Measurement and estimation of the fertiliser value of pig slurry by physicochemical models: Usefulness and constraints

38 Pags., 4 Figs., 5 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/15375110Pig slurries (PS) are widely applied to soil as fertilisers. Compositional variability, as shown in this study, is the main constraint on their efficient use. Slurry samples, collected from 126 commercial pig farms were analysed and organic nitrogen (ON), ammoniacal nitrogen (AN), total nitrogen (TN), total potassium (TK), total phosphorus (TP) content, pH, EC (electrical conductivity), DM (dry matter) and OM (organic matter) quantified. Relationships between major nutrient contents of PS and its physical and chemical properties were analysed. AN and TK were linearly related to EC (p 40 dS m−1) linearity cannot be maintained, which has important consequences for direct slurry EC measurements. ON and TP in slurries were closely related (p < 0.0001) to DM with R2 of 0.90 and 0.68 respectively.This study was funded by the National Institute for Agricultural and Food Scientific Research and Technology of Spain (INIA), projects SC00-061, RTA04-114 and RTA10-126.Peer reviewe