日本の黒色森林土に関する研究 : 第1報緒論ならびに形態学的特徴とそれにもとずく暫定的分類

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The Black Forest Soils derived from andesitic volcanic ashes, are widely distributed on uplands, hills and mountains in Japan. They are characterized by a thick and black A horizon which is rich in humus. Though the former is not just the same as the latter, the Black Forest Soil closely resembles the Ando Soil, Black, which is recently named by some American pedologists, in many respects. Normal profiles of the soil in well-drained area consist of four or five horizons, and their, morphological characteristics observed are as follows : 1) A_0 layer (about 3〜5cm in thickness) Thin leaf litters with dark grayish brown organic substances partially decomposed. In grasslands, the layer is heavily matted with grass rootlets. 2) A_1 horizon (15〜40cm in thickness) Black or brownish black loam to silt loam, rich in humus. Very loose. soft and mellow in consistency, and floury feel between fingers. Fine granular structure weakly developed. Crumbs are very friable. 3) A_2 horizon (20〜50cm in thickness) It resembles the upper horizon in various respects, although the former is more compact and blackish than the latter. Loam to clay loam in texture and coarse or very coarse nuciform structure weakly to moderately developed. Lumps are very friable. The horizon gradually merges into the lower horizon and does not show any tendency of bleaching. In Onji type found in Eastern Kagoshima (in the vicinity of Kanoya City), a thin pumice layer occurs in the lower part of the A_2 horizon or in the upper part of the B_1 horizon. 4) B_1 horizon (15〜30cm in thickness) It is a transitional horizon. Dark brown loam to clay loam with some humus transported into the horizon from the upper part. Coarse or very coarse blocky structure moderately to strongly developed. Lumps are fine porous and friable. The boundary between the B_1 and the B_2 or B_2C horizons is somewhat wavy or tonguelike, though clearly defined. 5) B_2 or B_2C horizon The colours of the horizon, closely resembling those of the parent materials, range from very light yellowish brown to brown. It is obvious that colour by itself cannot be used as a criterion in soil classification, but when considered in connection with other morphological characteristics of the Black Forest Soils the difference in colour of the B_2 or the B_2C horizon is of extreme importance in the subdivision of the Black Forest Soils. Fine sandy loam to clay loam and moderately or strongly developed blocky structure. When dry, this horizon gives very coarse prismatic structure as usually seen in loessial regions. Lumps are very porous and friable. Compact and non plastic. In Onji type, the subsoil is saw-dust like in appearance. There are many minute fragments of glassy substances throughout profile. In Brown and Yellowish Brown types found in Kanto Plain, some small reddish brown lapilli occur in the B hofizon. From the results of the field observation carried out by the writer, it can hardly be doubted that the Black Forest Soils with developed profiles, as has already been stated by Thorp, are ABC soils, whereas their younger members belong to AC soils. In considering their morphological and chemical characteristics and origins, with considerable possibility we may say that the Black Forest Soils belong to one of the intrazonal soil types. Some of them have one or more buried profiles. Examples of these buried soils found in southern Kyushu are shown in Figures 1 and 2. According to the provisional classification based on their morphological characteristics and reactions, the Black Forest Soild as now recognized are classified into the following sub groups : 1) Onji type, 2) Brown type. 3) Light Yellowish Brown type, and 4) Yellowish Brown type. Main characteristics and distribution of these types are given in Table 5. Some Japanese pedologists have called them the Black Soils or the Prairie-like Brown Forest Soils. The Ando soils mean dark soils in Japanese language.
社団法人日本土壌肥料学会の論文
1950-03-31

日本の黒色森林土に関する研究 : 第1報緒論ならびに形態学的特徴とそれにもとずく暫定的分類

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日本の黒色森林土に関する研究 : 第1報 緒論ならびに形態学的特徴とそれにもとずく暫定的分類

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日本の黒色森林土に関する研究 : 第1報緒論ならびに形態学的特徴とそれにもとずく暫定的分類