Distribution of total and extractable forms of iron,manganese, and aluminum in development of rice soils of saga polder lands

The distribution of pedogenic oxides of Fe, Mn, and Al was described for rice soils of Saga polder lands and its relationship to soil development with time was investigated. The distribution of Mn largely parallelled that of Fe and in response to the soil development their accumulation occurred in the B horizons of the profiles. Manganese was the clement most susceptible to downward movement, which lad to a pronounced lowering of extractable Mn content in the surface horizons in well-developed soil morphology. By contrast, this is not the case for Al which, in general, had little change in extractable Al and a slight increase in total Al with depth as the time increased. Apparently the distribution of Mn was largely governed by the extent of reduction processes, whereas in the Al distribution clay migration may be a principal controlling factor. The distribution of Fe may be due chiefly to the reduction processes, with some contribution from the clay migration.