Nutrient emissions from agriculture in the Netherlands, causes and remedies

Abstract

Agriculture causes 60% of the total nitrogen emissions and 40-50% of the total P emissions to the surface waters in the Netherlands. These high emissions are mainly caused by the large amounts of fertilizers used on Dutch farms. On average, 39 kg P ha−1 and 340 kg N ha−1 are given in excess to the uptake by the crop. The Netherlands follows a strategy of gradual reduction of the nutrient applications to crops. The first two phases were aimedat stabilisation and a gradual reduction of the use of organic manure. The goal of the third phase is to accomplish equilibrium fertilization in the year 2000. This means that the amount of fertilizer given may not exceed the crop uptake, considering an acceptable loss to the environment. The losses are based upon acceptable emissions, mainly to surface waters. With the average excess rainfall in the Netherlands, the water quality standards are met with a loss of 0.4 kg P ha−1 and 6 kg N ha−1, much lower than the present excesses of minerals. The challenge for the future is to close the gap between environmentally acceptable and present losses. Equilibrium fertilization will not solve all problems at short notice. Therefore, additional techniques to reduce nutrient losses are in development. Examples are restoration of buffer strips and wetlands, lowering of groundwater levels, dosing of ferric and aluminum compounds in the soils and several additional measures in eutrophied lakes.