抄録
In the rice/znon-rice cropping systems on heavy paddy soil, adequate drainage, pulverizability, and traf-ficability during the non-rice phase are necessary. Effects of tillage method on physical properties of heavy paddy soil were investigated. In anticipation of conversion of puddled ricefield to non-rice cropping, it is desirable that land preparation for the final rice crop should not destroy all soil structure. One non-puddling land preparation method is to rotovate only those strips of soil along which rice shall be transplanted. The grain yield of rice using this method was equal to that from conventional puddling. After rice harvest, permiability of strip-tilled soil was higher than that of puddled soil and rotovation was relatively easy. Seedling-emergence rate for a succeeding wheat crop and the yield thereof was higher than from soil previously puddled. In studies of wheat-soybean systems on heavy clay soil, emergence, rooting and yield of soybean were higher with non-tillage than with conventional tillage. In rice-wheat-soybean sequences on heavy clay, soil, the suitable tillage methods gave high production.
