On the dry land conditions, the factor which, in relation to the soil texture, affects plant growth the most is the moisture condition. When irrigated abundantly, as in the case of rice culture, however, the moisture being sufficient, the nutrient-supplying condition of the soil and the root activities play a more important role, which differ according to the soil texture. Each of the factors involved in the rice yield―the number of tillers, the ratio of the number of heading tillers to the total, the number of spikelets per ear, the ratio of fertility and the weight of grains of an unit number,―appears to be affected by the nutritive condition of the plant at the period when the respective process is taking place, and with the same factors of aeration, the nutritive condition of the plant would in turn be determined by the nutrient-supplying power of the soil and the root activities. From such a view point, and in order to study the effects of the soil texture, the method of manuring and the percolation of irrigated water on the plant growth, the experiments presented here were performed.