撥水性が森林土壌の水分特性曲線に与える影響

抄録

To determine the effect of water repellency on a water content(θ)-pressure head(Ψ) relationship of forest soil, we conducted transient experiments by using an undisturbed soil column of 4cm long and 11.3cm in diameter. This sample was collected at the ridge of Taga mountains of Northern Ibaraki. At the first experiment, water repellency was observed and pressure head increased from -300cm to -10cm with small change of water content. Then it took long time to complete absorption after pressure head reached to 0cm. On the other hand, applied water was absorbed into soil quickly at the second and third wetting experiments, and pressure head increased to 0cm with larger change of water content. Moreover, the change in pressure head from the initial value to 0cm was more quickly at the first wetting experiment than those at the second and third ones. These results indicated that water repellency caused more intense hysteresis of the θ-Ψ relationship.