Do organic farming practices reduce nitrate leaching?

If the different input intensities of N between organic and conventional systems were taken into account and corrected for, no differences in leaching losses between systems were found. However, a proper comparison of leaching between the two types of systems should take the yield into account. Attempting to do this in this review, we found only two studies which provided data for this. In both studies, specific conditions of the soil-a high organic matter content resulting in a high N mineralization at one site and a heavy clay texture resulting in very small leaching losses at the other site-did not enable us to come up with a clear-cut answer. Nevertheless, we could not find any evidence that nitrate leaching will be reduced by the introduction of organic farming practices, if the goal is to maintain the same crop yield levels as in conventional farming systems. Reduction of nitrate leaching is not a question of organic or conventional farming, but rather of introduction and use of appropriate counter- measures. This insight should guide our thinking when developing environmentally friendly and sustainable cropping systems.