茨城県火山灰土壤の分類学的位置に関する考察 : ソ連の赤色土の概念との対比において

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Refering to the concept of humid subtropical Red soils in USSR, the author attempted to consider the classification problems of volcanic ash soils in Ibaragi Prefecture. 1. The landscape of central to south west parts of Japan, including Kanto district, is that of "humid subtropic" region from the geographical concept in USSR. 2. The landscape of Kolkhida, west Caucasus, where Red soils develop, resembles to that of Kanto district. 3. The climate of Kanto district also resembles to that of the humid subtropical zone of middle China. 4. High clay content, well developed aggregates, low SiO_2/Al_2O_3 ratio of clay (<2), high accumulation of humus and its unique composition (humic acid/fulvic acid <0.6) and strong absorption power of phosphate are common characte ristics both of volcanic ash soils in Ibaragi and of Red soils in USSR. 5. Mineral compositions in clay fractions of volcanic ash soils in Ibaragi prisist of allophane, gibbsite and at times of halloysite. This is one of main different point against Red soils, clay minerals of which consist dominantly of halloysite. However, the author considered, from the experimental results of vertical distribution of clay minerals, that the dominant process of soil formation is a type cf allitizaticn, that is, accumulation of allophane A in the lower horizons with romairing gibbsite in the upper horiizons. 6. From the reasons above mentioned, the author regards volcanic ash soils in Ibaragi prefecture as a special genetic soil type of humid subtropic, analogous to Red soils, but not to Brown Forest soils.
日本ペドロジー学会の論文
1960-08-01

茨城県火山灰土壤の分類学的位置に関する考察 : ソ連の赤色土の概念との対比において

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