title: Phosphorus sorption and availability in soils amended with animal manures and sewage sludge.
abstract: Soils that receive large applications of animal wastes and sewage sludge are vulnerable to releasing environmentally significant concentrations of dissolved P available to subsurface flow owing to the gradual saturation of the soil's P sorption capacity. This study evaluated P sorption (calculated from Langmuir isotherms) and availability of P (as CaCl2-P and resin P) in soils incubated for 20 d with poultry litter, poultry manure, cattle slurry, municipal sewage sludge, or KH2PO4, added on a P-equivalent basis (100 mg P kg(-1)). All the P sources had a marked negative effect on P sorption and a positive effect on P availability in all soils. In the cattle slurry- and KH2PO4-treated soils, the decreases in P sorption maximum (19-66%) and binding energy (25-89%) were consistently larger than the corresponding decreases (7-41% and 11-30%) in poultry litter-, poultry manure-, and sewage sludge-treated soils. The effects of cattle slurry and KH2PO4 on P availability were, in most cases, larger than those of the other P sources. In the poultry litter, poultry manure, and sewage sludge treatments, the increase in soil solution P was inversely related (R2 = 0.75) to the input of Ca from these relatively high Ca (13.5-42 g kg(-1)) sources. Correlation analyses implied that the magnitude of the changes in P sorption and availability was not related to the water-extractable P content of the P sources. Future research on the sustainable application of organic wastes to agricultural soils needs to consider the non-P- as well as P-containing components of the waste.
authors.affiliation: Department of Soil Science, The Univ. of Reading, Whiteknights, P.O. Box 233, Reading RG6 6DW, UK.
authors.forename: Muhammad Tariq
authors.initials: MT
authors.lastname: Siddique
authors.forename: J Stephen
authors.initials: JS
authors.lastname: Robinson
mesh_terms: D000327:Adsorption; D000383:Agriculture; D000818:Animals; D001682:Biological Availability; D002122:Calcium Chloride / Q000737:chemistry; D008372:Manure; D008962:Models, Theoretical; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry*; D011200:Poultry; D018570:Risk Assessment; D012722:Sewage / Q000737:chemistry*; D013696:Temperature
chemical_list: D008372:Manure; D012722:Sewage; D010758:Phosphorus; D002122:Calcium Chloride