抄録
1. Studies were carried on the three profiles of the terra-rossa-like soils occuring in "the great limestone bed" region (paleozoic) in western Chosen. In this district, the climate is rainy and hot in summer, whilst in winter dry and cold. The rain and N-S factors rather resemble those of brown forest soil zone than the Mediterranean factors. 2. The soils are composed of brownish red clay, tinged with purple, throughout the vertical section. However, the color of arable soil-horizon is somewhat faded, and the bottom horizon slightly light. 3. The top horizon (A_1) posesses a crumble structure of fairly good degree. The crumb or soil lump, however, gradually increases in size with depth, so that the structure gradually turns into coarse-granular (A_2) and then nutty (B) structures. Then the latter gradually merges into the bottom horizon (C_1) which is consistedof chemically well-weathered debris or detritus of shale. This is composed of brow nish red clay, being coated with black film of iron oxide. This horizon overlies the bed rock, limestone or dolomite. 4. The soils contain markedly large amounts of clay fraction and no gravel; sand and silt fraction being correspondingly small. The amount of sand seems to slightly increase with increasing depth of the soil horizon. 5. The pH of the soils ranges between 6.5 and 7. It gives no appreciable variation with varying depth of the horizon. The hydrolytic acidity is low and shows a decreasing tendency with increasing depth. 6. The total exchange-acidity, as determined by the ammonium acetate method, is 12〜17 m. e. This figure resembles that obtained by del Villar with Spanish soils. The capacity decreases with increasing depth. 7. The degree of base-saturation was found to be 80〜85% in one case, and 90〜95% in other two cases of the profile. Calcium occupies 40〜45% and magnesium 30〜40% of the total exchangeable, strong bases. The former percentage decreases while the latter increases with depth. 8. The chemical composition seems to resemble that of south French terra-rossa which has been given by Blanck as an analytical example in his book. The soils are generally more rich in magnesia than lime, and in potash than soda. The composition gives no marked variation with varying depth. 9. The molecular ratios SiO_2/Al_2O_3 and SiO_2/R_2O_3 of the colloidal clay fraction were found to be respectively 2.5〜2.8 and 2.0〜2.3.
