Dynamics of soil moisture depletion and replenishment in different land use types of the Loess Tableland

Abstract

Soil moisture has large impacts on agricultural production and regional ecosystems. The Loess Tableland was selected as the study area, and the characteristics of soil moisture in different land use types were measured and analyzed from March to October 2012. The objectives of this study were to characterize the dynamic changes in soil water, determine the soil moisture depletion and replenishment depths, and compare the differences in water consumption under the different land uses. The results showed that: (1) Soil moisture content recorded in the 0-600 cm layer in a 7鄄year鄄old apple orchard was the highest, followed by that in a corn field, wheat field, and a 17鄄year鄄old apple orchard. Soil moisture contents in different land use types had the same variation trends as precipitation during the observation period, but their responses lagged changes in precipitation. (2) Soil moisture variation declined with increasing soil depth in different land use types. The variation in surface soil water content was greater than that of deep soil water content because the surface layer (0-100 cm) was influenced by multiple processes, including rainfall infiltration, soil evaporation, and plant root water uptake. Soil moisture was less affected by outside conditions as soil depth increased; therefore, soil moisture tended to be relatively stable. In addition, because of complicated functions of plant growth regulation and local phenological