Spatiotemporal variability of soil–water content at different depths in fields mulched with gravel for different planting years

Abstract

Information about the spatiotemporal variability of soil–water content (SWC) is important for the management of soil resources. We present a case study of the temporal stability and variability of SWC at various depths in 32 × 32 m2 fields mulched with gravel for different planting years, a form of mulching that has been widely used by farmers in the loessial area of China for over 300 years, also, same analysis has been done on a bare land as CHECK. SWC was measured weekly from May to August 2013, May to August 2014, July to October 2015 and June to September 2016 in the 0–10, 10–30 and 30–50 cm layers. The higher SWCs of the gravel-mulched fields than the bare land decreased with depth and length of mulching, indicating the degradation of the fields. SWC was more variable in the surface soil, and the variability gradually decreased with depth. Locations representative of the field-mean SWCs were identified based on the stability of the SWC spatial patterns over time and along the soil profile in 2013. The mean SWCs at different soil layers for 2014, 2015 and 2016 were estimated by the measured SWCs of representative locations which were determined using the data of 2013, with high coefficients of determination ranging between 0.926 and 0.997. The monitoring of field-mean SWC over a long period of time from representative locations is thus feasible. Our results will provide a theoretical reference for monitoring SWC in a large scale from few observations and aid the management of gravel mulched field.