抄録
Amount of crop in regions, where a transferring cultivation between paddy and upland fields is practiced, is always greater than that in regions, where rice plant is the only crop. To study the reasons for this increase, a soil survey of 16 regions, both types of cultivation where practiced was made. The redox potential of soils and the effects of drying were measured in the laboratory. Of the studies, we found the following results : (1) The experiment was carried on in four different types of soil; peat, muck, clay and sand. In the one crop fields, there was a reduction of the pan that was originally present in all four types of soil; in the transfer-cultivation fields granular structure developed in all four types of soils. (2) Samples of the non-air dry soils were flooded for three weeks at 25℃., and the redox potential were measured : in the one crop paddy fields the fall of the Eh was rapid, and except for the muck soil the degree of fall was low, but in the transfer-cultivation fields the fall was slow and the degree of fall was comparatively high, and the Eh differed with soil types in both fields. (3) The effect of drying was greater on the one crop paddy fields than on the transfer-cultivation paddy fields, but differed in its degree with the soil types.
