全量程（多分子层到饱和）土壤持水曲线变化规律初探

Changing Regularities of Soil Water Characteristic Curves in the Whole Range From Multimolecular Layer to Saturation

By using the methods of water extraction, freezing point depression and moisture absorption, three types of soil (i.e., sand, silt and clay) were tested to obtain the soil water characteristic curves in the whole range from multiolecular layer to saturation. It was found that the relationship between the absolute values of the soil water potential and water content could be expressed by a power equation. The absolute value of the soil water potential increases with the increasing of the clay particle content and salinity and the decreasing of the dry density of soils as water content is the same. It is related to the changing process of soil water. The absolute values of soil water potential in the dehydration process are greater than those in the hygroscopic process. The hysteresis of the soil water characteristic curves in hygroscopic process could be explained by the theory of overlapping hydrate film.