Fig. 3. Clay content, bulk density, cone index, and saturated hydraulic conductivity (K_sat) of the soils measured in 1990 and 2000. No data of clay content is available for SF1 and SF2 in 1990. The K_sat value was measured by the constant-head method in 1990, and by falling-head method in 2000 (VF: virgin forest, SF: soybean field).