Optimization of the Nutrient Management of Silage Maize Cropping Systems in The Netherlands: A Review

Abstract

Silage maize is, after grassland, the second largest crop in the Netherlands. The amounts of nutrients applied to silage maize have greatly decreased since the 1980s because of the implementation of a series of environmental policies. The aim of this review paper was to provide an overview of the nutrient management of and losses from silage maize cropping systems in the Netherlands during recent decades based on a literature review and a time series of nitrogen (N) and phosphorus (P) uses, yields, surpluses, and losses. The total N input as slurry to silage maize on sandy soils decreased from up to 500 kg N/ha in 1985 to approximately 180 kg N/ha in recent years. This decrease was due to the implementation of legislation with maximum permissible P application rates in the 1980s and 1990s, maximum permissible N and P losses in the 1997–2005 period, and of maximum permissible N and P application rates from 2006 onwards. Implementation of low ammonia (NH3) emission application techniques of manure in the early 1990s greatly reduced NH3 emission. The relative decrease of N losses from silage maize on sandy soils in the 1995–2018 period was 70% for nitrate (NO3) leaching, 97% for NH3 emissions, 65% for nitrogen oxide (NO) emissions, and 32% for nitrous oxide (N2O) emissions. The P surplus on the soil balance of silage maize decreased from approximately 150 kg P2O5/ha in the 1980s to less than 10 kg P2O5/ha in recent years, showing that P inputs and outputs are currently coming close to a zero balance in silage maize cropping systems. Although the emissions from silage maize cultivation have greatly decreased, further improvements in nutrient management are needed. The water quality standards have still not been met and there are new challenges related to the mitigation of emissions of ammonia and greenhouse gases.