The occurrence of vesicular-arbuscular mycorrhiza in agro-ecosystems

Abstract

In a long-lasting field experiment at the Research Station Hanninghof at Dulmen (Westphalia), laid out in 1971, the inoculum potential (IP) of vesicular-arbuscular mycorrhizal (VAM) fungi of soil from winter barley in a continuous monoculture (CM) and in a four-years cereal crop rotation (CR: winter wheat, winter barley, winter rye, oats) was estimated from 1980–1982. The influence of green manure and increased mineral N-fertilization (100 and 200 kg ha−1) on VAM-IP was also assessed. VAM-IP was high at both levels of N-application, although the higher N-fertilization resulted in a reduction of VAM-IP in winter barley — in CR as well as in CM. No influence of N-fertilization on VAM-IP was observed with oats and winter rye, which were only cultivated in CR. Green manure had a negative effect on IP in CM barley, but not in CR barley. This may be due to the annual applications of green manure in CM, while green manure in CR was only applied prior to the cultivation of oats and winter wheat, but not to winter barley. Except for the effects of green manure remarkable differences in VAM-IP were found neither in CR nor in CM of winter barley. This is also reflected in the yields of barley in CM and indicates the relative self-tolerance of winter barley.