Abstract
We developed a numerical model to simulate water and nitrogen transport and transformations through water-unsaturated, multilayered soil profiles. The nitrogen transformation processes considered were nitrification, denitrification, immobilization, mineralization, and ionic exchange of ammonium. Plant uptakes of water and nitrogen were also included. We used an explicit-implicit finite difference approximation method to solve the nitrogen transport and transformation equations simultaneously with the water flow equation. Model evaluation and sensitivity analysis for a wide range of values for the rate of nitrification, distribution coefficient for ammonium exchange, and rate of N uptake were investigated. We developed a numerical model to simulate water and nitrogen transport and transformations through water-unsaturated, multilayered soil profiles. The nitrogen transformation processes considered were nitrification, denitrification, immobilization, mineralization, and ionic exchange of ammonium. Plant uptakes of water and nitrogen were also included. We used an explicit-implicit finite difference approximation method to solve the nitrogen transport and transformation equations simultaneously with the water flow equation. Model evaluation and sensitivity analysis for a wide range of values for the rate of nitrification, distribution coefficient for ammonium exchange, and rate of N uptake were investigated. © Williams & Wilkins 1981. All Rights Reserved.