カバークロップの種類と刈取りの有無がロータリ耕うん性能に及ぼす影響

Abstract

Cover crops may be effective tools for managing the sustainable agriculture, however, tillage systems should be discussed how to introduce cover crops to the farmer's field. In this research, we investigated the performance of rotary tillage in the cover crop fields compared with fallow. Main results are follows.1) Before rotary tillage, the soil dry densities in the 15-20cm soil depth layer in the cover crop fields were lower than that in the fallow field. After rotary tillage, soil dry densities in the fields of sub clover, crimson clover, and heary betch were almost same as that in the fallow, but that in the rye field was the lowest.2) After rotary tillage with 3 levels of tilling pitch ranging from 1.0 to 7.0cm, the mean diameters of soil clods in the fields of cover crops were larger than that in the fallow field. One of the reasons was that there were some soil clods with diameter over 32mm in cover crop fields.3) The problem that the cover crops were wound around the shaft of rotary tiller during tilling was obviously decreased by mowing the cover crop before rotary tillage.4) After rotary tillage with 1.0cm tilling pitch, 60-70% of the plant bodies of cover crops was buried under the 5cm depth layer of soil in the fields of sub-clover, crimson-clover and heary betch, but that in the rye field was buried only 50%.5) After rotary tillage with 1.0cm tilling pitch, the emergence ratios of silage corn as a subsequent crop in the fields of sub-clover, crimson-clover and heary betch were over 75%, these values were almost same as that in the fallow field. However, that in the rye field was the lowest.6) Rotary tillage with 1.0cm tilling pitch after mowing made an appropriate seedbed in the fields of legume cover crops, because legume cover crops did not have so much dry matter and stem strength. Meanwhile, rotary tillage in rye field did not make a good seedbed with any tilling pitch and regardless of mowing treatment. These results suggested that another tillage system should be appropriate in the field of rye cover crop.