Abstract
Soil profile research and analyses of soil physical and chemical properties were conducted for the soils under Hinoki (Chamaecyparis obtuse) plantation and broad-leaved forest in the basin of Tsuzura River in Shimanto Town, Kochi Prefecture, Japan. The soil under Hinoki plantation had no O horizon and contained large number of gravels in upper part of the profile, which was suggested that the soil under Hinoki plantation was influenced hardly by soil erosion. Total carbon and nitrogen content and CEC in the topsoil under Hinoki plantation were lower than those under broad-leaved forest. Macro-porosity was higher and micro-porosity was lower in topsoil and subsoil under Hinoki plantation than those under broad-leaved forest. There was high correlation between micro-porosity and liquid phase rate. As making thin section from the topsoil, soil micro-morphology in each soil was observed with polarizing microscope. Soil particles mainly existed to form peds in broad-leaved forest. On the other hand, in soil under Hinoki plantation, the amount of peds was comparatively small, and micro-structure consisted of peds and single grains. Crumbs in the soil under broad-leaved forest were aggregate of minute peds, which contained many small voids, while crumbs in the soil under Hinoki plantation were compact with low amounts of small interaggregate voids. It was supposed that such differences of quantity and quality of peds between the soils under Hinoki plantation and broad-leaved forest caused differences of soil physical properties.
