Study of soil water retention in Horqin Sand Land

Abstract

Soil water retention curve (SWRC) of 0 ~ 100 cm at typical sandy lands of Horqin Sand Land, such as grassland, fixed dune and mobile dune, were measured by the laboratory methods, and the variation of this parameter along with sandy types and soil depths were analyzed. At the same time, combined with soil moisture diffusivity studied previously, the soil unsaturated hydraulic conductivity was calculated. The results showed that (1) The SWRC of 0~100 cm in each sandy lands could be described better by the Gardner empirical equation θ = Ah-B. Soil water holding capacity is decreased in the order: grassland > fixed dune > mobile dune; When the soil water potential changes, the soil water content of mobile dune changes fastest, followed by fixed dune, and grassland changes slowest. In addition, Soil water holding capacity and soil moisture change rate vary considerably along with the type of sandy land and soil depth. (2) Soil unsaturated hydraulic conductivity is smallest for mobile dune, followed by fixed dune, and for grassland is largest. And soil unsaturated hydraulic conductivity decreases generally with soil depth increased. (3) Soil organic matter content and the particle size of <0.05 mm are conducive to water holding capacity, but bulk density and the particle size of 2~0.1 mm are discouraged to water holding capacity.