Agricultural nutrient losses to surface water in the Netherlands: impact, strategies, and perspectives

Nutrient emissions from agricultural activities have become the dominant source of nutrient loads to freshwater in the Netherlands. This paper focuses on nutrient emissions from agriculture, emphasizing nutrient loads to surface waters, and strategies and perspectives to reduce these emissions. Although adverse environmental effects of intensive agriculture have been known for several years, it was not until 1987 that stabilization of animal manure production and application began. Since 1991 manure application rates have been reduced. Recently, application standards have been replaced by agriculturally inevitable nutrient losses and environmentally acceptable nutrient losses and these losses are reduced to an equilibrium fertilization in 2010, defined as the supply of manure and fertilizers that meets crop uptake and compensates for inevitable losses. In the 1980s, the most important tool to manage nutrient losses was a manure bookkeeping; recently a mineral bookkeeping has been introduced. Agricultural nutrient emissions to and their impact upon surface waters have been estimated from field experiments and model calculations, which indicate that the proposed legislation will not significantly improve water quality. Increasing areas will be saturated with P, especially where intensive livestock farming is located on sandy soils. Tailor-made regional programs are necessary to achieve ecological restoration of surface waters, with priority for catchment areas with vulnerable receiving waters. These programs may consist of a further reduction of nutrient application rates, hydrological measures, selection of crops that extract P from the soils or measures to increase the P adsorption capacity of the soil, and buffer strips