Abstract
This paper deals with the morphological, mechanical and chemical characteristics of the red soil formed over the terrace land of Koradai, near Kurume. The results obtained are as follows : 1. Main soil formers and profile characteristics of the soil are shown in Table 1. The soil consists of a thin, slightly dark-colored surface soil and a light brown subsurface soil followed by a compact red dish brown subsoil underlain by yellow sand. The lower part of the A horizon does not show any evidence of bleaching or fading, and the soil has a very slightly developed profile. 2. Mechanical and chemical characteristics of the soil are given in Table 2. According to heavily leaching process, the soil is very strongly acid in reaction and the degrees of base saturation are very low, i.e., about 7 per cent. The colloidal clays of the soil are more siallitic in composition than those of the red-yellow soils with same origin, found on the Pacific Coast of Central Japan. Their molecular ratios closely resemble those of the red soils derived from limestone and shale in Japan, and of the red soils of South China. 3. Exchange reactions (pH in water minus pH in 0.01 n Na_2SO_4) of the various horizons show neutrality or alkalinity. From this and other properties it may be considered that the soil is subjected to the anionic solvation and eluviation, and consequently, is not a product of podzolization. The soil is infertile because of the strongly acid reaction and the low base status.
