Water solubility of phosphorus in animal manure compost

摘要

The characterization of phosphorus (P) in animal manure compost (AMC) is important to estimate both the risk of P loss from agricultural land and the availability for crops. In this study, 16 AMCs (4 cattle manure composts, 5 swine manure composts, 5layer manure composts and 2 broiler litter composts) were extracted by large amounts of water for many hours (sequential water extraction). The dissolution patterns of P and some cations were described using two kinetic models and the maximum amount of water soluble P (P_0) was determined statistically. The P_0 values were corresponded to the sum of WEP and NaHCO_3 extractable P by modified Hedley method, indicating NaHCO_3 extractable P fraction is soluble to water and available for crops. The P_0 values were positively (r=0.854,p<0.001) correlated with Mg_0, and negatively (r=0.492, p<0.05) correlated with water soluble Ca. The result suggests that the amount of labile P in AMC is controlled by Mg and/or Ca concentrations.