Spatial and temporal dynamics in soil water storage under different use types of sloping fields: a case study in a highland region of southern China
南方丘陵区不同坡地利用方式土壤水分动态

Soil water heterogeneity has significant effects on many hydrological processes and soil development processes, and research on spatial and temporal heterogeneity in soil water content is important for understanding and forecasting soil water processes. In situ monitoring of soil water content changes in sloping fields under different use types were carried out in a highland region of southern China using time domain reflectometry (TDR). There was a significant variation in soil water storage among sloping fields under different use types, and soil water storage under Eucommia ulmoides plantation was found to be the highest, followed by non-cultivated sloping field and the lowest by cultivated sloping field. There was also a significant seasonal variation in soil water storage, with the average soil water content being higher during the non-growing season than during the growing season. In addition, there was a similar pattern of change in soil water profiles under different types of sloping field use in either wet or dry seasons. A negative relationship was observed between soil water storage and solar radiation and air temperature, but there was a positive relationship of soil water storage with rainfall, relative humidity and vapor pressure deficit. Thus, we can predict that soil moisture was strongly influenced by a combination of several meteorological factors, among which the most important factor was precipitation and the next important factor was temperature. After rain, soil water loss rate of the three sloping field types had a significant hyperbolic relationship with drought durating days (P<0.05), but soil water storage had a significant negative linear relationship with drought durating days (P<0.05). Furthermore, soil water loss was found to vary with the period of drought duration as well as with soil depth.