抄録
In the field experiment, winter crops (naked barley, wheat, rape and common vetch) were cultivated on soils where summer ones (upland rice, sweet poteto, peanut and millet) had been cropped. In the pot experiment, the soils from each of 3 nutrient element experimental plots where those summer crops had been cultivated were used, and naked barley and common vetch were planted in those pots. 1) Better growth of wheat was recognized by following peanut than after other crops, viz. the order being as follows : Peanut>millet>upland rice>sweet poteto and naked barley, rape and common vetch yields were in similar trends, respectively. The soils where peanut or sweet poteto had been cultivated contained more aggregate than the soils that other crops had been grown, after the harvest of succeeding winter crops, however, such a fact in soil structure was not recognized. Peanut and millet gave good influences on the succeeding crops. Wheat and naked barley were remarkably influenced by the preceding crops. 2) Better growth and dry matter yield of naked barley by the pot test were found when it followed peanut or millet than other crops, and it yielded the least when it followed sweet potato. It was the same with common vetch. Residual N in these soils was effective only a little on the succeeding crops, especially in the soils where sweet poteto or upland rice had been cultivated, but generally we recognized a more remarkable effects of residual P2O5 and K2O. Application of N was more effective than that of P2O5 or K2O, especially on naked barley following peanut and on common vetch following sweet poteto. This pot test showed the same results as the field test, and so, pot tests may be used instead of field tests in such cases as the present ones.
