関東ロームの構成粒子特性

1) The samples presented here a) Volcanic ash soil i) the northern Kanto Loam (Diluvial, sampled at Utsunomiya Univ. farm, depth 15, 100, 150, 180, 240, 300cm by horizons) ii) the southern Kanto Loam (Diluvial, sampled at Tokyo Agri. Univ. farm, depth 0, 30, 43, 80, 140cm) b) Non-volcanic ash soil i) Iwatagahara red-yellow soil (Diluvial, sampled at Shizuoka Univ. farm, depth 0, 40, 70cm) ii) Tsuruoka brown forest soil (Tertiary, sampled, at Tsuruoka, depth 0, 22, 40, 65cm).<BR>2) The determination: mineral and clay mineral composition, specific gravity of soil, specific surface area, mechanical composition, relationships between defloculate agent and soil, stability of aggregate, total carbon, total nitrogen, free iron content, percentage lime saturation, cation ex change capacity, exchangeable calcium, exchangeable magnesium, pH of soil, humus content.<BR>3) The determined values of specific gravity of a soil are variable and the variation is larger among samples of the same volcanic ash soil than among those of the samenon-volcanic ash soil. As volcanic ash soil particles have porous structure, a few change of conditions with which the air is removed effect very severly.<BR>4) According to the B. E. T. theory, specific surface area is determined. It was about 330m²/g, in the Kanto Loam (fresh soil) and about 80m²/g in non-volcanic ash soil, 330m²/g in as much as that of bentonite and this makes one think of internal layer absorption of allophane particles its value does not change largely by drying practice (air dry, 50°C, 105°C oven dry).<BR>5) Stability of aggregate. By comparing water stable aggregate of air dry soil with that of the fresh soil through sieving in water, we found that aggregates of surface soil are combined with humus and subsoil aggregates with water, and that non-volcanic ash subsoil aggregates disperse easily when air dried aggregates are immersed in water, but volcanic ash subsoil aggregate are stable. These phenomena are explained, by means of the conbination of non-free water, particle size distribution, soil structure, swelling and shrinkage.<BR>6) The relationships between clay content and non-free water (pF 4.2 retension water) are clear but it was found that the clay content is not directly related to the permeability.