Impact of manure on accumulation and leaching of phosphate in areas of intensive livestock farming

Phosphate leaching from agricultural soils may affect the surface water quality in areas with shallow water-tables. In the Netherlands, areas with high livestock concentrations show high percentages of phosphate-saturated soils and high degrees of phosphate saturation. In the most strongly affected areas, phosphorus concentrations in streams have reached values of 1 mg/l owing to leaching from phosphate-saturated soils. In less affected areas, phosphate loads to surface waters may also increase at moderate soil phosphate levels and inputs, owing to the overdose of phosphate required to improve and control soil fertility. Part of this overdose leaches to the subsoil and, in the long term, to surface waters.