The Dependence of Soil Water Uptake and Release Upon the Applied Pressure Increment

Two independent methods and three porous materials were used to ascertain whether or not the soil water content‐capillary pressure relation (soil water characteristic) depends on the rate at which soil water redistributes with applied capillary pressure increment. In one method small, uniform samples were subjected to known capillary pressures by means of a porous plate. The other method involved rotating 100‐cm long samples end‐to‐end at different rates and measuring the water content and capillary pressure distributions at equilibrium when the samples were vertical. The data from two soils, a silt loam and a sand, and a sandstone support the conclusion that the equilibrium water content depends on the size of the applied capillary pressure increment.