A N-dynamics model for predicting N-behavior subject to environmentally friendly fertilization practices: II - Numerical model and model validation

Nitrogen dynamics in the soil under the condition of environmentally friend ly fertilization practices (EFFPs) is described by a comprehensive N-dynami cs model. The model (first paper of this series, Transport in Porous Media 31(3) (1998), 249-274) is different from other models in its capability of simulating the special phenomena related to the application of EFFPs. In th is paper, a finite difference method is used to solve the mathematical mode l. The numerical model is verified by simulating several water flow and con servative solute transport problems with existing numerical or analytic sol utions. The good agreements between our simulation results and the solution s given by others show that our model is reliable in simulating flow and tr ansport problems in the soil. Preliminary model validation is conducted by applying the model to simulate two field experiments. The acceptable agreem ents between our numerical simulation results and experimental data demonst rate that the model can reasonably model N-dynamics in the soil under field conditions.