Characteristics of soil moisture variation in different land uses in a small catchment on the Loess Plateau, China

Abstract

Understanding how soil moisture changes under different land uses is essential to ensure effective utilization of water and soil resources and to facilitate vegetation restoration in arid and semiarid ecosystems. Soil moisture content in the 0 to 160 cm soil profile in a sloping cropland, terraced cropland, jujube (Ziziphus jujuba) orchard, and natural grassland was monitored in a small catchment on China's Loess Plateau, using EC-5 soil moisture sensors, during the 2014 and 2015 growing seasons (May to October). The results demonstrated that the vertical distribution and seasonal variation in soil moisture and the characteristics of soil water storage under different land uses varied in years with different hydrological characteristics. During the persistent drought after heavy rainfall in 2014, the soil moisture loss rate under the terraced cropland increased slowly with time and was much lower than under the other land use types. In the drought year (2015), water storage in the 0 to 160 cm depth range under the terraced cropland was 36.9, 25.1, and 11.7 mm higher than that associated with the sloping cropland, jujube orchard, and grassland, respectively. In the normal year (2014), the average moisture content in the 0 to 60 cm depth range in the jujube orchard was 2.9%, 3.7%, and 4.5% lower than that of the sloping cropland, terraced cropland, and grassland, respectively (p < 0.05). During the persistent drought, the soil moisture loss rate from the jujube orchard was the highest and increased rapidly as the drought continued. In the drought year, the effective soil water storage in the 0 to 160 cm soil layer in the jujube orchard accounted for only 35.04% of the potential total soil water storage. The above findings are useful for making choices about water management and optimal utilization of land resources in the loess hilly region and potentially in other arid and semiarid areas.