Abstract
1. This experiment was carried out with an aim to get the information concerning the favourable growth-type of potato plants. 2. Irish potatoes were grown on the virgin volcanic ash soil, and 6 plots, to which equal amount of fertilizers were applied, were arranged with the depth and the rate of fertilizers variously combined as follows. [table] A, B, and C denote the depth of fertilizers applied in band, namely, 10, 20, and 30 cm from the surface of soil respectively. Side-number shows the ratio of fertilizers applied. *Fertilizers were applied alike in the respective depth. **Amount of fertilizers applied which has been customarily used in the cultivated soil. 3. The ecological and physiological responses of the potato plants to the treatment described above were clearly distinguished, and 4 growth-types were classified according to the seasonal changes of the quantity of growth, the dry matter produced, and the nuttrients absorbed. 4. Tuber yields were the highest at A7B3 plot, and in order of A3B7, A10, A7C3, ABC, A3C7, (Ak) they decreased gradually. This means that the tuber yields are closely realted with the root-development. It may be also stated that the potato plants absorb almost all of the nutrients from soil up to 20 cm in depth, but not so much from soil over it. From these results stated above, it will be concluded that fertilizers should be applied with consideration of the favourable growth-type of potato plants.
