EFFECTS OF DIFFERENT SPECIES AS GREEN MANURE ON YIELD AND PROCEEDS OF THE SUBSEQUENT CROPS

In three years of field trials and under three different climatic conditions (''dry'', ''wet'', ''rough''), the effects of different legumes as under- and stubble-seed and of non-legumes only as stubble seed, were tested on the yield and proceeds of the subsequent crop. The highest yield surplus compared with the respective untreated plot was reached with underseeds. In the rather dry area alfalfa (+20 % yield of the subsequent crop) was most effective, under humid conditions (+30 %) and under rough climatic conditions (+40 %) white or red clover. Stubble seeds had much lower positive effects. In the case of cruciferae the yield surplus of the subsequent crop ranged between 3 and 12 %. The economic proceeds (after deduction of the expenses for seed, soil cultivation etc.) were only very slightly positive with alfalfa (dry climate), but highly positive with red and white clover (humid and rough climate). The nitrogen effect in these trials was about 90 kg N/ha with alfalfa under dry climatic conditions and about 60 kg N/ha with red or white clover under wet or rough climatic conditions. The influence of legumes on the yield of the covercrop was generally low, only on one site yield losses of the covercrop were observed, when Persian clover was grown as underseed. Under more humid or rough climatic conditions red or white clover can be recommended as underseed. With these green manures financial advantages can be expected. Under rather dry climatic conditions alfalfa as underseed has positive yield effects in the subsequent crop, but in the short term no financial advantages.