Abstract
Observation of soil profiles in reference to the distributions of active and inactive oxides throughout the soil profiles of unmatured dry rice fields was made. Though many years elapsed since the cultivation of rice began in each field, the accumulation of the active iron oxides just below the furrow slice was scarcely found by the macroscopic observation. Somewhat ill drainage of the field was considered to be the principal cause of this phenomenon. The results of analyses are illustrated in Fig. 1,2,3,4,& 5,and the followings are concluded ; 1. Active oxides had been leached out, when the soils began to be used as the paddy field. 2. But in Soil A, active manganese oxides have been accumulated in the horizon below the furrow slice after using as the paddy field, and in Soil B, active manganese oxides and iron oxides have been accumulated. 3. Decreases of active alumina in the furrow slices are due to the downward movements of clay in addition to the lateral movements, though the drainages are not good.
