抄録
1) Study on the rotation has not yet been cleared scientifically, so that the rotation of farmers has been only depended upon their experience. To establish the theory of rotation, the 1st thing to do is to clear the characters of each crop and to find the rational combination of the former and succeeding crops. Viewing of this point, this experiment was planned and practised. 2) Each crop differs in the requirement of the amounts of manures and its constituents. Each crop also have different tolerance for the continuous cropping. These facts enable to manifest the character of each crop on the demand for manures. 3) The favourable hardness of soil for each crop may seem to exist, but the investigation should be practised more scientifically. 4) The root development and the root system of each crop were studied. The roots develops more widely and deeper as considered. Viewing of the character of roots, it seems to be important to investigate the rational soil treatment and the soil condition influenced by the roots of each crop. 5) The shape of crop vegetation influences remarkably on the cleanness of the fields. For instance, soybean eradicates the weeds and makes clean the fields. Each crop has different character of these points. 6) Viewing of these character, the rational rotation (specially, the former and the succeeding cropping) in this district may be that of the table 2. (This experiments are now going on.)
