SOILNDB: a decision support tool for assessing nitrogen leaching losses from arable land

To allocate resources effectively to reduce nitrate leaching and the resulting adverse effects on the environment, it is of great importance to quantify the contribution from different agricultural management practices and different agro–environmental conditions. In this paper we present a decision support tool, SOILNDB, that can be used to quantify nitrogen leaching losses from large areas of arable land where the availability of detailed data is limited. SOILNDB is also a useful tool for studying the effects of changes in agricultural management and land use on leaching, and for evaluating alternative management practices to minimise nitrogen leaching. The basis for SOILNDB is two widely used ‘research models’, SOIL and SOILN, which describe water and heat fluxes, and nitrogen transformation and transport processes in the soil. A parameter database and parameter estimation algorithms are used to convert the input data in SOILNDB to parameter values for the SOIL–SOILN models. Model outputs can be presented either in a summarised form with yearly averages, or in more detail as a time series with daily resolution. An illustrative example simulation shows how the model can be used to compare nitrate leaching under alternative management practices