Comparative Study of Two Nitrogen Models

The fate of nitrogen in the soil is of major concern because of the potential hazard for nitrogen, applied in excess of the natural decomposing capacity of the soil, to contaminate shallow and deep aquifers. For the prediction of the nitrogen behavior in soils simulation models are frequently used. In this study the transport and fate of nitrate within the soil profile was analyzed by comparing historic field data with the simulation results of two mathematical models, i.e., the water and agrochemicals in the soil crop and Vadose environment (WAVE) and DRAINMOD-N. After calibration and validation of both models, they were used to simulate the nitrogen transport and transformation of the Hooibeekhoeve experiment, situated in the sandy region of the Kempen, Belgium, for a 30-year (1969–1998) period. In the analysis a continuous cropping with maize was assumed. Comparison between experimental measured and simulated state variables indicate that the nitrate concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth, and distribution. Furthermore, the study reveals that the models used give a fair description of the nitrogen dynamics in the profile root zone at field scale. It was concluded that the calibrated models are useful tools to optimize the nitrogen application strategy resulting in an acceptable level of nitrate leaching for a long period as a function of the combination “climate–crop–soil–bottom boundary condition.”