In each container, 25 cm. in diameter and 1 m. in depth, after packing sandy soil to a suitable depth according to that of the surface soil and a clay layer 20 cm. thick upon it, loam from an unfertilized field was laid as the surface soil in the depth of 10, 30 and 50 cm. respectively. Fertilizers were applied at the rate of 5 kwan per tan for each ingredient and in the following ways. A) All fertilizers were applied before filling the containers, mixing them with all surface soil. B) All fertilizers were applied in the surface layer shallowly in the usual way, before transplanting. C) Three tenths and two tenths of the amount of nitrogen were given on July 20th. and August 5th. respectively, and the rest was applied before transplanting, in the same way as in B. For each depth of surface soil and method of fertilizing two plats were set up, in one of which irrigated water was percolated from the bottom hole of the container once a week (P) while none was percolated in the other (N). Growing rice plants in these containers, the effects of these conditions were studied. The results are shown in Tables I, II, III, IV and V.
直徑 25cm., 深さ 1 m. の亞鉛引鐵板製の圓筒に, 底土として殆ど有機質を缺く砂質土, 其の上に20cm. の厚さの粘土層, 更に其の上に表土として無肥料の耕土を夫々 10, 30 及び50cm. の深さに填充した。施肥法としては, A) 肥料の全量を基肥として填充に先だち表土の全部に均一に混和するもの, B) 同じく全量を基肥とするも普通の方法にて表層に施用するもの, 並に C) B と同じ方法によるも窒素の一部を追肥とするものゝ三方法を區別し, 更に灌概水を一週一回透過するものと然らざるものとを區別して, 之に水稻を栽培し, 以て表土の深淺對此等の施肥法及び灌概水滲透の如何が水稻の成育に及ぼす影響に就て實驗した。