Josan Manure-component Effects on P Release from Manure-amended Sandy Soils M. S. Josan

Introduction Active and abandoned dairies Continuous release of P from these soils even years after abandonment (Nair et al., 2003) Paucity of P retaining minerals Manure components are important in the fate of P in dairy manure-impacted soils Importance of Mg in P dynamics in these soils has not been recognized

Properties of Manure Impacted and Unimpacted Soils ImpactedUnimpacted pH EC (dS m -1 ) Total Ca (mg kg -1 ) Total Mg (mg kg -1 ) Total P (mg kg -1 ) Total Fe (mg kg -1 )190 – 1200 Total Al (mg kg -1 ) ImpactedUnimpacted pH EC (dS m -1 ) – 0.20 Total Ca (mg kg -1 ) – 640 Total Mg (mg kg -1 ) – 50 Total P (mg kg -1 ) – 190 Total Fe (mg kg -1 )190 – – 1800 Total Al (mg kg -1 )

Rationale High Ca concentrations and pH should favor the formation of relatively stable calcium phosphates Stable Ca-P minerals (such as apatite) have not been found in heavy manure- impacted soils (Wang et al. 1995) Non-formation of Ca-P minerals could be due to inhibition by Mg, biogenic Si, and DOC

Hypotheses The release of phosphorus (P) in dairy manure-impacted soils is controlled by sparingly soluble Ca and/or Mg- phosphate phases Magnesium phosphate is a manure component rather than a component formed in soil after manure application

Objectives Assess the release of Ca, Mg and P in soil solution from dairy manure- impacted soils Evaluate Ca and/or Mg-P association in dairy manure and manure-impacted soils

Materials and Methods Soil and manure sampling Particle size fractionation and chemical characterization of soil and manure samples Repeated water extractions Column leaching

Materials and Methods Chemical equilibrium modeling (V- MINTEQ) –Soil and dairy manure column effluents –Saturation paste extracts Chemical fractionation

Josan Fractionation Scheme Soil (2g)NH 4 Cl-P 20 mL 1M NH 4 Cl 2-h shaking Labile -P Total P Org. –P= (Total P- In -P) Nair et al., 1995 NaOH-P 20 mL 0.1M NaOH 17-h shaking Fe/Al -P HCl-P 20 mL 0.5M HCl 24-h shaking Ca/Mg -P Residual-P Ignition at 550 o C Acid solubilization Mainly organic -P

Josan Percentage of P Fractions in A-horizon of a Heavily Manure-impacted soil (TP= 2900 mg kg -1 ) 1 st NH 4 Cl Extraction Ca/Mg -P NH 4 Cl -P Residual -P Al/Fe -P Org. -P Hieltjes and Lijklema (1980) Nair et al. (1995)

Josan Percentage of P Fractions in A-horizon of a Heavily Manure-impacted soil (TP= 2900 mg kg -1 ) 2 nd NH 4 Cl Extraction Ca/Mg -P Residual -P NH 4 Cl -P Al/Fe -P Org. -P

Josan Percentage of P Fractions in A-horizon of a Heavily Manure-impacted soil (TP= 2900 mg kg -1 ) 3 rd NH 4 Cl Extraction Ca/Mg -P Residual -P NH 4 Cl -P Al/Fe -P Org. -P

Josan Percentage of P Fractions in A-horizon of a Heavily Manure-impacted soil (TP= 2900 mg kg -1 ) ‘n’ Extractions Ca/Mg -P Residual -P NH 4 Cl -P Al/Fe -P Org. -P

Josan Modified Fractionation Scheme Soil (2g) NH 4 Cl-P 20 mL 1M NH 4 Cl 2-h shaking 1 st Extraction NH 4 Cl-P 20 mL 1M NH 4 Cl 2-h shaking 10 th Extraction or Greater NH 4 Cl-P 20 mL 1M NH 4 Cl 2-h shaking 2 nd Extraction NH 4 Cl-P 20 mL 1M NH 4 Cl 2-h shaking 3 rd Extraction Residual-P Ignition at 550 o C Acid solubilization NaOH-P 20 mL 0.1M NaOH 17-h shaking HCl-P 20 mL 0.5M HCl 24-h shaking Ca, Mg, and P concentrations will be determined in each extraction

Materials and Methods Solid state assessments: –Density separation –X-ray diffraction (XRD) –Thermogravimetery (TG) –Scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDS)

Josan Solid State Assessment XRD TG SEM Air-dried soil Air-dried manureParticle size fractionation and pre-concentration ? P with Mg or Ca Density separation <2.0 g cm -3 >2.0 g cm -3 Density separation <2.0 g cm -3 >2.0 g cm -3 SiltClay

Statistical Analysis Analysis of variance (ANOVA) –The Student-Newman-Keuls Non-parametric statistics (the Kruskal- Wallis test)

Josan Preliminary Results

Josan SRP, Mg and Ca Relationships for Active Dairy Manure Soils during Repeated Water Extractions Josan et al (in press)

Josan SRP, Mg and Ca Relationships for Abandoned Dairy Manure Soils during Repeated Water Extractions Josan et al (in press)

Josan Speciation Data from Column Leachates Mineral Phase Formula ActiveAbandoned (SI = log IAP - log Ksp) Struvite (NH 4 MgPO 4 ·6H 2 O) Farringtonite Mg 3 (PO 4 ) Newberryite MgHPO 4 ·3H 2 O Monetite CaHPO Brushite CaHPO 4 ·2H 2 O Hydroxyapatite [Ca 5 (PO 4 ) 3 (OH)] Josan et al (in press)

Dot Map Images of Dairy Manure Clay Size Fraction

Expected Results and Implications P stabilization via crystallization of calcium phosphates (even at near-neutral pH) may be preempted by Mg-P association Mg-P association is a key factor for high P activities in these soils Approaches to minimize P release –P-retaining soil amendments –Management of animal diet to eliminate Mg-P formation.

Acknowledgments Supported in part by the USDA-NRI Committee Members –Dr. Vimala Nair (Chair) –Dr. Willie Harris –Dr. George O’Connor –Dr. Dean Rhue –Dr. Tom Obreza –Dr. Amelia Dempere (Materials Science & Engineering Department) Thanks are also due to several people in SWSD who have helped me since my joining the department

Comments and Suggestions Thanks