Recently KANNO (1956) and YAMAZAKI (1960) established independently excellent schemes of classification for paddy soils, based on hydromorphic horizon sequences which had been brought under both influences of ground water and of a lot of irrigation water attended with rice culture. Organic paddy soils, however, were excluded in their schemes. Besides it might be seen that their lower categories of classification were not appropriate to represent regular soil pattern from the genetical point of view. Therefore the authors tried to propose a tentative scheme of classification for paddy soils with special reference to the land development of alluvial plain, citing an example of soil survey around Shizuoka City. At first, they identified 2 genetic soil types such as Organic paddy soils and Inorganic paddy soils. The former were divided into 3 soil subtypes with reference to related natural soils, such as Bog soil-paddy soils, Muck soil-paddy soils and Black paddy soils which were derived from reworked "Kuroboku" or humic soil materials transported from adjacent upland soils. Inorganic paddy soils were divided into 3 soil subtypes dy hydromorphic features, such as Groundwater paddy soils, Intermediate paddy soils and Surface-water paddy soils. As for the third categorical unit, they tried to adopt "Bodensippe" proposed by EHWALD (1958) or "Rod" by Soviet soil scientists. This unit was already used by Pedological Institute of China (1959) in the classification of paddy soils. The third unit was identified by the degree of drainage and diagnostic features of parent materials, such as quantity and quality of organic matter as well as grain size distribution, all of which were regarded as dominant factors affecting profile characteristics of soils. The fourth unit was based on textures of surface soils similarly as the soil type in American system of soil classification. This scheme of classifcaion was applied to the cartography of paddy soils around Shizuoka City. It was proved a great success in illustrating the regular distribytion of soil pattern, closely related to land development of alluvial plain. For example, fingered pattern of coarse grained soils indicated that of past river-beds, while dark fine grained soils showed back marshes between them. Moreover, this soil map also served for technical grouping of soil capability.
