Of the two areas, Suwa-lake and Tenryu-vally, in Nagano Pref., soil survey was made. Around the lake there were observed Half-bog soil, Meadow soils (including River-bed type) and Gray lowland soil; and, in the valley, Brown forest soil and Brown lowland soils (including River-bed type) (see Table 1-8 and Maps). From the results of physical and chemical analyses, the following inclinations were found (see Table 9-12). 1) Of Half-bog soil, subsoil was muck, of much C, and rich in humus. When incubated, the soil produced considerable amount of ammonium-N. 2) Compared to normal Meadow soil and Gray lowland soil, Meadow soil of river-bed type was very poor in its finer component; consequently, it had low water holding capacity. 3) Brown forest soil in surveyed area was of poor base status under the forest cover (refer to soils, 43,44,45,47 in Table 12); and it seemed to be increased in its saturation degree of CaO by the cultivation for farm (refer to soils, 20,21,22; and 33,34,35 in Table 12). 4) Brown lowland soil, somewhat artificially made by irrigation, had a tendency to accumulate its Ca content in G horizon. (refer to Soils, 30,31,& 32 in Table 12). In the case of Brown lowland soil of River-bed type, saturation degree of CaO seemed to be decreased in subsoil. 5) By irrigation, the soils of upland farm seemed to increase its finer parts and to decrease its saturation degree of CaO (refer to soils, 23 & 24 in Table 12). In order to increase the productivity of surveyed area, the following remarks could be paid for each soil type. 1) Of Suwa-lake area. According to the public plan, the whole area is fixed to be drained. When drained, Half-bog soil area, first of all, is expected to be suffered from an extraordinal increase of available N, originated from the decomposition of organic matter in the soil. This suffering is to be avoided by the application of N in properly reduced amount and also by the addition of phosphate. Among the Meadow soil area, the area occupied by that of River-bed type must care for its being easily leached. Some considerations such as soil covering with proper fertilization must be paid to overcome this leaching. Properly drained, Gray lowland soil area is expected to turn out as profitable farm of double crop a year and to be in response to heavy fertilization. 2) Of Tenryu-valley area. The irrigation is planned to be more widely applied in this area. The soils, so irrigated, have a tendency to be leached. Care must be paid for maintaining the nutrients in suitable amount by proper fertilization; especially for Brown lowland soil of River-bed type.
