Comparisons of Nitrogen Leaching in Ecological and Conventional Cropping Systems

Abstract

ABSTRACT A cropping system project aimed at developing cropping systems which minimise nutrient leaching and maximise food quality and economy, was started at Apelsvoll Research Station in 1990. The experiment involves cash crop and forage crop systems with conventional and ecological farming. The systems are different with regard to crop rotation, nitrogen fertilization, soil tillage and plant protection. They are going to be improved by step-by-step changes. In the first experimental period, 1990/93, more than 80% of the nitrogen runoff was lost as nitrate in the drainage water. Averaged over all years and cropping systems the nitrate losses were 21.2 kg/ha. The nitrate runoff in the conventional cash crop system was more than twice as high as in the ecological cash crop system. For the forage crop systems the nitrate loss in the ecological system was reduced by 36% as compared to the conventional system. There was high variation in nitrate losses between the years. The most important factors influencing the nitrogen runoff in the different cropping systems seem to be crop rotation, soil tillage, time of manure application and amount of fertilizer.