Ertragspotentiale ökologischer Anbausysteme aus pflanzenbaulicher Sicht

The potential of Organic Agriculture to feed the world is currently under discussion. Contrasting statements concerning this issue are mainly due to missing distinction between socio-economic and biophysical impact factors, to methodical issues of yield comparisons and to sole regional observations. Instead of comparing individual data sets in meta-analyses it is proposed to explore yield potentials of different systems from an agronomic perspective. Yields in organic systems are predominantly restricted by N-availability as a function of legume growing. The potential of replacing mineral N by biological nitrogen fixation differs between regions, but generally limits the productivity of cereals. A major determinant for legume cultivation is low pressure on land use, i.e. where the availability of agricultural area per capita is high. Establishing organic systems with legumes in regions with intensive pure crop production, e.g. paddy rice in Bangladesh, would result in a significant decrease of cereal yield and production with a subsequent change in human diet