Nitrogen and phosphorus losses from agriculture into surface waters; The effects of policies and measures in The Netherlands

The increased input of fertilizers and animal wastes after 1950 has boosted agricultural crop production to a high level in many industrialized countries, but it has also contributed to increased nitrogen and phosphorus emissions from agriculture to groundwaters and surface waters. This paper summarizes the pathways and controls of nitrogen and phosphorus losses to surface waters, and it presents estimates and predictions of the losses from agricultural soils in The Netherlands into surface waters, before and after the implementation of policies and measures to reduce nutrient losses from agriculture. Implementation of the nutrient accounting system MINAS, aiming at a step-wise lowering of nitrogen and phosphorus surpluses at farm level, will decrease the total nitrogen and phosphorus surpluses between the years 1985 and 2008 by 58 and 82%, respectively. These large decreases are the result of a strong decrease in the input via fertilizers and animal wastes, combined with only a minor decrease in the output via harvested products. Nitrogen emissions from agricultural land to surface waters will decrease by 38% between 1985 and 2008. Phosphorus emissions from agricultural land to surface waters are expected not to decrease on the short term. (C) 1998 IAWQ. Published by Elsevier Science Ltd.