Simulating crop production and nitrate leaching losses from organic arable crop production

Summary

Crop models can be powerful tools to analyse the effect of changes in management of cropping systems on productivity and environmental impact, provided the models have been thoroughly tested. The FASSET model was found to adequately reproduce effects of management (manure and catch crops) and of site (soil and climate) on crop yields and nitrate leaching from a 4- crop rotation with a grass-clover green manure crop in one out of four years. Scenario analyses shown that the nitrate leaching increased relatively more with increasing N fixation in the grass-clover than did the crop yields. The yields could be increased and the nitrate leaching reduced by using catch crops and/or using the grass-clover for biogas instead of a green manure, assuming that the digested slurry was returned to the cereal crops.