Pedologist

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The author attempted making the large soil thin section (soil thin section monolith) for the exhibition. The size is 30×14 centimeters. There were technically some probems to which I have to solve. One is size of monolith and the other is accuracy of monolith. These are restricted things caused from the ability of the tool and the machine (impregnation apparatus, fteezed drying machine, sawing machine and suface griding machine). The another is reinforcement of bonding strength of the soil sample and glass. This was solved by using the silane-conpling reagent. An unsettled problem is a dehydration of the soil sample. Soil thin section monolith of the each soil type studied was made as follow. Dry Podzolic Soils (PDI, under sud alpine conifers trees (Tsuga diversifolia, Abies Mariesii), Kokusidake, Alt. 2000, Nagano Pref.), Wet Iron Podzolic Soils (PW (i) I, under cool temperated broadleaved trees (BD (d), under cool temperated broadleaved trees (Fagus crenata), Mt. Naeba, Alt. 1350. Niigata Pref.), Brown Forest Soils (BD (d), under cool temperated broadleaved trees (Fagus crenata), Pass Yanagisawa, Alt. 900, Yamanasi Pref.), Brown Forest Soils (BD, under temperated conifers trees (Pinus densiflora), Tsukuba Botanical Garden, Alt. 25, Ibaraki Pref.), Red Soils (RD,under subtropical evergreen broadleabed trees, Ogasaware Titijima, Alt. 50, Tokyo Metro.), Peat Soils (Pt, High-moor, Kayanodaira, Alt. 1550, Nagano Pref.)

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The allophanic Andosols and non-allophanic Andosols are not srparated in the classification system of cultivated soils. But the difference is important from the viewpoint of chemical properties (espcially acidty), soil managemnt and land use. The exchange acidity Yl seem diagnostic in separating the two types. In an approach to separate these two types, we used the database of Soil Information System (JAPSIS), and about 4000 soil profiles of Andosols were separated between 'acid' type (Y1>5) and 'non-acid' types. Acid type of Andosls show a consistent difference in soil properties as well as in land use from 'non-acid' types, and are regarded as non-allophanic Andosols. Since the cultivated soils are heavily limed, the percentage of non-allophanic Andosols must be greater than that of 'acid' type. Regionality of the distribution of these two tyoes was also evident. 'Acid' type dominates in Tohoku, and Sanin regions where non-allophanic Andosols are known to occur widely, and non-acid type is widespread in Hokkaido, Kanto and Kyushu regions. Further information on Yl, particularly of subsurface soils will make us an real estimation possible on the distribution of non-allophanic Andosols.

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