Modelling of the nitrogen cycle in farm land areas

The authors propose a method of modelling the cycles of water and nitrogen in the soil in order to simulate the drainage flow of water and the flow of leached nitrate, the main inputs into a model of transfer in aquifers. The processes of the N cycle included here are: mineralization, nitrification, ammonium adsorption-desorption, immobilization of N from ammonium and nitrate, N uptake by plants and leaching of nitrate. The results of a limited test of the model using data from Dutch experimental farms showed that, on the whole, measured and simulated values were in reasonably good agreement, in spite of the relative simplicity of the model. However, the simulations do not give detailed information concerning the dynamics of nitrogen in the various layers in the soil.