SOIL and SOIL-NO at catchment scale--a case study for an agriculture-dominated catchment.

A one-dimensional model, SOIL/SOIL-NO, is used to simulate the water and nitrogen balance at catchment scale. The objective is to use the model in simulating the effects of best management practices on nitrogen runoff. The model was applied to individual farm fields in an agriculture dominated catchment and simulations were carried out for the period from 94-98. The results were promising. The simulated nitrogen runoff agreed quite well with the measured nitrogen loss at the main station. The effects of best management practices like optimal fertiliser application, catch crops and irrigation were simulated. For this particular catchment, the introduction of catch crops resulted in the best effect on reducing nitrogen runoff from agricultural dominated catchments.