Mathematical simulation of nitrogen interactions in soils

Four mathematical models were evaluated for their ability to describe the fate of nitrogen (N) in the soil environment. The first model is a general one which accounts for convective-dispersive N transport under transient water flow conditions with active N uptake by plants. Model II considers N transport to be only of the convective type, whereas model III considers N uptake as a passive process. In contrast, model IV considers N transport under conditions of steady water flow in the soil. Experimental data from lysimeter studies for two soils showed that the convective model (II) and the steady state model (IV) are inferior in describing N transport in comparison to models I and III. It is concluded that transient water flow in the soil system as well as the convective dispersive transport mechanisms must be considered for reliable simulation of N behavior in the soil environment.