%A Knut Schmidtke %T How to optimise symbiotic nitrogen fixation in organic crop rotations %X By means of the analysis results and calculation methods presented in this contribution it could be shown that many possibilities exist in Organic Agriculture to optimise the symbiotic N2 fixation activity of cultivated legumes through agricultural management. Here stronger impacts on the level of the symbiotic N2 fixation activity through the choice of a site-related legume type and procedures to increase the yield of legumes have to be expected. By means of a decrease in plant available nitrogen in the soil during the cultivation of legumes the symbiotic N2 fixation activity of the legumes can be additionally increased. %D 2008 %L orgprints13272