement of P within the column. The low manure impacted soil leached overall approximately five times less P than the highly impacted soil. The dairy storage pond effluent treated soils leached P more easily and in greater amounts than the remaining soil treatments. Leachates of dairy storage pond effluent treated soils had higher electrical conductivity (EC) and pH values than the leachates of the remaining treatments. ABSTRACT: The Al-WTR reduced the quantities of P leached within P source treatments of the low manure impacted soil by 18-33% and from the high impact soil P source treatments (excluding the control) by 16-22%. It was, however, less effective at reducing the quantities of P leached from dairy effluent treated soil columns when compared to the remaining P sources. The soil columns containing the added Al-WTR had significantly (P = 0.05) greater quantities of soil P stored as the stable iron (Fe) and aluminum Al bound P.
Subject: broiler, compost, dairy, effluent, fertilizer, leachates, leaching, litter, manures, phosphorus, residuals, treatment, water
General Note: Title from title page of source document.
General Note: Document formatted into pages; contains 86 pages.
General Note: Includes vita.
Thesis: Thesis (M.S.)--University of Florida, 2004.
Bibliography: Includes bibliographical references.
General Note: Text (Electronic thesis) in PDF format.

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0004917:00001


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VERTICAL MOBILITY AND DYNAMICS OF PHOSPHORUS FROM
FERTILIZER AND MANURE IN SANDY SOILS

















By

LEIGHTON CROFT WALKER


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


2004

































Copyright 2004

by

Leighton Croft Walker

































This document is dedicated to my parents Mr. Herbert Walker and Mrs. Valerie Walker.















ACKNOWLEDGMENTS

Thanks go to my committee Dr. D. Graetz (chair), Dr. V.D. Nair (cochair), Dr. W.

Harris and Dr. R. Nordstedt for working arduously with me and providing me the

necessary guidance in completing this research. I would also like to thank my laboratory

manager Mrs. Dawn Lucas and my fellow lab mates and colleagues in the department.

The warm support of my parents Mr. Herbert Walker and Mrs. Valerie Walker, and

my siblings Denver, Kerry, Shajni and Allistair and their families was a major

motivational factor. My fiancee and soon to be wife Sonia was also very supportive for

which I was especially appreciative.

Above everyone else, I thank my God and Creator without whom there would not

be even a possibility of starting or even completing this degree.
















TABLE OF CONTENTS

page

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

LIST O F TA BLE S ............................ ........... ..... ......... ............ .. vii

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

A B ST R A C T ................. .......................................................................................... x

CHAPTER

1 IN TRODU CTION ................................................. ...... .................

2 LITER A TU R E REV IEW .............................................................. ....................... 4

3 MATERIALS AND METHODS ........................................ ......................... 20

S o ils ..............................................................................2 0
C olu m n L teaching Stu dy .............................................................................................2 1
C olu m n S etu p ....................................................... 2 1
A analytical Procedures ................................................. .. .. ........ .............. .. 25
S o il A n a ly sis .................... ........................................................................... 2 5
P Source/ A m endm ent A analysis .................................. ...................................... 25
L eachate A naly sis............ ..... ... ........ .... .......................... ......... ...... ....26
Water Treatment Residual Analysis ............ .............................................26
Soil Fractionation ...................... .................. ................... ..... .... 26
Statistical A n aly ses........... ...... .................................................. .... .... ... .... 2 8

4 RESULTS AND DISCU SSION ........................................... .......................... 30

Soil Characterization ....................... .................. ... .... ........ ......... 30
A m endm ent Characterization ............................................................. ...............31
L eachate C haracterization ........................................ ....................................... 1
p H .............. ........ ..................... ......................................... . 3 1
E electrical C onductivity ..................................... ....... ................. ............... 37
P h o sp h o ru s ................................................................4 1
F ra ctio n atio n ....................................................................................................4 5

5 C O N C L U SIO N ......... ...................................................................... .. .......... ..... .. 53


v









APPENDIX

A PHOSPHORUS CONCENTRATIONS OF FERTILIZERS AND MANURES
AND THE QUANTITIES OF EACH APPLIED TO EACH SOIL COLUMN .......55

B PERCENT CHANGES IN SOIL PHOSPHORUS FRACTIONS OBSERVED
THE FOR BYRD DAIRY AND OAK GROVE SOILS ............................................56

C PHOSPHORUS CONCENTRATIONS FOR THE BYRD DAIRY AND OAK
G R O V E L E A C H A TE S ..................................................................... ...................64

L IST O F R E F E R E N C E S ....................................................................... .... .................. 68

BIOGRAPH ICAL SKETCH ...................................................... 75
















LIST OF TABLES


Table pge

3-1 Chemical components of simulated rainwater .............. ............ .....................22

4-1 Selected Chemical Properties of the Ap Horizons of the Byrd
Dairy and Oak Grove Dairy soils (n = 6). ...................................... ............... 30

4-2 Selected properties of the Al-WTR used in the study (O'Connor
and E lliot, 2000).......................................................................... .3 1

4-3 Phosphorus fractions, oxalate extractable P, Fe, and Al and P
sorbing capacity of the Al-WTR (O'Connor and Elliot, 2000)............................. 31

4-4 p values for Hydronium ion concentrations of the Byrd Dairy
and Oak Grove soil column leachates for the 1st leaching event. ..........................32

4-5 Average pH values of the Byrd Dairy soil column leachates for
the 1st leaching event. ...................... ................ ................. .... ....... 32

4-6 p values for Hydronium ion concentrations of the Byrd Dairy
and Oak Grove soil column leachates for the 19th leaching event .........................33

4-7 Average pH values of the Byrd Dairy soil column leachates for the
19th leaching event ....................................... ............ .. .. .. ........ .... 33

4-8 Average pH values of the Oak Grove soil column leachates for the
1st leaching event. ..................................................................... 35

4-9 Average pH values of the Oak Grove soil column leachates for the 19th leaching
ev ent. .............................................................................. 3 5

4-10 SRP amounts leached from BD and OG soils over 19 leaching events................43

4-11 TP amounts leached from BD and OG soils over 19 leaching events ...................43

4-12 p values for interactions for the BD soil. (P = 0.05). ............................................. 46

4-13 Sequential data for amounts ofP (tg P/g) in the soil P fractions in
the B yrd D airy soil. ............................................. ................... .. .....48

4-14 p values for interactions for the OG soil (P=0.05) .............................................50









4-15 Sequential data for amounts ofP (tg P) in the soil P fractions in the
O ak G rove soil. ....................................................................... 52















LIST OF FIGURES


Figure pge

3-1 Diagram of leaching column containing soil and treatment ..................................24

3-2 Schematic of the modified fractionation procedure adopted from Hedley et al.
(19 82). .............................................................................. 2 9

4-1 Trends in pH changes observed for theByrd Dairy soil. (A) Amended column
leachates. (B) Unamended column leachates. .................. .............................. 34

4-2 Trends in pH changes observed for the Oak Grove soil. (A) Amended column
leachates. (B) Unamended column leachates. .................. .............................. 36

4-3 Average electrical conductivity values for leachates collected from columns
containing different P source treatments for the Byrd Dairy soil. (A) Amended
column leachates. (B) Unamended column leachates...................... ...............38

4-4 Average electrical conductivity values for leachates collected from columns
containing different P source treatments for the Oak Grove soil. (A) Amended
column leachates. (B) Unamended column leachates...................... ...............39













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

VERTICAL MOBILITY AND DYNAMICS OF PHOSPHORUS FROM
FERTILIZER AND MANURE SOURCES IN SANDY SOILS
By

Leighton Croft Walker

May 2004

Chair: D.A. Graetz
Cochair: V.D. Nair
Major Department: Soil and Water Science

Animal manures from intensive livestock operations are rich sources of nutrients

such as phosphorus (P) which are vital for plant growth. Increased amounts of P in water

bodies may lead to unwanted environmental and aesthetic damages to these aquatic

ecosystems. Some types of land-applied animal manures may release P even more easily

than commercial P fertilizers when in contact with rainwater. The coarse textured sandy

soils of Florida are prone to losing P both by surface runoff and leaching down through

the soil profile.

A column leaching study was conducted on coarse textured sandy soils with

different nutrient management histories (high and low impact by manures) from two

commercial dairy farms. Soil columns were treated with three P sources (dairy storage

pond effluent, inorganic fertilizer and broiler litter compost), each applied at a rate

equivalent to 40 kg P hal-. The objective of this study was to compare the leaching

potential of the three P sources applied to low and highly manure-impacted sandy soils,

and also to evaluate the effects of an aluminum based water treatment residual (WTR) on









P leaching. Soil columns (25cm L 7.5 cm I.D.) were leached with simulated rainfall

over a 19 week period. Leachate was collected at each leaching event, and at the end of

the study, the soil was sectioned into three depth increments to evaluate the movement of

P within the column.

The low manure impacted soil leached overall approximately five times less P than

the highly impacted soil. The dairy storage pond effluent treated soils leached P more

easily and in greater amounts than the remaining soil treatments. Leachates of dairy

storage pond effluent treated soils had higher electrical conductivity (EC) and pH valeus

than the leachates of the remaining treatments.

The Al-WTR reduced the quantities of P leached within P source treatments of the

low manure impacted soil by 18-33% and from the high impact soil P source treatments

(excluding the control) by 16-22%. It was, however, less effective at reducing the

quantities of P leached from dairy effluent treated soil columns when compared to the

remaining P sources. The soil columns containing the added Al-WTR had significantly

(P = 0.05) greater quantities of soil P stored as the stable iron (Fe) and aluminum Al

bound P.














CHAPTER 1
INTRODUCTION

The increasing number of intensive cattle and poultry operations in the United

States (US) is creating ever increasing amounts of manures as by-products. Manures are

very rich in nutrients which can be utilized as fertilizers for crop production. Some

manure types may even as effective as commercially available chemical fertilizers at

providing P to crops. Land application rates of these manures needs to be tailored

according to the respective soils and crops receiving them in order to ensure optimal

agronomic and environmental benefits. Nitrogen (N) and phosphorus (P), two major

nutrients in these manures, are a major concern with regard to water quality.

Eutrophication, which results from the over enrichment of water bodies with these

nutrients, is a major problem. Eutrophication is an excessive growth of plant biomass in

water bodies in response to excesses of N and P (Perzynski et al., 2000). This has a

number of undesirable effects on the quality of aquatic systems, the chief one being the

rapid exhaustion of dissolved oxygen (DO). The levels of DO in these waters are rapidly

depleted when plants die and microbes use the DO in the decomposition of the dead plant

material. Unavailability of DO is detrimental for aquatic animals resulting in disastrous

ecological effects such as fish kills. Eutrophication of water bodies may have numerous

other negative effects, such as elimination of desired plant and animal species, disruption

of aquatic food chain, and even loss of aesthetic and recreational value of water bodies.

Excessive N loss from agricultural operations to water bodies has long been treated

in the US as a potential source of environmental pollution. As a result of this, agronomic









recommendations were being made on an N basis. Levels of P were not being considered

for some time, and soils were being loaded with P unnoticed (McDowell et al., 2001;

Sharpley et al., 1994). It is clearly evident that the eutrophication process is dependent on

both nutrients.

Florida has many intensive livestock operations, particularly poultry and dairy

farms, which create large quantities of animal manures rich in P as wastes which are

land-applied to grow hay and other crops. Application of manures to soils that have low P

retention capacity, as in the case of many soils in Florida, increases the potential of P loss

from land application of manures. Currently, a P risk assessment index is being

developed to determine the vulnerability of manure application sites in order to minimize

harmful environmental impacts (Nair and Graetz, 2002). Of paramount importance in

developing this P-index is an understanding of the dynamics, availability and movement

of P from manures as compared to fertilizers to the environment. Increasing retentive

capacity of soils by using soil amendments is also a very promising and useful possibility

(Anderson et al., 1995; Callahan et al., 2002; Codling et al., 2002).

Although leaching or movement ofP vertically through soil profiles has generally

not been considered an environmental issue, recent studies have shown that leaching of P

can occur in some soils. This is particularly true in coarse textured soils with low P

retention capacity. Inorganic chemical fertilizers have generally been thought of as being

more at risk of losing P to the environment (Emeades, 2003). However, it has been shown

that P may leach more readily from animal manures than from commercial fertilizers

(Eghball et al., 1996).









Water treatment residuals are by-products of the drinking water treatment industry.

They are generally used to flocculate and settle out nutrients such as P, chemical

impurities and debris from raw waters that are treated for domestic use. They generally

consist of compounds containing either aluminum (Al), calcium (Ca), iron or (Fe), three

elements which have the capacity to bind and retain P. It is thus of merit that WTRs be

evaluated to see if they can be as beneficial agriculturally as they are in the drinking

water treatment industry.Thus, the objectives of this study were to evaluate: 1) the P

leaching characteristics of two coarse textured soils with low P retention capacity using

three P sources (dairy effluent, poultry litter, and triple superphosphate fertilizer)and, 2)

the effectiveness of a water treatment residual (WTR) for reducing the leaching of P from

the soils treated with the various treatments above.














CHAPTER 2
LITERATURE REVIEW

Phosphorus (P) is an ubiquitous element being found almost everywhere on the

planet. It forms approximately 0.1% of the rocks that make up the bulk of the earth's

crust, most of which occur in species of phosphorus-rich minerals called the apatite group

Ca5(PO4, CO3)3(F, Cl, OH), the most common of which is fluorapatite Ca5(PO4)3F

(McKelvey, 1973). As the eleventh most abundant element on earth (McKelvey, 1973), P

plays a very important role in the metabolic functions of all living organisms. It is an

essential component of nucleic acids and many intermediary metabolites such as sugar

phosphates and adenosine phosphates, which are an integral part of the metabolism of all

life forms (Correll, 1998). The major energy storage and transfer mechanisms in all living

things is dependent on the breakdown of the ester linkages of adenosine diphosphate

(ADP) and adenosine triphosphate (ATP), while storage and transfer of coded genetic

information involves nucleic acids which are diesters of phosphoric acid

(Goldwhite, 1981).

Despite the widespread presence of P in the earth, only a fractional percentage of

the total P in the lithosphere is concentrated in deposits consisting mainly of phosphate

minerals (McKelvey, 1973). It must therefore often be added to soil to provide adequate

amounts for plant growth.

The commercial production of inorganic chemical phosphorus fertilizers which are

applied to crops has been the conventional way of supplying the P needs of agricultural

crops. There has been a notion that these chemical fertilizers in general are more likely to









have detrimental effects on soil and water quality, and this has lead to some promotion of

the use of so called 'natural' sources of nutrients such as manures, to fertilize crops

(Emeades, 2003).

However, amending the soil with both, P-containing fertilizers and animal manures

has increased the risk for P loss from the land and subsequent transport to rivers and

lakes. In the United States, areas of intensive agricultural operations are major potential

non-point sources of pollution of water bodies by eutrophication. Eutrophication as

defined by Perzynski et al., (2000), is "an increase in the fertility status of natural waters

that causes accelerated growth of algae or plant material". The nutrients nitrogen (N) and

P are often associated with eutrophication. Phosphorus is most often the element limiting

accelerated eutrophication. This is because most blue-green algae are able to utilize N

from the atmosphere (Pote et al., 1996).

Although the total amount of P loaded to surface runoff and stream flow is

important to water quality, the forms or fractions of P in soils that are released into the

waters are probably more critical (Zhang et al., 2002). Numerous attempts have been

made to define and identify environmentally available (labile) fractions in soils. In

aquatic systems, P only occurs in pentavalent forms such as orthophosphate,

pyrophosphate, longer-chain polyphosphates, organic phosphate esters and

phosphodiesters, and organic phosphonates (Correll, 1998). Orthophosphate is the only

pentavalent form of P which can be assimilated by bacteria, algae and plants. Phosphorus

entering receiving waters is a complex of these pentavalent forms as dissolved and

particulate inputs. The particulates may release phosphorus compounds to solution which

may be chemically or enzymatically hydrolized to orthophosphate (Correll, 1998).









Dissolved P is comprised mostly of orthophosphate, which is immediately available for

algal uptake (Sharpley et al., 1994).

Existing agronomic guidelines may not be appropriate for water quality protection.

Agronomic soil test interpretations are based on the expected response of a crop to P, and

cannot be directly translated to estimates of environmental risk (Sharpley et al., 2001). In

this document, environmentally labile P will refer to P considered to be directly or

potentially algae-available. The Soil Science Society of America Glossary of Soil Science

Terms (2003) defines the labile pool ofP as "that portion which is readily solubilized or

exchanged when the soil is equilibrated with a salt solution and the available pool as the

amount of soil P in chemical forms accessible to plant roots or compounds likely to be

convertible to such forms during the growing season". A modification of this definition

for the purposes of this review will consider the labile P pool to be the soil fractions

which are readily solubilized in a salt solution or water and those fractions fixed to the

solid surfaces which may solubilize when exposed to a solution of low P concentration.

The inclusion of these potentially soluble fractions is necessary because, with the

addition of water (rainfall, groundwater etc.) to soils, the soil solution P concentration

changes, and a new equilibrium is established between the soil, and the soil solution

phases. This results in adsorption-desorption reactions taking place whereby P, especially

water-soluble forms that are attached to particle surfaces will be readily released to the

soil solution (Zhang et al., 2003), until equilibrium is reached. This equilibrium where a

solution P concentration is reached such that no further adsorption or desorption takes

place is called the equilibrium P concentration or EPCo. A dilute solution of 0.01 M









calcium chloride can be used to extract P that is a measure of the available soil P (Kuo,

1996).

There is no standard soil extraction technique to identify the labile P fractions.

There have been variations in the interpretations of labile P fractions. Nair et al. (1995)

defined 1M NH4C1 as representing the labile P in a modified version of the Hieltjes and

Lijklema (1980) fractionation scheme. Soil P fractionation is a technique which uses a

series of chemical extractants to sequentially remove various chemical P forms. Mild

chemical extractants are used to remove the labile fractions followed by increasingly

harsher extractants which remove less labile P fractions.

Pote et al. (1996) found distilled water (DI), ammonium oxalate and Fe oxide paper

strips were effective at approximating P available to growing algae while Koopmans et

al. (2001) noted that DI and CaC12 extractable P represent the more labile forms of P in

soil. Other authors include potassium chloride (IN KC1) and or sodium bicarbonate

(0.5M NaHCO3) extractible inorganic phosphorus (Pi) in this labile fraction (Reddy et al.,

1998; Sharpley, 1996). Hedley et al. (1982) used the NaHCO3 extractable P fraction to

represent labile Pi and organic phosphorus (Po) sorbed to soil surfaces. Robinson and

Sharpley (1996) referred to this soil P fraction in acid to neutral soils as a reversible P

fraction. Zhang et al. (2002) found that the sum of the NaHCO3 Pi and Po fractions in

sandy Florida soils was a good indicator of soil potential to release labile P. He et al.

(2003) also found that NaHCO3 was a mild extractant only responsible for the removal of

P physically attached to soil surfaces.

As noted above, various soil test methods, fractionation procedures and

mechanistic approaches have been used to estimate labile soil P. However, the









complexity of the chemistry and mineralogy of soil makes P availability a continuum.

Thus, unequivocal identification of labile compounds or fractions is difficult (Guo and

Yost, 1998). However, the sequential procedure introduced by (Hedley et al., 1982) has

often been used to fractionate soil P. Increasingly harsh extractants remove P fractions

that are increasingly less labile. Slight modifications are sometimes made to the original

procedure as is the case in this study. The fractionation extractants/steps and their

associated P fractions are CaC12 (water soluble Pi), NaHCO3 (Pi and Po mainly sorbed to

soil surfaces and considered labile), NaOH (less labile Al and Fe bound Pi and Po), HC1

(unavailable Ca and magnesium (Mg) bound Pi), and residual P (unavailable or

recalcitrant Po). Water soluble P along with NaHCO3 Pi and Po will be considered as the

labile soil fractions in this study.

Phosphorus is supplied to field crops as inorganic fertilizers or organic materials

such as manures. Many manure management recommendations are based on fertilizer

response (Sharpley and Sisak, 1997) but P availability and appropriate application rates

may differ between sources. The P content of manures must not be overlooked because as

much as 70% of P in feed ingested by animals in intensive livestock operations is

excreted (Sharpley et al., 2001). The availability of P, however, is not dependent on the

total amounts of added P, but rather upon the characteristics of the P source applied to the

soil (Ebeling et al., 2003). Along with understanding the constituents of manures, it is

also important to know how manures affect the soil constituents (Nair et al., 2003). In

developing manure management guidelines that are both agronomically and

environmentally sound, the fate of manure P should be considered (Robinson and

Sharpley, 1996). Several authors have pointed out that there are different effects on soil P









pools with the use of fertilizers versus manures (Campbell et al., 1986; Ohalloran et al.,

1987; Reddy et al., 1999; Sentran and Ndayegamiye, 1995). The pools of soil P and their

relative distributions are important because they may be responsible in controlling the

extent of P leaching (Zhang et al., 2003). Phosphorus transformations in soils involve

complex mineralogical, chemical and biological processes (Zheng et al., 2002) and are

dependent on a number of interactions such as inherent soil properties, P removal by

crops, climatic conditions (Reddy et al., 1999) and P source characteristics. In the

literature, the documented effects of the various types of added fertilizers and manures,

on soil P pools and availability have varied based on at least one or a combination of the

above mentioned interactions.

The composition of manures vary, but Pi present in animal manure types is

generally high and range from 60 to 90% (Barnett, 1994a; Sharpley and Moyer, 2000).

The amount and forms of P excreted depend on a number of factors such as the

physiological state of the animal, the dietary levels and the feed source (Barnett, 1994b).

Poultry are monogastric and require additional inorganic P to supplement their diets

(Tarkalson and Mikkelsen, 2003). This results in poultry manure having higher Pi

contents. In a study with three different manure types, Nair et al. (2003) found that dairy

manures leached the least amount of labile P while beef cattle manure leached the

greatest amount despite the total P (TP) amounts being in the reverse order. Ebeling et al.

(2003) also found that manures of dairy cows without supplemental inorganic P have less

potential for contributing P in runoff when land applied.

Sharpley and Moyer (2000), in a study using four manures and two composts,

found a Pi range in samples from 63 to 92%. In that same study, the water-soluble and









NaHCO3 P ranged froml6 to 63% and 11 to 39% respectively. Dou et al. (2000) reported

results with water-soluble and NaHCO3 P fractions of, 70 and 14% and 49 and 19%,

respectively, for dairy and poultry manures. This means that manures, like fertilizers,

may have the potential to contribute high amounts of P to the labile and moderately labile

soil P pools. Sentran and Ndayegamiye (1995) found that both manure and fertilizer

applications to a silt loam increased labile and moderately labile Pi. Sharpley et al. (1984)

also found that cattle feedlot waste increased all forms of Pi in the soils to which they

were applied. In another study by Sharpley (1996), using Fe-oxide strips to extract labile

P from a range of agricultural soils with previous manure applications, each a different

type, found that most of the Fe-oxide strip P after 15 successive extractions was from the

NaHCO3 Pi soil fraction. Reddy et al. (1999) found manure application to increase all soil

P pools except HCl-extractable P. Other studies have found similar significant increases

in some or all pools of soil Pi in particular labile and moderately labile pools. These

increases in Pi pools in soils may be because of the high Pi contents of the manures

(Sharpley et al., 1984), decreased soil P sorption because of manure addition (Reddy et

al., 1999), or conversion of soil Po fractions to Pi fractions induced by mineralization

from increased microbial activity (Sentran and Ndayegamiye, 1995).

Nair et al. (1995) also pointed out another important effect that dairy manure

applications have on the soil P forms. They found that the A horizons of several soils

which had dairy applications were dominated by Ca and Mg associated P which were in

somewhat unstable associations. The susceptibility of the Ca and Mg associated P in

these soils to constant and easy removal when subjected to leaching was also noted.

Repeated extractions of the soil with 1M NH4C1 showed constant removal of P and a









corresponding decline in the HC1 soil P pool which in most soils is usually considered to

be one of the most resistant pools.

The efficiency of uptake by crops of applied P for fertilization is often low and

rarely exceeds 20% of applied P in the year of application (Reddy et al., 1999). Soils of

crop fields in intensive animal operations that are over-fertilized with P from manure

relative to crop requirements (Carefoot and Whalen, 2003) will in the short-term run the

risk of having high levels of labile P fractions which may be potential pollutants. This

was noted in a study by Dormaar and Chang (1995) where high levels (15 and 46%) of

labile P were observed in plots fertilized by manures. There is, however, the explanation

that the Pi fractions from P added in excess of crop uptake is readsorbed onto soil

components (Hedley et al., 1982; Reddy et al., 1999). This is however dependent on the

loading status and capacity of the particular soil and the timing of the application with

regard to rainfall events.

The climatic conditions of a region may also affect the fractions of P in a soil. Dou

et al. (2002), mentioned the potential pollution threat that easily soluble P forms in

manure applied to fields could pose if dissolved in rainwater. In a simulated rainfall study

Sharpley and Moyer (2000) leached between 15and 58% of the total P applied using six

different P sources (dairy manure, dairy compost, poultry manure, poultry litter, poultry

compost and swine slurry) of which dairy manure leached the highest amount. In soils

where leaching of bases and carbonates occurs, there is an increase in Al and Fe activity

(Zheng et al., 2002) which may transform labile sources of Pi and Po to less labile Pi.

Griffin et al. (2003) noted that labile P pools when applied to sandy loam soils, were

sorbed rapidly onto soil Al and Fe when manures were applied. The latter soil however









had high Mehlich-3 Al and Fe values. In the same study, the effect of wet-dry cycles on P

pools was seen in two- to threefold increases of CaC12 extractable P for soils with

manures added. Pote et al. (1999) also noted levels of runoff P in soils subjected to wet-

dry cycles varied seasonally.

The inherent properties of a soil also influence the pools of soil P which will exist

when manures and fertilizers are applied to agricultural lands. Zheng et al. (2002) pointed

to work done by Beck and Sanchez (1994) on a previously unfertilized soil. On addition

of fertilizer to this soil the NaOH Pi fraction acted as a sink for fertilizer P. McKenzie et

al. (1992) found NaHCO3 and NaOH pools in an unlimed fertilized acid soil to be higher

than similar limed (pH 1.1-1.5 units higher) plot. The texture of soils (clay and carbon

contents) also influences the forms and amounts of P that are available (Griffin et al.,

2003; Sharpley and Sisak, 1997) when manures are added. Sandy soils generally retain

less P than finer-textured soils because of a deficiency of Al and Fe oxides, clay and

organic matter. It is generally believed that significantly large amounts ofP will not leach

through soils with high amounts of clay because the P will be adsorbed onto the Al and

Fe hydroxides and oxides (Cox et al., 2000; Rajan et al., 1974). However the pore size of

the soil type can be very important in determining the effectiveness of even clay rich soils

in retarding P movement. Cox et al. (2000) pointed to previous work in which P mobility

was observed in clay, Fe and Al rich soils with macropores.

Phosphorus sorption capacity is clearly the most important factor controlling the

leaching potential of P from soils. The partitioning of P between the soil solution and

solid phases and P release in a soil, is controlled by the sorption capacity (Zhang et al.,

2003). The importance of the P application history on whether soils even retain P forms









was highlighted by Holford et al. (1997). They found that, the application of manures to a

soil with very little P application history had no effect on its sorption capacity. Phosphate

sorption is dependent on a number of factors such as temperature, pH, soil solution

concentration, aeration and time. The P application history of a piece of land to which

further application of P is taking place has to be considered when assessing the sorption

capacity of a soil. This is because the effective sorption capacity of these soils may

change from that of the soil in its initial pre-fertilization stage. The time factor is of great

importance in considering the effect of fertilization on soils with long fertilization

histories. Generally it is accepted that the kinetics of P adsorption involves an initially

rapid reaction lasting usually a few hours, followed by a second reaction at a much

slower rate. The first reaction is believed to involve physical sorption onto the soil

surfaces while the second involves chemisorption where P diffuses into the structurally

porous soil particles (Barrow et al., 1998).

The saturation of soil P sorption sites is a generally accepted mechanism in

explaining the decrease in sorption of previously fertilized soils (with manure or

fertilizer). Sharpley (1996) found that the rates and quantities of P released in his

experiment were a function of soil P sorption saturation. This however, may not be the

only mechanism or even the major mechanism in all cases. Diffusive penetration into

variable charge surfaces may change the electrical potential of the surfaces making them

more negative, thus enhancing desorption and reducing sorption of P (Barrow, 1999),

possibly before the saturation of soil sorption sites. Phosphorus sources applied to soils

then are able to reduce the effective P sorption capacity of a soil in subsequent P

applications (Barrow et al., 1998). The continuous reaction of applied P with soil









particles decreases the sorption capacity of soils with subsequent new additions of P has

also been shown on sandy soils in Australia (Barrow et al., 1998).

Sandy soils in comparison to fine-textured soils are very vulnerable to the leaching

of P as a result of their generally low sorption capacity and macroporous nature. The

most effective way to manage P mobility in these soils is, either to reduce the P loading

or to increase the P sorption capacity. Currently the most feasible environmental and

economic solution to this problem is the application of solid phase materials containing

Al, Ca and Fe to lands with high rates of constant P loading. Various soil amendments

have been and are being used to increase the P sorption capacity of soils (Gallimore et al.,

1999; Haustein et al., 2000; O'Connor et al., 2002; Peters and Basta, 1996; Summers et

al., 1993). These amendments are normally high in Al, Ca or Fe containing materials and

residues which are usually by-products of various industries, some major ones being, the

coal mining industry, the bauxite mining industry, the steel processing industry and the

water treatment industry. The amendment used is sometimes dependent on its availability

and economic feasibility for land application. However, there are problems with some of

these amendments. Whereas some may be of low cost or even cost free and easily

transported to agricultural land, they may not be environmentally beneficial. These

industrial waste or by-products may contain very high levels of dangerous and toxic

metals and compounds which may be detrimental to plants, animals and even humans.

Bauxite red mud, a waste product of the bauxite mining/alumina industry is classified as

a hazardous material. It contains large amounts of lye, soluble sodium (Na), aluminate

and is highly corrosive (Peters and Basta, 1996).









Materials generated from the water treatment industry will most likely have a very

high capacity to immobilize soluble P and are currently being evaluated for their potential

as soil amendments. Biosolids and water treatment residuals (WTRs) are the two main

by-products from the water treatment industry. Work has been done with biosolids and

they have been proven to be effective soil amendments, while work on WTRs is still in

its somewhat early stages (Ippolito et al., 2002). Biosolids are classified as by-products of

wastewater treatment plants, whereas WTRs are a waste product of drinking water

treatment (Ippolito et al., 2002).

Water treatment residuals are typically derived from the processes of coagulation,

flocculation and sedimentation used in drinking water treatment. The treatment process

involves the use of metal salts such as alum [A12(S04)3.14H20], and ferric chloride

(FeC13) to form complexes with colloidal particles suspended in water thus forming

aggregates and settling them out at the bottom of the source water (Butkus et al., 1998).

Another type of WTR, Ca-WTR is a by-product of the water softening industry where Ca

is used to remove water hardness by precipitation as insoluble Ca salts (O'Connor et al.,

2002). The composition of these residuals varies among water treatment plants depending

on the processes and chemicals used and also the composition of the source water being

treated. The purity of coagulants used also affects the residual quality. Elliott et al. (1990)

noted in a study that fractionation analysis of [A12(S04)3. 14H20] and FeC13 sludges,

found mean concentrations of all trace metals analyzed excepting Cd to be higher in the

FeC13 sludge. This was noted to be probably attributable to the fact that the FeC13 sludge

used by that treatment plant was a by-product of the steel industry. Most WTRs will

contain some fraction of either naturally occurring colloidal/particulate matter (clay, silt









etc.), insoluble metal oxide/hydroxide precipitates [e.g., Al(OH)3 Fe(OH)3] or some

activated carbon (ASCE, AWWA and EPA, 1996).

Water treatment residuals generally have tremendous capacity to adsorb significant

amounts of P because they are treated with [A12(S04)3.14H20] (Ippolito et al., 2003).

Alum hydrosolids not only reduce soluble P but they also have the added properties of

improving the physical properties and water holding capacity of plant growth media

(Peters and Basta, 1996). Water treatment residuals may be acceptable for use because

they do not have concentrated levels of toxic organic and pathogens (Elliott et al., 1990).

They also generally have lower concentrations of toxic metals such as Cd than biosolids,

which at times may be derived from effluents from industrial sources (Elliott et al., 1990;

Ippolito et al., 2002). Elliott et al. (1990) found the range in Cd and Zinc (Zn) contents of

water treatment sludges to be 10 and 35 percent respectively of the typical corresponding

mean values of municipal biosolids being land applied. O'Connor et al. (2002) also

analyzed Al, Ca and Fe WTRs and found that the concentrations of the heavy metals Cd,

Copper (Cu), Chromium (Cr), Nickel (Ni), Lead (Pb) and Zn were all much lower than

allowable levels by federal law.

Sandy Florida soils are typically acid, coarse textured and low in Ca with very little

clay (Anderson et al., 1995), with Al and Fe hydroxides being the solid phase

components responsible for the specific sorption ofP (Lu and O'Connor, 2001). The

amorphous hydroxides contained in WTRs may be of benefit to such coarse textured soils

by increasing their cation exchange capacity (CEC), (Ippolito et al., 2003). Although

alum WTR may appear suitable for these soils it should be noted that they have the

potential to bind P very strongly and this may result in a decrease in the quantity of plant









available phosphorus (Butkus et al., 1998; Ippolito et al., 2003). The potential problem of

Al toxicity to plants and excess soil acidity also exists with Al WTR use. Untreated

Al2(SO4) is a very soluble salt that releases toxic Al and produces acidity when dissolved

in water (Peters and Basta, 1996). Ann et al. (2000) suggested that the application of a

combination of alum and Ca based biosolids to soils with low pH buffering capacity,

could be very effective in soils that are subject to anaerobic environments. This is

necessary because, under the low pH conditions that may be created when Al is applied

to soils it is possible for the reduction of Fe3+ to Fe2+ releasing orthophosphate ions from

iron phosphate compounds. The simultaneous application of Al and Ca based biosolids

may have additional benefit as noted by Heil and Barbarick (1989), who suggested that if

acidic water treatment sludges were being applied to acidic soils, then they should be

limed to minimize the availability of toxic trace metals such as cadmium (Cd). Callahan

et al. (2002) noted that P in soils is generally most soluble at pH values within the range

of 6.0 and 7.0 so it would be ideal to have pH values outside that range to make P more

insoluble. On the higher end of the above-mentioned range, P is immobilized by the

precipitation of soluble calcium phosphates. Boruvka and Rechcigl (2003) referred to

work of previous authors who documented very little effect of Ca based amendments on

soil P retention because of the creation of induced soil negative charge and dissolution of

soil Fe and Al phosphates. Consideration should therefore be given to the thought that the

liming of soils containing Al and Fe phosphates may very well be expected to increase

phosphate solubility (Boruvka and Rechcigl, 2003).

The application of lime or some additional form of Ca based amendment may not

be necessary on the farms of animal operations in Florida which have sprayfields or other









forms of land application of animal manures. Animal manures are potential sources of

reducing soil acidity (O'Hallorans et al., 1997; Whalen et al., 2000; Wong et al., 1998)

and this pH buffering effect may last for a number of years. The short-term effects of

cattle manure additions on soil pH were observed in a study conducted by Whalen et al.

(2000) who observed an immediate increase of soil pH on addition of manures to soils

without any additional change in soil CEC. In that study, they found higher levels of

bicarbonate in the manure amended soils than in the unamended soils and concluded that

the bicarbonate contributed to the pH buffering capacity of the amended soils. However,

there was no evidence to support the idea that CaCO3 added to the diets of the animals

was responsible for this buffering capacity. In light of the above information, it may be

worth considering pre-incorporation of Al WTRs with some forms of animal manures

before application on land. The use of alum treated poultry litter has been mentioned in

the literature (Moore et al., 1995; Peters and Basta, 1996). This incorporation has the

added advantage of ensuring that any soluble unreacted Al salts that may be contained in

these residuals may be given a chance to fully react, reducing the risk of creating soil

acidity.

Soils located near barns and feedlots are sometimes high in Ca. This is because

limerock (Ca CO3) is often used to raise the foundations of these areas. The resulting pH

of these soils is generally high (>7.0) (Anderson et al., 1995; Ward et al., 1978) and the

retention of P is related more to the dominance of Ca in the system rather than Al and Fe

(Anderson et al., 1995; Cogger and Duxbury, 1984). It is generally thought that in these

high Ca soil systems, Ca compounds are the major components likely to control the

immobility of P (Ann et al., 2000; Lu and O'Connor, 2001) because at neutral pHs and









higher, Ca reacts with soluble P to form Ca-phosphates (Codling et al., 2002). Based on

the above mentioned information it would then follow that calcium-based boisolids (Lu

and O'Connor, 2001), or alternative calcium-based soil amendments are likely to be the

most effective in increasing the P retention capacity of soils around the barns and milking

parlors of these Florida animal operations. Soils in pastures or hay fields away from the

barns and feedlots are typically under low pH conditions with soluble Al and Fe being

more likely in controlling P retention than Ca.

However, there is some evidence that suggests a contrary explanation about the role

Ca plays in the immobilization of P in some high pH soil systems with high Ca levels.

The origination and form of the soil Ca source affects whether or not it controls P

immobility. Nair et al. (1995) in their work found that labile P leached from cattle

manures showed a positive relation primarily to the Ca and Magnesium (Mg) contents in

solution of the manures. This meant that though there were high P concentrations in the

soils they were highly unstable and susceptible to leaching. Cooperband and Good (2002)

supported the previously mentioned findings in their work which showed that while

calcium and magnesium phosphate minerals controlled P solubility in a poultry treated

soil, this was not the case in the dairy manure treated soil.














CHAPTER 3
MATERIALS AND METHODS

Soils

The soils used in the study were obtained from of two dairy animal operations,

Byrd Dairy (BD) and Oak Grove Dairy (OG) farms located in the Suwannee River Basin

in Suwannee County in North Central Florida. The soils have been used in the recent past

for the production of hay. Their nutrient status was however quite different as a result of

different fertilizer management histories. The OG hayfield had been previously fertilized

with dairy manure in the form of effluent and commercial inorganic fertilizers for a

number of years (approximately 10 to 15 years). The records of the quantities of effluent

applied to this farm could not be obtained, however, it was considered to be a heavily

manure-impacted soil. The soil at the BD hayfield received no applications of animal

manures prior to collection of samples. Fertilizer was applied to this field following

recommended practices for hay production. This was considered to be a relatively

manure-unimpacted soil.

Collection of bulk soil samples from the two locations was done by using a shovel

to remove clean cuts of soil from the Ap horizons to a depth of approximately 15 cm. The

soil samples were collected and placed into labeled drums. Soil from the roots of

remaining vegetation was gently shaken into the respective drums and the vegetation was

discarded. Three different collection points in each field were used for sample collection,

and the soil was then composite into a single sample.









All samples were brought to the laboratory and stored in a shed at room

temperature. They were placed on two cleaned pieces of plastic tarpaulin wraps and

placed in a greenhouse to air dry for two weeks. The air dried samples from the

respective locations were then manually screened by passing them through a sieve with 2

mm openings. After this was complete, samples were homogenized manually by

separately pouring out the screened contents of each drum on cleaned plastic tarpaulins

and mixing the contents thoroughly with a shovel. Screened homogenized soils were then

placed into their respective containers, sealed tightly and stored at room temperature for

later use.

Column Leaching Study

A laboratory column leaching study was conducted using a simple factorial

experimental design. The factors being the two soils mentioned above, three different P

sources (dairy storage pond effluent, broiler litter compost, triple superphosphate

fertilizer) and a control and two amendment tretaments (aluminum water treatment

residual (Al WTR) and a control). This block was again repeated four times. The

following combinations of 2 soils x 4 sources x 2 amendments x 4 replications gave a

total of 64 leaching columns. Fractionation studies were performed on soil columns at the

end of the leaching study.

Column Setup

The columns were built using 7.5 cm ID PVC piping cut at 30 cm lengths

(Figure 3.1). Each column had end caps on the bottom which were drilled, threaded and

fitted with spouts for proper drainage and collection of leachate. Pieces of woven

polypropylene sheets firmly placed at the end of each column before attachment of the

caps to reduce the loss of soil colloids with leaching. Soil columns were packed by









pouring and lightly compacting to a depth of 25 cm (leaving a 5 cm clearance for

simulated rainwater addition the soils). The P sources and amendments were applied and

thoroughly incorporated into the top 4 cm of the soil column (Figure 3-1). This depth (4

cm) was chosen to allow for a 1 cm buffer in anticipation of downward movement of

treatments, since the top 5 cm of each soil column was analyzed for P forms at the end of

the study. Columns were placed upright in wooden racks for the duration of the study.

Columns were leached nineteen times at approximately weekly intervals over a six month

period with artificial rainwater (adjusted to a pH of 5 similar to that of Florida rainfall) as

used by Wang et al. (1995) (Table 3-1). One pore volume (250 mL) of rainfall was used

to leach each column for each of the nineteen leaching events. The application of one

pore volume of rainfall to each column allowed for the collection of the desired adequate

volume of leachate needed for the various leachate analyses to be performed. Columns

were allowed to drain freely overnight after each leaching. Most of the rainfall applied

was leached from the columns and collected in 250 cm3 Nalgene bottles placed at the

drainage spouts below each column. The contents were then analyzed for a number of

variables.

Table 3-1. Chemical components of simulated rainwater
Chemical Formula Concentration
------- mg L -------
MgCl2.6H20 2.35
CaC12.H20 3.84
KC1 0.9
NaHCO3 2.09
NH4NO3 4.3









Phosphorus sources were applied to the upper 4 cm of soil at a blanket application

rate equivalent to 40 kilograms P per hectare (40 kg P ha-1). This rate was chosen because

it is a typical application rate used by commercial farmers. The Al WTR was applied at a

rate of 5% dry weight basis per gram of soil in the top 4 cm of soil (approximately 56

tons ha-1 for an A horizon).

The soil was moistened before being placed in the columns to avoid any effects of

hydrophobicity and preferential or disturbed flow during leaching. This was done by

applying approximately 12% (66 mL) of the total pore volume (volume occupied by air

and water) of DI water to a fixed mass of soil estimated to give a 25 cm soil column.

Soils were kept in polyethelene ZiplocTM bags, mixed and allowed to equilibrate 24

hours.

The poultry litter used in the study was obtained from the Black Hen poultry litter

composting facility in Oxford, Florida. The triple superphosphate fertilizer used in the

study was a commercially acquired pelletized fertilizer. The dairy storage pond effluent

was obtained from the North Florida Holstein Dairy operation in Florida. The stored

effluent contents of a manure storage pond were agitated and the pump used to pump the

effluent out to the spray-field was used to deliver a homogenous sample into black plastic

bags. Collected samples were cooled in ice chests until they arrived at the laboratory

where they were stored in a refrigerator at 40 C in a walk-in cooler until used. Well mixed

homogenous samples were analyzed for total P concentrations. Because of the low

concentration of solids in the dairy effluent, the required P concentration per column

needed a large effluent volume. The calculated volume (636 mL) required for each



















clearance for


21 cm depth of
remaining soil colunn


Figure 3-1. Diagram of leaching column containing soil and treatment









column was applied in small increments (60 mL each) to clean, labeled plastic weighing

containers containing the mass of soil (250 g) estimated to represent the top 4 cm of the

soil columns. The soil was air-dried before adding subsequent increments. This was done

until the total calculated dairy effluent volume per column required was applied.

Analytical Procedures

Soil Analysis

Total carbon (TC) and total nitrogen (TN) contents of the soils were determined by

combustion at 1010 C in a Carlo Erba NA-1500 CNS Analyzer (Carlo-Erba Instruments,

Rodano Milan, Italy). The pH was measured on the supernatant of 1:2 soil to solution

ratio that was stirred and allowed to sit for 30 minutes using an Orion pH electrode

(Orion Research Inc. Boston, MA). Mehlich-1 extractable Al, Ca, Fe, Mg and P were

determined on air-dried samples using a 1:4 soil to DA (0.0125 M H2S04 and 0.05 M

HC1) ratio shaken for 5 minutes (Mehlich 1953). Water soluble P (WSP) was determined

by analyzing the extracts obtained from samples by shaking a 1:10 soil (g) water (cm3)

combination for one hour and then filtering contents through 0.45[jm filter paper. The

filtrate was analyzed for P using EPA Method 365.1 (USEPA 1993).

P Source/ Amendment Analysis

Total phosphorus concentration determinations were made for all P sources.

Homogenous samples of poultry litter weighing 0.4 g and of TSP weighing 0.09 g were

digested in Kjeldahl Reagent using a modified method of Jones et al. (1991). The

resulting digests were analyzed for P using EPA Method 365.1 (USEPA 1993).

Homogenous samples of the liquid dairy storage pond effluent were digested in Kjeldahl

reagent using a 5:1 sample to reagent ratio according to EPA Method 365.1 (USEPA

1993).









Leachate Analysis

Leachates samples were analyzed for pH, electrical conductivity (EC), soluble

reactive phosphorus (SRP) and TP. Total phosphorus was determined using EPA Method

365.1 (USEPA 1993). Electrical conductivity and pH were measured on the same day of

leachate collection. An Orion pH electrode (Orion Research Inc. Boston, MA) was used

to measure pH.

The measured pH values of the leachates collected during the study were converted

to anti-logarithmic values (hydronium ion (H ) concentrations) before being statistically

analyzed.

Water Treatment Residual Analysis

Analysis and characterization of the Al WTR used in the study was done by

O'Connor and Elliot (2000).

Soil Fractionation

Fractionation of the soil samples taken at different depth increments was performed

according to a modified version of the procedure used by Hedley et al. (1982). Soil

columns were carefully removed and split into three depth increments (0-5 cm, 5-15 cm

and 15-25 cm) from the top, respectively.

A flow chart summarizing the fractionation scheme is shown in Figure 3-2. A 1:50

soil to solution ratio (0.5 g soil + 25mL of 0.01 M CaC12, 0.5 M NaHCO3, 0.1M NaOH,

and 1.0 M HC1 respectively) was used for all extractions. Air-dried 0.5 g samples of soil

from each depth increment (0-5cm, 5-15 cm, 15-25 cm) of the selected soil columns were

used for extraction in the fractionation study. Extractants were applied to samples and

shaken for 16 hours, after which the supernatant removed and centrifuged at 10,000 g for









ten minutes and vacuum filtered through 0.45am filter paper. The supernatant was stored

in 20 mL scintillation vials at 40 C until analyses were performed for Pi.

The 0.5 M NaHCO3 and the 0.1M NaOH supernatants were analyzed for both Pi

and Po. Sample preparation for Pi analysis was done by adding 5 drops of ultra pure

sulfuric acid (H2SO4) to 5 mL aliquots of each extractant (on the day of analysis) and

centrifuging at 8,000g for eight minutes. The acid was added to precipitate any organic

matter present in the sample. The Po of the supernatants was determined by the respective

differences between theTP and Pi quantities of the supernatants (i.e. Po = TP Pi). The TP

of the 0.5 M NaHCO3 and the 0.1M NaOH supernatants was determined by adding 1 mL

of 5M H2SO4 + 0.3g potassium persulfate (K2S208) to 5 mL aliquots of each supernatant

in digestion tubes and digesting the samples. Samples were digested by placing them on a

digestion block at 125-1500 C for 2-3 hours (until 0.5 mL of solution remained), then

covering the digestion tubes with glass digestion tube caps and increasing the temperature

to 3800 C for 3-4 hours. At the end of digestion, 10 mL of DI water was added to the

cooled samples and they were vortexed to ensure complete dissolution of salts. The

solutions were then stored in 20 mL scintillation vials at room temperature until they

were analysed.

The Residual P determination was done according to the method used by

(Anderson, 1976). After removal of the supernatant of the final extractant (1.0 M HC1)

from the soil samples, the remaining soil and solution were transferred to 50 mL beakers

by carefully washing the container containing the soil (0.5 g) with DI water to dislodge

soil particles. Samples were allowed to evaporate on a hotplate until only dry soil

remained. Dried samples were ashed in 50 mL beakers at 5500 C in a muffle furnace for 4









to 5 hours, after which 20 ml of 6 M HC1 was added to the samples which were then

placed on a hot plate (Anderson, 1976). Dried samples were removed from the hotplate

and 5 mL of 2.5 M HC1 was added to them before the beaker contents were rinced with

DI water and placed in 25 mL volumetric flasks. The contents of these flasks were

analyzed for the residual P.



Statistical Analyses

All statistical analyses were performed using SAS analytical software package,

(2001) SAS Institute Inc., Cary, NC, USA. Analyses of variance for the data obtained

from the leachate and the fractionation studies were performed using a general linear

model procedure (GLM). A mixed procedure repeated depth analysis was also performed

on the fractionation data obtained from the three depths.











Soil

0.5 g





Soil + 25 mL 0.01 M CaCl2 Shake
16h; centrifuge 10 min. at 10,000 g;
filter 0.45gm. Decant supernatant
into 20 mL scintillation vials. Store
at 40 C until analysis.


Soil + 25 mL 0.5 M NaHCO3
Shake 16h; centrifuge 10 min. at
10,000 g; filter 0.45 pm. Decant
supernatant into 20 mL scintillation
vials. Store at 40 C until analysis.



Soil + 25 mL 0.1 NaOH Shake
16h; centrifuge 10 min. at 10,000 g;
filter 0.45 pm. Decant supernatant
into 20 mL scintillation vials. Store
at 40 C until analysis.



Soil + 25 mL 1 M HC1 Shake 16h;
centrifuge 10 min. at 10,000 g;
filter 0.45 pm. Decant supernatant
into 20 mL scintillation vials. Store
at 40 C until analysis.


I Labile P












SAl/Fe bound P







SCa/Mg bound P


Decant remaining soil + HC1 into
50 mL beakers. Using a hotplate Recalcitrant P
allow solution to evaporate slowly
until only dry soil remains. Ash
then digest according to Anderson
(1976).


Figure 3-2. Schematic of the modified fractionation procedure adopted from Hedley et al.
(1982).


TP















CHAPTER 4
RESULTS AND DISCUSSION

Soil Characterization

Prior to addition of treatments and amendments to the soils, the Mehlich-1

extractable Al concentrations in the Ap horizons of the two soils were not greatly

different with the values being 153 mg kg-1 and 171 mg kg-1 for the Byrd Dairy (BD) and

Oak Grove Dairy (OG) soils, respectively (Table 4-1). The BD soil also had Mehlich-1

Fe concentrations three times greater than the OG soil which had a concentration of 14

mg kg-1. The BD soil had a higher percentage C (1.59%) than the OG soil (0.99 %). The

water soluble phosphorus concentration of the BD soil (1.32 mg kg-1) was considerably

less than that of the OG soil (10.32 mg kg-1) being almost ten times lower.

Given the above mentioned information about the soils and their respective

management histories, it is reasonable to say that the OG soil was more likely to have a

reduced P sorbing capacity and hence would be prone to leaching larger amounts of labile

P than the BD soil when additional sources of P were added.

Table 4-1. Selected Chemical Properties of the Ap Horizons of the Byrd Dairy and Oak
Grove Dairy soils (n = 6).
Location pH TCt TNt SP ---------------- Mehlich-1 --------------
Location pH TCt TNt WSP) Mehlch-
Al Ca Mg Fe
------- % -------- --------------------------- mg kg ----------
Byrd Dairy 5.74 Mean 1.59 0.09 1.32 153 351 35 45
Std.dev. 0.43 0.02 0.84 86 201 19 24
Oak Grove
6.50 Mean 0.99 0.05 10.32 171 635 69 14
Dairy
Std.dev. 0.22 0.04 2.63 30 428 21 3
t Total carbon (TC) and total nitrogen (TN)
3 Water Soluble Phosphorus









Amendment Characterization

Elemental analysis of the WTR previously reported by O'Connor et al. (2002)

showed that it was dominated by Al (89 g kg-1) (Table 4-2) with approximately 80% of

the total Al being in an amorphous form. The amorphous P is represented by the amount

of oxalate extractable P (Table 4-3). Though the analytical results show a high level of

organic matter in the WTR (24%), organic P only accounted for 3% of the total amount

of P (2.8 g kg-1) contained in the WTR.

The WTR had a high P sorbing capacity as was seen by the low phosphorus

saturation index (PSI) value calculated in Table 4-3 (O'Connor et al., 2002). The PSI is

used as semi-quantitative measure of a soil's ability to sorb P low phosphorus saturation

index (O'Connor et al., 2002; Schoumans, 2000).

Table 4-2. Selected properties of the Al-WTR used in the study (O'Connor and Elliot,
2000).
Form Total Elemental S s Ot
Form Solids OMf pH
C N C:N Fe Al Ca Mg P
-- mg kg -- -------------- g kg ------------ ------ % -----
Alum 19.13 0.73 26.21 3.7 89.1 15.3 0.12 2.79 58.5 24.1 5.25
T Organic Matter

Table 4-3. Phosphorus fractions, oxalate extractable P, Fe, and Al and P sorbing capacity
of the Al-WTR (O'Connor and Elliot, 2000).
Org. Pt Sequentially Extracted P M Oxalate Extractable S
KC1 NaOH HC1 Sum P Fe Al
------------------------------------ mg kg----------------------
3 <0.41 2315 473.7 2788 4.35 2664 1655 71,972 0.032
? Organic P determined by loss on ignition
Less than Method Detection Limit (0.41 mg kg 1)
Phosphorus Saturation Index = oxalate P/oxalate Fe + Al (in moles)

Leachate Characterization

pH

Statistical analysis of the hydronium ion (H ) concentrations of the leachates

collected from the BD soil showed that P source, amendment treatment (i.e. Al-WTR









added vs no Al-WTR) and P source*amendment interaction had no significant (P =0.05)

effects on the pH at the beginning of the study (Table 4-4).

Table 4-4. p values for hydronium ion concentrations of the Byrd Dairy and Oak Grove
soil column leachates for the 1st leaching event.
Soil P source Amendment P source Amendment
Byrd Dairy 0.5840 0.2197 0.6784
Oak Grove 0.6384 0.8609 0.7571


At the initiation of the leaching process, pH values of the leachates from the BD

soil were relatively low, averaging 3.9 for the amended and unamended P source

treatments (Table 4-5). There were no significant (P =0.05) differences in pH values

observed for the main interactions for the first set of leachates collected.

Table 4-5. Average pH values of the Byrd Dairy soil column leachates for the 1st
leaching event.
Treatment Amended Unamended
Control 3.9 3.9
Dairy storage pond effluent 3.9 3.9
Inorganic fertilizer 3.9 3.9
Broiler litter compost 3.9 3.9

As the leaching progressed, the pH values of all leachates began to increase (Figure

4-1). At the completion of about the fourth leaching event, a trend of separation of pH

values began to appear. The pH levels of the leachates collected from the columns treated

with the dairy storage pond effluent began to get consistently higher than those of the

other P sources for both the amended and unamended soil treatments (Figure 4-1).

The statistical analysis of the H concentrations at the end of the nineteenth

leaching event for the BD soil produced ap value of 0.0221 for the amendment

interaction which meant that there was a significant (P =0.05) amendment effect on the

soil pH (Table 4-6).









Table 4-6. p values for Hydronium ion concentrations of the Byrd Dairy and Oak Grove
soil column leachates for the 19th leaching event.
Soil P source Amendment P source Amendment
Byrd Dairy 0.1063 0.0221 0.2535
Oak Grove 0.7625 0.3110 0.8006

The average pH values of all treatments increased by at least 1.5 units ranging from

5.4 7.4 units. The dairy storage pond effluent column leachates were the highest with an

average pH of 7.4 for both amended and unamended treatments (Table 4-7). The higher

pH values of the dairy storage pond effluent treated column leachates is related to the Ca

and Mg concentrations in the manures excreted by the dairy cattle. Nair et al., 1995,

noted that the Ca and Mg supplements in the feed of dairy cattle results in high levels of

these metals in the manure. Increased levels of these metals in soils treated with dairy

storage pond effluents causes the pH of rainfall that leaches through these soils to

increase.

Table 4-7. Average pH values of the Byrd Dairy soil column leachates for the 19th
leaching event.
Treatment Amended Unamended
Control 5.4 6.3
Dairy storage pond effluent 7.4 7.4
Inorganic fertilizer 6.1 6.7
Broiler litter compost 5.6 6.7

The Al-WTR had an effect on the pH values leachates of the remaining P source

treatments and the control. The WTR amended column leachates had lower pH values

than the unamended column leachates (Table 4-7). The decrease in the pH values of the

amended column leachates is most likely due to hydrolysis of Al compounds causing the

release of H+ ions.

There were no significant (P =0.05)p values obtained in statistical analyses of both the

first and last leaching events for OG soil (Tables 4-4 & 4-6). This means that the main














9.0
8.5
8.0
7.5
7.0
6.5
S6.0
5.5
5.0
4.5
4.0
3.5
3.0


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost


9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
S Control -- Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost


Figure 4-1. Trends in pH changes observed for theByrd Dairy soil. (A) Amended column
leachates. (B) Unamended column leachates.









interactions (P source, amendment, P source*amendment) had no effect on the overall

mean pH for these events.

There were no distinct trends of separation of pH values for leachates collected

from amended and unamended treatments for the OG soil (Figure 4-2). At the initiation

of the leaching, the average leachate pH values ranged between 7.1 and 7.2 (Table 4-8).

Table 4-8. Average pH values of the Oak Grove soil column leachates for the 1st leaching
event.
Treatment Amended Unamended
Control 7.2 7.2
Dairy storage pond effluent 7.2 7.2
Inorganic fertilizer 7.1 7.2
Broiler litter compost 7.1 7.1


At the end of the second leaching, pH values increased, being in the region of 8.0

(Figure 4-2). These increased pH values were sustained throughout successive leaching

events. At the end of the nineteenth leaching, the average pH values showed a

approximately one pH unit increase over the average values of event one, ranging

between 8.2 8.3 for all leachates (Table 4-9).

Table 4-9. Average pH values of the Oak Grove soil column leachates for the 19th
leaching event.
Treatment Amended Unamended
Control 8.2 8.2
Dairy storage pond effluent 8.2 8.2
Inorganic fertilizer 8.3 8.2
Broiler litter compost 8.2 8.2

The effect of the high Ca and Mg concentrations in Dairy storage pond effluents on soil

leachate pH was also evident in the trends observed for the OG soil. The fact that the

leachate pH values of dairy storage pond effluent treated columns for the OG soil were

not higher than other treatment values, did not mean that there was no effect of dairy

storage pond effluent treatments on the
















9.0
8.5
8.0
7.5
7.0
6.5
S 6.0
5.5
5.0
4.5
4.0
3.5
3.0


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent

Triple superphosphate fertilizer '- Broiler litter compost


B)
9.0
8.5
8.0
7.5
7.0
6.5
S 6.0
5.5
5.0
4.5
4.0
3.5
3.0


1 2 3 4 5


6 7 8 9 10 11
Leaching Event


12 13 14 15 16 17 18 19


Control -- Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost





Figure 4-2. Trends in pH changes observed for the Oak Grove soil. (A) Amended column
leachates. (B) Unamended column leachates.









OG soil. The high pH values for all the OG leachates were due to the previous history of

land application of dairy storage pond effluent to the soil for a number of years. The soil

had almost two times the concentrations of Ca and Mg contained in the BD soil (Table 4-

1). This resulted in high pH values for all leachates from this soil and thus masking any

effects the different chemical characteristics of the respective applied P sources would

have on leachate pH values.

Electrical Conductivity

A sharp decrease in EC values was observed between the first and third sets of

leachates collected (Figures 4-3 & 4-4). The overall EC values for the minimally manure

impacted BD soil were lower than the highly impacted OG soil. At the beginning of the

study, EC values for the BD soil ranged from 3225 3895 [tS cm-1 while those of the OG

soil were in the range 3995 5263 [tS cm-1. At the end of the study, BD values ranged

from 65 108 [tS cm-1 with those of OG ranging between 292 393 [tS cm1.

At the initiation of leaching, the EC values of the leachates collected from BD soils

were high, being within the ranges of, 3413 3895 [tS cm-1 for the amended treatments

and 3255 3788 [tS cm-1 for the unamended treatments. The values then gradually

decreased with successive leachings until the completion of the study. The final EC

values were in the ranges of 72 107 [tS cm-1 for the amended and 65 108 [tS cm-1 for

the unamended treatments.

The above decreasing trends in the EC values for leachates collected from the OG

soil were similar to those observed in the BD soil leachates (Figures 4-3 & 4-4). The

initial amended and unamended EC value ranges were 4183 5263 and 3995 4840 [tS

cm-1 respectively. The final EC value ranges of the respective amendments were 338 -

350 [tS cm-1 and 292 353 [tS cm1.














6000

o 5000
CA

4000

- 3000


. 2000

1000

0


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost


6000

5000

4000

3000

2000


1000


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent

Triple superphosphatefertilizer Broiler litter compost


Figure 4-3. Average electrical conductivity values for leachates collected from columns
containing different P source treatments for the Byrd Dairy soil. (A) Amended
column leachates. (B) Unamended column leachates.














6000


5000


4000


3000


2000


1000


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost


6000


5000


4000


3000


2000


1000


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
-*- Control -- Dairy storage pond effluent

Triple superphosphate fertilizer Broiler litter compost





Figure 4-4. Average electrical conductivity values for leachates collected from columns
containing different P source treatments for the Oak Grove soil. (A) Amended
column leachates. (B) Unamended column leachates.









The first seven sets of leachates collected from the BD columns treated with dairy

storage pond effluent had significantly (P = 0.05) higher EC values than the other

leachates of the remaining P sources (Figure 4-3). This was consistent for both amended

and unamended treatments. The dairy storage pond effluent treated column leachates for

the OG soil, showed a similarly higher trend than the remaining leachates of the columns

with different P source treatments leachates (Figure 4-4). This trend was however not

observed after the third leaching event. There was no other trend of distinction of the EC

values of the leachates of columns with remaining treatments.

Electrical conductivity of a soil or soil solution is a measure of its total salt

concentration. The general inorganic dissolved solutes that contribute to the EC of a soil

are Na Mg2+, Ca2+, K, C1, S042-, HC03- and C032- (Rhoades 1993). A high EC value

can therefore be interpreted as a high salt concentration and vice versa. Among the

leachates, the initially higher EC values of the effluent treated leachates is because the

dairy storage pond effluent contained more soluble salts than the other treatments, which

were transported with the leaching solution applied to these columns. The relatively high

EC values of the leachates collected from the first three leachings for both soils can be

explained by a mechanism described by Jackson (1958), which causes soil drying in arid

and semi arid soils and has the effect of increasing the soluble salt content at the soil

surface. As water is removed by evaporation the dissolved salts are drawn out and

deposited on the soil surface. The soils were air dried prior to leaching in a greenhouse

and a similar process of dehydration of the soil salts occurred on evaporation of the soil

moisture. Leaching of these dried soils caused the salts to re-dissolve into the leachates

resulting in very high EC values for the first three sets of leachates.









According to Jackson (1958), fertilization of soils may lead to a build up of excess

salts in that soil. This explains why the OG soils because of their previous fertilization

history, had higher EC values than the BD soil which was minimally impacted by

fertilization. Among the respective treatments, the higher EC values of the dairy storage

pond effluent treatments would most likely be associated with the high amounts of

leachable Ca, K, Na and Mg salts typically contained in them.

Phosphorus

The OG soil leached significantly greater amounts of P than the BD soil among all

the treatments and amendments (Table 4-10). On average, there was a five-fold

difference in the overall average P leached between both soils (Figure 4-5). Previous

history of the OG soil involved dairy manure application for over ten years may have

contributed to this observation. The soil therefore had high background levels of labile P

as noted in the control, which was most likely associated with unstable and readily

leached Ca and Mg compounds contained in the manure (Nair et al., 1995). This meant

that the entire soil column had high P concentrations, some of which was dissolved in the

simulated rainwater used to leach the columns. There was no significant difference

between the cumulative SRP and the TP in the collected the leachates obtained

throughout the duration the study. This observation was evident for all P sources and

amendments for the respective soils (Table 4-11). This indicated that there was not a

great amount of soluble organic P leached from both soils used in the study.

The Al-WTR proved to be effective at retaining soil SRP. A comparison of

amended and unamended treatments of the BD soil showed that significantly (P = 0.05)

less SRP was leached from the amended treatments (3.9 5.3 mg P) for each P source








42




(A)

40

35

g 30

25

S20

E 15

10

5

0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event

Byrd Oak Grove


(B)
40

35

S30

25

20

15

10

5

0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Byrd Oak Grove





Figure 4-5. Overall average masses of phosphorus leached from the Byrd Dairy and the
Oak Grove Dairy soils. (A) Soluble reactive phosphorus. (B) Total
phosphorus.










Table 4-10. SRP amounts leached from BD and OG soils over 19 leaching events.
SRP Control Dairy Fertilizer Broiler litter compost
--------------------------------mg P------------------------------
Am NAm Am NAm Am NAm Am NAm
BDt 3.90A'c 4.80Ab 5.30Bab 6.50Aa 3.90Bc 5.60Aab 4.00Bc 6.00Aab
OG 21.42AK 23.58Abc 20.93Bc 26.24Aab 21.62Bc 27.69Aa 20.98Bc 24.93Aab



Table 4-11. TP amounts leached from BD and OG soils over 19 leaching events.
TP Control Dairy Fertilizer Broiler litter compost
--------------------------------mg P------------------------------
Am NAm Am NAm Am NAm Am NAm
BD 3.85B 5.10A 7.39Bb 9.00Aa 4.21B 6.48Ab 4.22B 6.61Ab
OG 22.90AK 24.67Abc 21.96Bc 26.63Aab 23.03Bc 29.01Aa 21.84Bc 26.91Aab
f Means within each soil followed by the same letter are not significantly different LSD=o 05o
8 Capital letters represent differences for amended and unamended treatments for each P source
Superscripted lower case letters represent differences among all treatments
Amended
Unamended

excepting the control, were there was no difference between the amended and unamended

treatments (4.8 6.5 mg P) (Table 4-10). The fact that there was no difference between

the amount of P leached between the amended and unamended control treatments shows

that there was no effect of addition of the WTR on increasing the SRP leached from the

soils.

Among the amended BD treatments, the amended dairy storage pond effluent

leached a significantly greater quantity of SRP (5.30 mg P) than the other amended

treatments, which were not statistically (P = 0.05) different from each other. The WTR

was effective at retaining the P leached from the fertilizer and broiler litter compost litter

treatments, to the same amount as the control treatment. This shows that the WTR had

sufficient P retention capacity to retain the added P from the applied sources with the

exception of the dairy storage pond effluents. The reduced effectiveness of the WTR at

reducing the P leached from the dairy storage pond effluent treatment was most likely

related to one or both of two factors 1) the P was mostly as SRP when added to the soil 2)









the existence of some soluble organic carbon in the dairy storage pond effluent. The

effluent was in a very liquid form containing few suspended solids. This means that the

majority of the P was in a water-soluble form and, upon rewetting the soil during

leaching the P may have easily been solubilized and moved vertically with the leaching

solution.

Among the unamended BD columns, the dairy storage pond effluent leached the

greatest mass of P with the remaining treatments being in the order fertilizer > broiler

litter compost litter. The fertilizer was expected to leach more SRP than the broiler litter

compost because it is designed to be a source of readily available plant P. The dairy

storage pond effluent was the only treatment to leach a significantly higher amount of

SRP than the control treatment. This showed that the dairy storage pond effluent P was in

a more leachable from.

For the highly manure impacted OG soil, a comparison of the leached SRP between

amended and unamended soil treatments (Table 4-10) revealed a somewhat similar trend

to that of the BD soil. Among all treatments with the exception of the control soil

treatments, the difference between the respective amended and unamended treatments for

each P source was significant. There was no difference between the SRP leached between

the amended and unamended controls. This again showed that the P content of the WTR

was not being released when the soils were leached, because of the high affinity of the Al

in the WTR for P and the high P sorbing capacity of the WTR.

Among the amended OG treatments, the effectiveness of the WTR on the leachable

P in the layer of application was once more evident (Table 4-10). Though the soil was









heavily manure-impacted, an effect of the WTR on the SRP leached was observed. There

was no difference in the quantity of SRP leached from the various P sources.

Among the unamended treatments, SRP amounts leached from soils were in the

order fertilizer > dairy storage pond effluent > broiler litter compost litter, though

differences in SRP leached among these sources were not significant (P= 0.05). The

fertilizer treatment was the only treatment which leached a significantly greater quantity

of SRP than the control. The high levels of SRP in this soil prior to the study may have

masked the effects of the differences between the amounts of SRP, which existed among

applied P sources in the overall leachate P from the soil columns.

Though the nutrient status of the soils used in the study was different, the addition

of sources of P at a rate equivalent to 40 kg P/ha. (18mg P/column) to the soils had

significant (P =0.05) effects on the SRP leached from the respective soils. This was seen

in the significant differences between control and P source treatments for amended (OG)

and unamended (BD and OG) soils (Table 4-10).

The effect of adding P to a previously manure-impacted soil was also evident

when the overall differences in leached SRP (excluding controls) from amended and

unamended treatments within each soil were compared. The BD soil had an average

difference of 1.6 mg P while the OG, with an average difference of 5.1 mg P, was over

three times that of the BD soil.

Fractionation

Statistical analysis of the sequential fractionation data obtained from the BD soil

showed significant values (P = 0.05) for all main effects within at least one P fraction

(Table 4-12). The HC1 P fraction was the only fraction that did not have any significant

values. A closer analysis of the mean P values in Table 4-13 revealed in general no










consistent trends of major differences or activity between the amended and unamended

soil fractions in the 5-15 cm and the 15-25 cm depth increments in the leaching columns

from top down respectively. The data for the soil samples from the 0-5 cm layer showed

some differences both between amendments and also among depths, being different from

the other two depths at times. This observation was consistent with the fact that the depth

of incorporation of all P sources and amendments was within the top 5 cm. The

sequential data from the 0-5 cm layer was hence used to analyze the effect of the WTR

on soil P forms.

Table 4-12. p values for main effects and interactions for the BD soil. (P = 0.05).
P fraction Depth P source Amendment P source *
Depth
LabileP <0.0001 0.0673 0.0091 <0.0001
NaOH P, <0.0001 0.0903 0.0003 <0.0001
NaOH Po 0.0007 0.6757 0.0210 0.0001
HC1P 0.2904 0.4849 0.2214 0.4300
Residual P 0.0114 0.0030 0.0038 0.0006
Sum Pf <0.0001 0.5869 <0.0001 0.0729
P fractionY Amendment Depth P source *Amendment P source Amendment* Depth
Labile P 0.0178 0.0759 <0.0001
NaOH P, <0.0001 0.0480 <0.0011
NaOH Po 0.0031 0.0058 0.0015
HC1P 0.5613 0.3700 0.4303
Residual P 0.0135 0.2540 0.0005
Sum Pf <0.0001 0.7757 0.0392
T Sum of P fractions
Labile P = (CaC12 P + NaOH P, + NaOH Po)

Data for the labile fraction ofP (LP) for the 0-5 cm depth in the BD soil showed no

significant differences (P = 0.05) between amended and unamended columns of the

respective P sources except for the dairy storage pond effluent treated columns (Table 4-

13). However, an increasing trend of NaOH Pi in amended over unamended treatments

was observed. The high binding capacity of the Al-WTR most likely was responsible for

this increase in NaOH Pi by providing additional surface sites for the adsorption of labile

P in the soil. Though the P may have just been physically sorbed and not chemically,









there was a retention effect seen. The amended dairy storage pond effluent treatment

contained significantly less LP than the unamended treatments (Table 4-13). This was

due to the highly leachable constituents of the effluent which may have resulted in more

of the P being quickly leached below the depth of amendment with the rainfall.

The NaOH Pi fraction was the fraction which showed the major effect of the WTR

on soil labile P. Among all P source treatments with the exception of the control, the

amount of NaOH Pi contained in the amended treatments was at least three times greater

than the unamended treatments (Table 4-13). This shows that the Al contained in the

WTR was very effective at completing soil P, retaining it as the strongly held more

resistant NaOH extractable Pi fraction.

The large differences between the amended and unamended NaOH Pi amounts may

be partly explained by the fact that LP which would normally be leached to lower soil

depths during rainfall was strongly and quickly completed by the Al oxide sites of the

A1-WTR.

The differences in leached LP were however too small to explain entirely the huge

differences observed for the NaOH Pi fraction. Another factor that may have contributed

to this huge P difference may be the fact that the WTR was a by-product of a drinking

water treatment plant thus contributing an additional source of P to this fraction.

Additional to the conversion of the LP fraction of both soils and sources to NaOH

Pi, the WTR may have converted the other P fractions in the added P sources to the

strongly held Al and Fe bound Pi fraction. The control treatments were not statistically

different, though the amended treatment contained more P than the unamended. For the













Table 4-13. Sequential data for amounts of P ([ag P/g soil) in the soil P fractions in the Byrd Dairy soil.
Control Dairy effluent Fertilizer Broiler litter comnost
Labile P Am NAm" Am NAm Am NAm Am NAm
0-5 cm 37.5 AB a 34.1 A 33.0 Aa 47.9 B 50.0 Cd 44.5B C b 47.0 B bc 42.9 B b
5-15 cm 39.1 B 41.2 BC 33.0C A 39.3 AB 35.8 A 40.5 AB 35.0 AB 43.3 B
15-25 cm 44.5 C 42.8 BC 45.0 B 43.5 B 39.8 AB 50.0 C 36.9 AB 41.8 B
NaOH P
0-5cm 28.0Aa 19.0Aa 115.0 B b 34.5Aa 113.5 B b 21.0 Aa 120.5 Bb 28.0Aa
5-15 cm 25.0 A 28.5 A 20.0 A 18.0 A 21.5 A 16.5 A 21.5 A 19.5 A
15-25 cm 28.0 A 30.5 A 18.0 A 24.5 A 17.0 A 32.0 A 18.5 A 23.0 A
NaOH Po
0-5 cm 102.5 C c 35.5 AB a 43.5 A ab 47.5 Aab 50.5 A b 49.5 A ab 50.5 A b 46.0 A ab
5-15 cm 39.0 B 24.5 A 46.5 A 45.0 A 45.0 A 45.0 A 51.5 A 48.5 A
15-25 cm 39.5 B 32.5 AB 45.0 A 46.5 A 42.5 A 49.0 A 48.0 A 51.0 A
HCI P
0-5cm 3.5 Aa 1.5 Aa 3.0 Aa 2.5 Aa 5.5 Aa 3.0Aa 4.0 Aa 3.5 Aa
5-15 cm 0.5 A 1.0 A 0.5 A 0.5 A 1.0 A 0.5 A 0.5 A 0.0 A
15-25 cm 18.0 B 0.5 A 0.5 A 1.0 A 0.5 A 1.0 A 0.5 A 1.0 A
Residual P
0-5cm 35.0 Ac 24.0 A bc 11.0Aa 12.5 Aab 11.0Aa 7.0 Aa 15.0 A b 9.5 Aa
5-15 cm 23.0 A 22.0 A 53.5 B 12.0 A 15.5 A 2.0 A 16.0 A 13.0 A
15-25 cm 24.0 A 21.0 A 17.0 A 12.0 A 14.5 A 1.0 A 13.5 A 11.0 A
Sum P
0-5 cm 206.5 C b 115.5 Aa 206.0 Cb 145.5 B a 230.0 B bc 125.0 Aa 237.0 B c 130.5 Aa
5-15 cm 127.5 AB 117.0 A 154.0 B 114.5 A 119.0 A 103.5 A 124.5 A 124.5 A
15-25 cm 155.0 B 127.5 A 126.0 AB 127.0 A 115.0 A 133.5 A 118.5 A 128.0 A
t Values with the same capital letters represent least squares means within each P source that are significant at the a = 0.05 level using pooled variance
comparative estimates in an appropriate t-statistic.
Values with the same lower case superscripted letters represent least squares means among means in the 0-5 cm soil column depth that are significant at the a =
0.05 level using pooled variance comparitive estimates in an appropriate t-statistic.
Amended
Unamended









NaOH soil P fraction, the amended treatments contained significantly higher amounts of

P than unamended treatments. However, whereas the major differences for the treatments

with added sources of P were seen in the NaOH Pi fraction, the difference for the control

was evident in the NaOH Po fraction.

The differences in P amounts between the amended and unamended sources for the

more resistant Al and Fe bound NaOH Po fraction were small and not statistically

significant for all P sources except for the control where the amended treatment was more

than twice the amount of that in the unamended treatments (Table 4-13).

There was no effect of P source and WTR on the more resistant residual and HCI

soil P fractions (Table 4-13) as the differences were between amended and unamended

treatments were not significant. These fractions tend not to be easily changed and usually

changes are seen over long periods of time.

There was a significant difference between the sum of the P fractions in the

amended and unamended soils for all P sources (Table 4-13). This means that the P

retention capacity of the WTR amended soils was greatly enhanced by the use of the

WTR.

Statistical analysis of the sequential fractionation data obtained from the OG soil

shows that there were significant interactions of the main effects (Table 4-14). The LP,

NaOH Pi and NaOH Po extractable P fractions were most notable with significant p

values for most interactions. The interactions of the main effects for the HC1 P, residual P

and were not significant (P = 0.05). The amendment main effect showed a significant (P

= 0.05)p value for the combined total of the P fractions (sum P) (Table 4-14).










Table 4-14. p values for main effects and interactions for the OG soil (P=0.05).
P fraction Depth P source Amendment P source *
Depth
Labile Pf 0.0001 0.0119 <0.0001 <0.0001
NaOH P, 0.0001 <0.0001 <0.0001 <0.0001
NaOH Po <0.0001 <0.0001 0.449 <0.0001
HC1P 0.9983 0.1683 0.4231 0.1574
Residual P 0.4924 0.0042 0.4304 0.1114
Sum Pf 0.1880 0.3535 0.0074 0.4030
P fraction Amendment Depth P source *Amendment P source Amendment* Depth
Labile P <0.0001 0.0244 0.0001
NaOH P, <0.0001 0.0002 0.0001
NaOH Po 0.0002 0.550 0.0001
HC1P 0.0305 0.1779 0.5932
Residual P 0.2195 0.0376 0.8171
Sum Pf 0.0058 0.1312 0.5926
T Sum of P fractions
g Labile P = (CaC12 P + NaOH P, + NaOH Po)

The LP fractions in the 0-5 cm depths of the amended OG soil treatments were

significantly less than the unamended ones for all sources. This means that the addition of

the WTR decreased the amount of soil LP. Table 4-15 shows that there seemed to be a

depth effect of LP in the columns, i.e. LP increased with depth. This observation was

consistent for both amended and unamended P sources. This demonstrates the effect

rainfall or leaching of P on a heavily P loaded soil with limited P fixing capacity to which

labile sources of P have been added.

The effects of the Al-WTR on the NaOH Pi fraction were evident only in the 0-5

cm soil depths (Table 4-15). This was expected since the amendment was applied at this

depth. As in the case of the BD soil, all amended P sources with the exception of the

control had significantly greater amounts of NaOH Pi than the unamended treatments at

this depth. The largest difference of 153 tg P/ g soil was observed for the fertilizer

treatment which was expected to have a high amount of available P. The amended and

unamended control treatments were not significantly different. This observation was

similar to the control of the BD NaOH Pi soil fraction.









As in the case of the BD soil, only the control NaOH Po fraction showed any

significant difference (121 [tg P/ g soil) between amended and unamended treatments.

This difference of 121 [tg P/ g soil which was observed in the 0-5 cm depth showed the

amended treatment containing over two times as much P as the unamended one (Table 4-

15).

The more resistant HC1 and residual P fractions which generally take longer to

change showed no significant trends of changes between amended and unamended

treatments. This observation was evident at all depths in the OG soil as was also the case

in the BD soil (Tables 4.13 & 4.15).

Unlike the BD soil, the difference between the sum P extracted from the amended

and unamended P fractions for OG was not significant (P = 0.05) for all P sources (Table

4-15). The dairy storage pond effluent and broiler litter compost litter treated soils

showed no difference between the amended and unamended soils. This means that the

WTR was not effective for these treatments in increasing the overall P retention capacity.

This may be due to the Ca or organic matter contents interfering with the ability of the Al

to complex or sorb the soil P. However, the WTR was effective at decreasing the

percentages of labile P in the soils to which they were applied (Appendix B). The

percentages of the more stable NaOH extractable Al and Fe bound soil P was also

increased in the soils amended with the WTR (Appendix B). The WTR amended soils

that had no P source additions had percentage increases in the soil NaOH Po fraction

while those with P source additions had percentage increases in NaOH Pi fraction. This is

was somewhat of an anomaly which I was unable to explain.













Table 4-15. Sequential data for amounts of P ([ag P/g soil) in the soil P fractions in the Oak Grove soil.
Control Dairy Fertilizer Broiler litter comnost
Labile P Am" NAm Am NAm Am Nam Am NAm
0-5 cm 64.2 At a 82.0B bt 62.2 A a 97.3 CD c 60.6 A a 92.4 B c 61.9 A a 76.7 BC b
5-15 cm 87.1 B 87.7 B 86.6 B 94.2 BC 84.2 B 101.4 CD 80.3 B 89.3 CD
15-25 cm 97.9 C 105.4 CD 98.5 CD 103.2 D 94.5 BC 109.1 D 93.8 D 93.8 D
NaOH P
0-5cm 63.0 Aa 69.0 Aa 193.0 Bc 123.0 A b 272.0 Cd 119.0 AB b 187.5 Bc 132.0 Ab
5-15 cm 81.5 AB 82.5 AB 143.0 A 133.0 A 136.5 B 122.5 AB 141.0 A 140.5 A
15-25 cm 93.5 B 101.5 B 140.0 A 140.0 A 142.0 B 134.5 B 145.0 A 139.5 A
NaOH Po
0-5cm 234.5 Bd 113.5 Ac 67.0 Ab 50.5 A ab 19.0 Aa 35.5 Aa 66.0 B b 44.5 ABab
5-15 cm 103.5 A 95.0 A 46.0 A 40.5 A 37.5 A 37.0 A 46.0 A 46.5 AB
15-25 cm 88.0 A 94.5 A 41.5 A 47.0 A 47.5 AB 44.5 A 41.0 A 45.5 AB
HCI P
0-5 cm 61.0 AB a 81.0 Ba 61.0 Aa 72.5 Aa 75.5 AB a 60.0 Aa 55.0 Aa 80.5 B a
5-15 cm 54.0 A 59.5 AB 71.0 A 71.5 A 92.0 B 69.5 AB 69.5 AB 58.5 A
15-25 cm 56.0 AB 58.5 AB 99.5 B 67.5 A 84.5 AB 61.5 A 61.5 AB 55.5 A
Residual P
0-5cm 40.5 ABbc 43.0 AB 33.5 A bc 33.5 A bc 29.5 AB ab 26.0 ABab 21.5Aa 31.5 Ab
5-15 cm 31.5A 40.5 AB 34.0 A 31.0A 30.0 AB 29.0 AB 32.5 A 43.0 B
15-25 cm 42.0 AB 42.0 AB 33.0 A 32.5 A 35.0 B 21.0 A 33.5 AB 37.5 B
Sum P
0-5 cm 462.5 B c 389.5 A b 417.0 A bc 376.5 A ab 456.5 C c 333.5 A a 392.5 A b 365.0 A ab
5-15 cm 357.0 A 365.0 A 380.5 A 370.0 A 380.0 AB 360.0 AB 370.0 A 377.0 A
15-25 cm 378.0 A 402.0 A 411.5 A 391.0 A 402.0 B 371.0 AB 375.0 A 372.5 A
Values with the same capital letters represent least squares means within each P source that are significant at the a = 0.05 level using pooled variance comparitive
estimates in an appropriate t-statistic.
Values with the same lower case superscripted letters represent least squares means among means in the 0-5 cm soil column depth that are significant at the a =
0.05 level using pooled variance comparitive estimates in an appropriate t-statistic.
Amended
T Unamended














CHAPTER 5
CONCLUSION

This study has provided information regarding the leaching and retention of P from

fertilizer and manure sources added to sandy soils. The notion that P applications to a soil

can be made based on the total P content of the P source irrespective of the source

characteristics is not a sound one. It was clear from the study that even in the short-term,

differences in P release characteristics among different P sources will occur. As in the

case of the dairy effluent used in the study, some manures may be very efficient sources

of readily available P, being equally or even more effective than commercial fertilizers.

If the applied source of P is in the form of a manure, the type of manure and the

physical state of the manure is critical to its P release characteristics in the soil. While the

diet and the physiological state of animals gives a general idea of the composition of

manures, the physical characteristics play a great role. Manures which are dried and

contain mixes of litter or bedding material such as wood shavings may not leach P from

soils as readily in the short-term as those applied in a liquid or semi liquid form.

To minimize immediate loss of P from applied manures to these soils, factors such

as soil fertilization history, time of application, crop cover and crop P removal

capabilities should be considered. Frossard et al. (1989) noted that soils with a history of

manure applications with more organic P relative to inorganic fertilizers are more prone

to leaching. Hence, even if there are management strategies in place to prevent loss of P

from the surface of these soils, the soil below the surface may contribute significantly to

the amount of P leached (McDowell and Sharpley, 2001).









Aluminum WTRs have a great potential to be used agriculturally to increase the P

sorption capacity of the A horizons of fields which are fertilized with manures. They are

relatively inexpensive, and the major operational costs associated with the use of them by

farmers may be in transporting them to the farms and operation of machinery during soil

incorporation. Their heavy metal contents are generally much lower than those of

biosolids, which are land applied even to fields of arable crops. However, it would be

ideal to incorporate the WTRs into the soils of new manure application fields. In the case

of soils where the entire soil column may be loaded with P from previous management

practices, the WTRs are still useful. In the event of flooding, or in places where the water

table fluctuates or is close to the soil surface, the WTR may be able to remove dissolved

P from the groundwater that resurfaces from greater depths in soils.

Effective P management can be done on farms where manures are land applied.

This requires future work on the potential use of Al WTRs and consideration of the above

mentioned factors affecting the leaching of P from the various P sources in collaboration

with extension agents and soil analytical laboratories.














APPENDIX A
PHOSPHORUS CONCENTRATIONS OF FERTILIZERS AND MANURES AND THE
QUANTITIES OF EACH APPLIED TO EACH SOIL COLUMN


Phosphorus source Phosphorus concentrations Quantity/ column



Dairy storage pond effluent 28 tg mL-1 636 mL

Triple superphosphate fertilizer 176,000 tg g-1 0.09 g

Broiler litter compost 28,000 ug g-1 0.65 g
















APPENDIX B
PERCENT CHANGES IN SOIL PHOSPHORUS FRACTIONS OBSERVED THE FOR
BYRD DAIRY AND OAK GROVE SOILS


Residual P


HCIP M 1.5%


NaOH Po


NaOH Pi


Labile P










Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


S17.0%








14.0%


Al-WTR amended




49.5%


18.0%


0 10 20 30 40 50


Byrd Dairy control treatment


21.0%


No Al-WTR


I 1.0%


17.0%


31.0%





30.0%


0 10 20 30 40 50










Byrd Dairy dairy storage pond effluent treatment


Al-WTR amended


21.0%


56.0%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


30 40 50 60 70


Byrd Dairy dairy storage pond effluent treatment

9.0%
No A1-WTR

1.5%


32.5%


24.0%


33.0%


0 10 20 30 40 50 60 70


- 5.5%

i1.5%


J 1 16.0%

0 10 20


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P











Byrd Dairy fertilizer treatment

5.0%


2.0%


Al-WTR amended


22.0%


49.0%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


Byrd Dairy fertilizer treatment

5.5%


2.0%


No Al-WTR


40.0%


17.0%


20 30


35.5%


40 50 60


22.0%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


0 10










Byrd Dairy broiler litter compost treatment


S6.0%


12.0%


Al-WTR amended


21.0%


51.0%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


50 60


Byrd Dairy broiler litter compost treatment

7.0%


3.0%


No Al-WTR


35.0%


22.0%


33.0%


10 20 30


0 20.0%


0 10 20


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


40 50 60







60


Oak Grove Dairy control treatment



t 13%


Al-WTR amended


50%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


Oak Grove Dairy control treatment

S11%


No A1-WTR
20%


29%


17%


10 15 20


23%

25 30 35


13%


15%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


0 5










Oak Grove Dairy dairy storage pond effluent treatment


168%


-15%


16%


Al-WTR amended


46%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


Oak Grove Dairy dairy storage pond effluent treatment

9%
No A1-WTR

19%


13%


32%


27%


0 5 10 15 20 25 30


S15%


0 10 20 30 40


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P











Oak Grove Dairy fertilizer treatment

6%


16.5%


4%


A1-WTR amended


59.5%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P












Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


Oak Grove Dairy fertilizer treatment

8%


No A1-WTR


18%


10.5%


35.5%


28%


S14%


0 10 20 30 40 50 60 70










Oak Grove Dairy broiler litter compost treatment


145%


14%


AI-WTR amended


17%


48%


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


Oak Grove Dairy broiler litter compost treatment

9%
No AI-WTR

22%


12%


36%


21%


10 20


S16%


0 10 20


Residual P


HC1P


NaOH Po


NaOH Pi


Labile P


30 40


















APPENDIX C
PHOSPHORUS CONCENTRATIONS FOR THE BYRD DAIRY AND OAK GROVE
LEACHATES


Total phosphorus in leachates from the Byrd Dairy soil


Al-WTR amended


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Control Dairy storage pond effluent
Triple superphosphate fertilizer Broiler litter compost


Total phosphorus in leachates from the Byrd Dairy soil


No Al-WTR


10
9
8
7
S6
' 5
4
X 3
U 2
1
0
-1


1 2 3 4 5 6 7 8 9 10 11
Leaching Event
Control
Triple superphosphate fertilizer


12 13 14 15 16 17 18 19


Dairy storage pond effluent
Broiler litter compost


15
14
13
12
11
S10
9
8
7
.1 6
5
4
1 3
U 2











Total phosphorus in leachates from the Oak Grove Diary soil


Al-WTR amended


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event


Control
Triple superphosphate fertilizer


Dairy storage pond effluent
Broiler litter compost


Total phosphorus in leachates from the Oak Grove Dairy soil


TNo Al-WTR


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event


Control
Triple superphosphate fertilizer


Dairy storage pond effluent
Broiler litter compost


14
13
12
11
S10
9

7
S6
S5
4
S3
2


S10
9
o 8
7
. 6
5
4
3
0







66



Soluble reactive phosphorus in leachates from the Byrd Dairy soil

11
10 Al-WTR amended

9
8
7
6
5
4 TJ
4
3
2



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event


Control

Triple superphosphate fertilizer


Dairy storage pond effluent

Roiler litter compost


Soluble reactive phosphorus in leachates from the Byrd Dairy soil


No Al-WTR


1 2 3 4 5 6 7


8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event


Control

Triple superphosphate fertilizer


Dairy storage pond effluent

Broiler litter compost


11
10
S9




. 6
5
S4
3
2
1
0






67


Soluble reactive phosphorus in leachates from the Oak Grove Dairy soil


Al-WTR amended


1 2 3 4 5 6


Control


7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event
Dairy storage pond effluent


Triple superphosphate fertilizer


Broiler litter compost


Soluble reactive phosphorus in leachates from the Oak Grove Dairy soil


No Al-WTR


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Leaching Event


Control


Dairy storage pond effluent


Triple superphosphate fertilizer


CN 9

S7
.2 6
I 5
4
3

2


:


Broiler litter compost
















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BIOGRAPHICAL SKETCH

Leighton Walker was born in Mandeville, Jamaica, on February 22nd, 1979. He is

the youngest of five children born to Herbert Walker and Valerie Walker. For his

undergraduate education, Leighton attended the University of the West Indies in Trinidad

and participated in a student exchange programme at Virginia Polytechnic and State

University, after which he received his Bachelor of Science degree in general agriculture.

After graduating in 2000, he returned to Jamaica for a few months. In August 2001,

Leighton started his master's degree in the Soil and Water Science Department at the

University of Florida.