北九州福岡市外香椎の赤色土

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It is expected from the climatic condition that Red and Yellow Soils may be found in most places of the south-western part of Japan Where volcanic ashes have not deposited. In this paper the morphological and chemical characteristics of the Red Soil occurring in Northern Kyushu Which belongs to the warm and humid temperate region, are described. The profile characteristics of the Red Soil formed over the highly unsaturated alumino-silicic shale of the Tertiary Period are shown in Table 1. In considering the fact that the A horizon does not show any evidence of bleaching, it is clear that the Red Soil is not identical With the podzolic Red Earth (by THORP). Although SWANSON has designated the Red Soil as the Reddish-Brown Lateritic Soil which is characterized by friability in consistency, the crumbs of the Red Soil in Kyushu, however, do not possess such friability when dry and, consequently, the soil cannot be regarded as the Reddish-Brown Lateritic Soil. In our opinion the soil rather resembles the Red Earth (non-podzolic) of Central and South China (by THORP) in many respects. The mechanical and chemical characteristics of the soil are given in Table 2. The table shows heavy clayey textures throughout the profile and, especially, an accumulation of clay in the B horizon. It is probable that some of the clay in the B horizon has been mechanically washed down from the present A horizon and, perhaps, from the past upper horizons which had been removed by erosion. The soil is characterized by the low content in organic matter, the strong acidity, the high degree of leaching of alkalies and alkaline earths, and very low base status. In particular, it is interesting to note that the acidity, as measured by pH value, increases with the depth. Such a increase in acidity in the red soils of the tropics has been noticed by DOYNE and other English soil scientists, and furthermore, TAMACHI has also recognized such feature in the podzolic soils derived from shales of the Tertiary Period in Northern Japan. Such feature of the Red Soil in Kyushu may be explained by the fact that the parent materials possess the extremely low base status. Besides, it must be remarkable that the exchangeable acidities (y_1), as have already been noticed by KAWAMURA and AOMINE, are stronger than the hydrolytic ones (y_1) in the lower horizons and the parent materials. The chemical compositions of the colloidal fraction show a slight accumulation of iron in the B_1 horizon. Silica-alumina ratios of the colloids are about 2.5 which would place them in the group of siallitic red earths according to HARRASSOWITZ's classification, and these ratios resemble those of the Red Earths in China. Since the exchange reactions (pH in water minus pH in 0.01n sodium sulphate solution) of air-dried soil materials give approximately an exchangeable neutrality throughout the profile, it may be considered that the Red Soil in Kyushu, as MATTSON has stated, is not cationically eluviated, but it belongs to the anionically eluviated group occupying an intermediate position between brown forest soils and lateritic (allitic) soils. The Red Soil of this type has its narrow distribution in Japan.
社団法人日本土壌肥料学会の論文
1950-12-30

北九州福岡市外香椎の赤色土

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