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Vertical Mobility and Dynamics of Phosphorus from Fertilizer and Manure in Sandy Florida Soils

Explore how phosphorus moves in sandy Florida soils when manure and fertilizer are applied, with focus on leaching characteristics, soil amendments, and impacts on soil retention capacities.

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Vertical Mobility and Dynamics of Phosphorus from Fertilizer and Manure in Sandy Florida Soils

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  1. Vertical Mobility and Dynamics of Phosphorus from Fertilizer and Manure in Sandy Florida Soils By: Leighton C. Walker

  2. INTRODUCTION • Animal manures contain vital nutrients (e.g. N & P) which can be used as crop fertilizers • Land application of animal manures is a convenient, cost effective means of utilization of animal wastes • Excessive nutrient application may increase risk of eutrophication of water bodies

  3. Some undesirable effects of eutrophication are: • toxic algal blooms • loss of natural aquatic vegetation • low dissolved oxygen concentrations • fish kills • unpleasant odors • loss of property value

  4. Population growth in the U.S.A has placed an • increased demand on agricultural land resources • more agricultural production on less land area • Nationwide total farmland decreased over 1.5 M acres (607,020 ha) (USDA, 2003) • Florida lost 100,000 acres (40,468 ha) (USDA, 2003) • Increasing numbers of livestock operations confine • large numbers of animals in small spaces • These are referred to as concentrated animal feeding • operations (CAFOs)

  5. The discharge P concentration limits from agricultural operations are constantly being reduced • Problems farmers now face are: • less land for livestock and poultry production • less cropland for application of increasing amounts of manure • more stringent P discharge regulations

  6. Animal manure types differ in • chemical and physical composition • nutrient availabilities • soil reactions • Soils also differ in nutrient histories, nutrient status • and P retention capacities • The soils of Florida are mostly sandy, coarse textured, • with generally low P sorbing capacities

  7. OBJECTIVES The objectives of this study were to evaluate: • The P leaching characteristics of two sandy soils with different fertilization histories using three P sources • The leaching characteristics of the different P sources (dairy storage pond effluent, poultry litter compost and triple superphosphate fertilizer)

  8. The effectiveness of an aluminum based water treatment residual (Al-WTR) as a soil amendment for increasing soil P retention • The overall effect of the treatments on the forms of P in the soils

  9. HYPOTHESIS • The heavily manure-impacted soil will release more P than the minimally-impacted soil • The triple superphosphate fertilizer will leach greater amounts of P than the animal manure sources • The Al-WTR will greatly increase the soil P retention capacity

  10. MATERIALS and METHODS • Column leaching study • Experimental Design - 2*2*4*4 • 2 soils (Byrd Dairy, Oak Grove Dairy) • 2 amendment treatments (Al-WTR, No Al-WTR) • 4 P source treatments - dairy storage pond effluent - poultry litter compost - inorganic fertilizer (TSP) - no P addition (control) • 4 Replications

  11. Soils were collected from the Ap horizons of hayfields of two dairies (Byrd and Oak Grove) • Byrd Dairy • mainly used in hay production operations • some inorganic fertilizer application

  12. Oak Grove Dairy • dairy effluent application for 10 -15 years • supplemental inorganic fertilizer application

  13. PVC columns • 7.5 cm I.D. • 30 cm long • packed with soil from Ap horizons (25 cm soil column) • 12% total porosity (68 mL) water added before leaching to reduce hydrophobicity • P sources and amendments were applied to the top 4 cm of soil

  14. Application rates • P sources - 40 kg P ha-1 (18 mg P/ column) • amendments – 5% weight of soil in top 4cm of column • Leached weekly for 19 leaching events - 250 mL rainwater (1 pore volume per event) - 5 ½ months

  15. Analyses • Soil Characterization - Mehlich-1 Al, Ca, Mg and Fe - Total carbon (TC) and total nitrogen (TN) CNS Analyzer (Carlo-Erba Instruments. Rodano, Milan, Italy) - Water soluble phosphorus

  16. Leachates • pH • Electrical conductivity (EC) • Soluble reactive phosphorus (SRP) • Total phosphorus (TP) • WTR characterization O’Connor and Elliot, 2000 • Fractionation was done on soil columns at 0-5, 5-15 and 15-25cm depth increments

  17. Fractionation: Modified Hedley fractionation procedure (1982) Soil 0.5 g HCl-P 1 M (16h) CaCl2-P 0.01M (16h) NaHCO3-P 0.5M (16h) NaOH-P 0.1 M (16h) Labile P Ca/Mg-P Inorg Fe/Al-P Residual-P ignition at 550oC followed by acid solubilization Org P = Total P – Pi

  18. RESULTS Table 1. Selected Chemical Properties from the Ap Horizons of the Byrd Dairy and Oak Grove soils (n = 6)

  19. Table 2. Selected properties of the Al-WTR used in the study (O’Connor and Elliot, 2000). Table 3. Phosphorus fractions, oxalate extractable P, Fe, and Al and P sorbing capacity of the Al-WTR (O’Connor and Elliot, 2000). § Phosphorus Saturation Index = oxalate P/oxalate Fe + Al (in moles)

  20. Trends in leachate pH changes for the amended and unamended Byrd Dairy soil Al-WTR 9.0 Control Dairy 8.0 TSP Poultry 7.0 pH 6.0 5.0 4.0 Leaching Event 3.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Control Dairy No Al-WTR TSP Poultry Control Dairy 9.0 TSP Poultry 8.0 7.0 6.0 pH 5.0 4.0 Leaching Event 3.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 No Al-WTR

  21. Trends in leachate pH changes for the amended and unamended Oak Grove Dairy soil 9.0 9.0 8.0 8.0 7.0 pH 6.0 6.0 5.0 5.0 Al-WTR 4.0 3.0 1 2 2 3 4 4 5 6 7 7 8 8 9 9 10 11 12 13 14 15 16 17 18 19 9.0 Leaching Event 9.0 9.0 8.0 Control Control Dairy Dairy TSP TSP Poultry Poultry 7.0 7.0 6.0 pH 5.0 4.0 No Al-WTR 3.0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 Leaching Event

  22. Trends in the electrical conductivity values measured in the leachates 6000 Byrd No Al-WTR Control 5000 4000 3000 Electrical Conductivity (μS cm-1) 2000 1000 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 9 9 10 10 11 11 12 12 13 13 14 15 15 16 16 17 17 18 19 19 Leaching Event 6000 Oak Grove No Al-WTR Control 5000 5000 4000 4000 3000 3000 Electrical Conductivity (μS cm-1) 2000 2000 1000 1000 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 Leaching Event Dairy TSP Poultry Dairy TSP Poultry

  23. Trends in soluble reactive phosphorus concentrations for Byrd and Oak Grove soils 10 Byrd Dairy 9 Control Dairy TSP Poultry 8 7 6 SRP concentration (μg ml-1) 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 0 Leaching Event 10 Oak Grove Dairy 9 8 7 6 SRP concentration (μg ml-1) 5 4 3 2 1 Control Dairy- TSP Poultry 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Leaching Event

  24. TP and SRP leached from Byrd Dairy and Oak Grove soils averaged overall treatments. 40 Byrd Oak Grove 35 30 30 25 25 20 20 Cummulative TP (μg P) 15 15 10 10 5 5 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 Leaching Event 40 40 35 35 Byrd Oak Grove 30 30 25 25 20 20 Cummulative SRP (μg P) 15 15 10 10 5 5 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 Leaching Event

  25. Cummulative mass of phosphorus leached from the Al-WTR amended and unamended Byrd Dairy soil after 19 leaching events Poultry 6.0 A Poultry 4.0 B Fertilizer 5.6 A Fertilizer 3.9 B Dairy 6.5 A Dairy 5.3 B Control 4.8 A Control 3.9 A 0.0 2.0 4.0 6.0 8.0 Mass P Leached (μg P) Cummulative mass of phosphorus leached from the Al-WTR amended and unamended Oak Grove Dairy soil after 19 leaching events Poultry 25.0 A Poultry 21.0 B Fertilizer 27.7 A Fertilizer 21.6 B Dairy 26.2 A Dairy 21.0 B Control 23.6 A Control 21.4 A 0.0 5.0 10.0 15.0 20.0 25.0 30.0 Mass P Leached (μg P)

  26. Fractionation: Modified Hedley fractionation procedure (1982) Soil 0.5 g HCl-P 1 M (16h) CaCl2-P 0.01M (16h) NaHCO3-P 0.5M (16h) NaOH-P 0.1 M (16h) Labile P Ca/Mg-P Inorg Fe/Al-P Residual-P ignition at 550oC followed by acid solubilization Org P = Total P – Pi

  27. Byrd Dairy 140 b b b 120 100 80 Concentration (μg P/ g soil) 60 a a 40 a a a a a a a a a a a a a a a a a a a 20 0 Control +Al WTR Poultry +Al WTR Fertilizer +Al WTR Dairy +Al WTR Fertilizer Poultry Control Dairy 300 b 250 Oak Grove Dairy NaOH P i b b 200 a a a a a a a a a a a a 150 Concentration (μg P/ g soil) a a a b b ab ab 100 a a 50 0 Dairy +Al WTR Control +Al WTR Fertilizer +Al WTR Poultry +Al WTR Control Poultry Fertilizer Dairy 0-5 cm 0-5 cm 5-15 cm 5-15 cm 15-25 cm 15-25 cm NaOH Pi Oak Grove Dairy NaOH Pi

  28. CONCLUSIONS

  29. Hypothesis 1 • The heavily manure-impacted soil will release more P than the minimally-impacted soil • Sandy soils with long animal manure application histories will most likely be at risk of leaching large amounts of P for long periods of time

  30. Hypothesis 2 • The triple superphosphate fertilizer will leach greater amounts of P than the animal manure sources • The application of liquid dairy effluent to sandy soils may pose a greater immediate risk of P loss through leaching

  31. Hypothesis 3 • The Al-WTR will greatly increase the soil P retention capacity • Aluminum based WTRs can increase the P retention capacity of sandy soils and also reduce the amounts of soil labile P

  32. ACKNOWLDEGEMENT Thank you to: Committee Dr. D.A Graetz (Chair) Dr V.D. Nair (Co-chair) Dr. W.G. Harris Dr. R.A. Nordstedt Others Dr. G.A. O’Connor Dr. K.M. Portier Dawn Lucas (Lab Manager) Colleagues and friends USDA – Initiative for Future Agriculture and Food Systems College of Agricultural and Life Sciences (UF)

  33. Questions?

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