The differential equations that govern the water flow and the solute transport in an unsaturated soil, considering the water extraction by plants were solved using the finite difference method. A computer model named SIMASS-C (Simulation of the water and solute transport in the soil considering water extraction) was developed using Delphi language. The model allows to calculate the water content, matric potential, water flux and solute concentration through the soil profile. Besides that, the model output gives the growth and the density of the roots, the leaf area index and the crop evapotranspiration. To test the model, an experiment was conducted in a green house using 42 soil columns made of PVC tubes. In each column, corn was seeded and during 30 days after the emergence the soil water content was determined. The SIMASS-C was used to simulate the soil water content during the experiment. By comparing the simulated and the experimental data, it was possible to conclude that the SIMASS-C did quite well in predicting the soil water movement in the soil.
finite differences; iterative method; SIMASS-C
