Monday, November 13, 2006

The Role of Organic Phosphorus in Alum's Ability to Reduce Phosphorus Solubility in Poultry Litter and Litter Amended Soils.

Jason G. Warren, USDA-ARS Animal Waste Management Research Unit, 230 Bennett Lane, Bowling Green, KY 42104, Joshua McGrath, Univ of Maryland, 0214 HJ Patterson, College Park, MD 20742, and Chad J. Penn, Oklahoma State Univ, 367 Agricultural Hall, Stillwater, OK 74078.

Alum (Al2[SO4]3) addition to litter in poultry houses is an effective strategy for reducing phosphorus (P) solubility in the litter and litter-amended soils, thereby reducing the potential for soluble P losses in runoff. Although there has been much research on the subject, there is still uncertainty concerning how alum affects P speciation in treated litters. Moreover, less is known about the fate of these P species after incorporation into soils.  In addition, most research has focused on inorganic P forms; however, recent advances now permit more accurate determination of organic P species. Therefore, the purpose of this study was to evaluate the functional distribution of P species within alum-treated poultry litter and litter amended soils.  A laboratory incubation was conducted in which alum-treated and untreated poultry litter were incubated for 30 days at 30% moisture.  Following the poultry litter incubation, each litter source and KH2PO4 was incorporated into a Hartsells fine sandy loam (Fine-loamy, siliceous, subactive, thermic Typic Hapludults) and incubated for an additional 30 day period.  Phosphorus species were then determined in litter and the amended-soils using an operationally defined sequential chemical fractionation (deionized H2O, 0.5 M NaHCO3, 0.1 M NaOH, 1.0 M HCl, concentrated HCl, and H2SO4-H2O2). In addition, liquid-state P31 NMR was used to further characterize P forms extracted from soils and litters. This research is expected to demonstrate that alum addition to poultry litter affects organic as well as inorganic P species and that these changes in P speciation have a significant effect on P solubility in litter and litter-amended soils. This information will allow for better understanding of the long-term implications of alum use in poultry houses.