Spatiotemporal dynamics of soil moisture and matric potential under different land covers at an agricultural site

Knowledge of the spatiotemporal patterns of soil moisture content ( θ ) and soil matric potential ( ψ ) is important for understanding landscape hydrological processes and agricultural management. Previous studies mostly focused on θ , while relevant studies on the spatiotemporal characteristics of ψ were still limited. In this study, the spatiotemporal patterns of θ and ψ were jointly investigated by one-year θ and ψ data, which were collected at 30 cm and 60 cm along a 100-m transect under cropped conditions and a 20-m transect under bare surface conditions in the North China Plain. The results showed that the spatial mean-variance relationship for both θ and ψ displayed upward convex relationships, and vegetation tended to reduce the spatial variability in θ and ψ through root water uptake processes, particularly at deeper soil layers (60 cm), suggesting that the spatial variability in θ and ψ at field scales depended on both moisture and land cover conditions. Moreover, the temporal stability analysis (TSA) revealed that the temporal stability of θ and ψ was different at the study site, which attributed to the influence of vegetation. The correlations between soil texture and the mean relative differences of θ and ψ further confirmed the effect of vegetation at field scales. Due to the different spatial patterns of θ and ψ , the representative sites for monitoring areal average θ and ψ differed, although the results demonstrated the usefulness of the TSA for selecting representative sites for both θ and ψ . Finally, the wavelet coherency analysis was employed to examine the spatial patterns of θ and ψ under cropped conditions. The results revealed that the intra-seasonal spatial stability of θ and ψ was strongly influenced by their large-scale (>8 m) correlations, which were more significant at 30 cm in spring and at 60 cm in summer. This study underscores the necessity to jointly investigate the interactions of θ and ψ with surrounding environments and provided insight into their spatiotemporal variations at field scales. • Spatial variability in θ and ψ depended on moisture and land cover conditions at field scales. • Vegetation impacted on temporal stability of θ and ψ was different at study site. • Wavelet coherence analysis was used to explain the inter-seasonal spatial patterns between θ and ψ .