NUTRIENT EMISSIONS FROM AGRICULTURE IN THE NETHERLANDS, CAUSES AND REMEDIES

Agriculture causes 60% of the total nitrogen emissions and 40-50% of t he total P emissions to the surface waters in the Netherlands. These h igh emissions are mainly caused by the large amounts of fertilizers us ed 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 s trategy of gradual reduction of the nutrient applications to crops. Th e firsts two phases were aimedat stabilisation and a gradual reduction of the use of organic manure. The goal of the third phase is to accom plish 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 acce ptable emissions, mainly to surface waters. With the average excess ra infall 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 ga p between environmentally acceptable and present losses. Equilibrium f ertilization will not solve all problems at short notice. Therefore, a dditional techniques to reduce nutrient losses are in development. Exa mples are restoration of buffer strips and wetlands, lowering of groun dwater levels, dosing of ferric and aluminum compounds in the soils an d several additional measures in eutrophied lakes. Copyright (C) 1996 IAWQ.