Abstract

The technical background to supporting the policy decisions on allocating phosphate-saturated soils and tackling the problems which these soils cause are presented here. Since 1987 the Dutch government has taken several steps to diminishing the problem of phosphate-saturated soils.New legislation will become available in 1998 for regulating the use of nutrients. The Ministries of Agriculture, Nature Management and Fisheries (LNV) and of Housing, Spatial Planning and the Environment (VROM) are planning to issue a general administrative order (GAO) to regulate phosphate use on phosphate-saturated soils. Several choices have to be made beforehand (1) Should the GAO cover the total agricultural area or should it be limited to, for example, the areas with known high historical loads? (2) What method should be used to identify phosphate-saturated soils? (3) Should management of all phosphate-saturated soils be restricted by the GAO or only the most polluted ones? (4) What level of net phosphorus export from the fields for which the GAO prescribes management restrictions should be implemented? Alternative answers to each of these questions have been formulated, with the pro's and cons for each given. Answers from the perspective of the GAO regulating farm management pertain to the national scale. The alternatives described can also be used for regulation limited to selected areas, such as those for nature conservation. In this case, methods described here can be used to select fields within the selected areas. In conclusion, several suggestions for future research are given, such as focusing on the effects in the long and medium term of soil phosphorus depletion on both agriculture and the environment. Although there are still questions to be answered, it has been made clear that the phosphorus status of most soils in the Netherlands at the moment is unnecessarily high from both the agricultural (plant production) and the environmental viewpoints.