Distribution and characters of soil dry layer in north Shaanxi Loess Plateau Moisture dynamics of soil dry layer and water-restoring effects of alfalfa (Medicago sativa)-grain crop rotation on soil dry layer in alfalfa farmlands in Mountainous Region of Southern Ningxia Dynamics of soil moisture depletion and replenishment in different land use types of the Loess Tableland Growth of Caragana korshinskii and Depletion Process of Soil Water in Semi-Arid Region