Simulation of water and nitrogen balances of irrigated and fertilized corn-crop soil

Soil water and nitrogen dynamics under a corn-crop field in Northern Greece were simulated during the 1996 growing period and the subsequent noncropped period. The soil water and nitrogen simulations were evaluated using a one-dimensional model based on the Galerkin finite-element method. The simulations describe dynamic environmental conditions, irrigation schedule, and inorganic N applications. They were carried on two plots of the field that differed in the amount and timing of nitrogen fertilizer applications. Inadequate irrigation water was applied, resulting in low availability of water in the root zone. The qualitative and quantitative procedures for model evaluation showed that there was good agreement between the simulated and the measured values of water content and inorganic species of N at different soil depths and the cumulative N uptake by plants. The average error was 0.006 cm(3)/cm(3) for water content and ranged from -1.06 to 0.052 mug/g soil for NH4-N and from -0.107 to 2.753 mug/g soil for NO3-N. Different procedures for getting the characteristic curves result in differing water contents and nitrogen concentrations in the soil.