Simulation of phosphate leaching in catchments with phosphate-saturated soils in the Netherlands

The effects on phosphate leaching to surface waters of two scenarios for net phosphate input to sandy agricultural soils were estimated. WATBAL and ANIMO simulations for manure surplus areas in the Netherlands were used. The methodology and models were verified by comparing model results with measured values of the Schuitenbeek catchment. Simulated values of phosphate loads to surface waters and phosphate concentrations were underestimated by 10 and 30% respectively. Phosphate leaching to surface waters and phosphate concentrations hardly increase in the lower scenario with a net P2O5 input or `loss' of 10 kg per ha per year. With a P2O5 surplus of 40 kg per ha per year both leaching fluxes and concentrations increase