Spatial-temporal coupling pattern between irrigation demand and soil moisture dynamics throughout wheat-maize rotation system in the North China Plain

Abstract

Irrigation water requirement (Iwr) and soil moisture (SM) are two essential metrics that guide scientific irrigation and agricultural water-saving practices. Although they have been extensively studied in the North China Plain (NCP), an exploration into their spatial-temporal coupling pattern remains absent. Here, the spatial-temporal coupling pattern underlying the variations of Iwr and SM across the winter wheat–summer maize rotation system within the NCP was elucidated from a geographic perspective, by developing a geo-statistic framework that integrated the global spatial autocorrelation, spatial hot-spot technique, geographically weighted regression, and the optimal parameters-based geographic detector. From 2000–2019, the Iwr and SM exerted a distinct geospatial heterogeneity. Winter wheat demonstrated a spatially descending gradient in Iwr from north to south, while the pattern in summer maize Iwr varied greatly across periods. Generally, winter wheat had a higher Iwr, while the geospatial pattern of summer maize Iwr displayed a greater variability. Spatial pattern of SM in 0–100 cm soil horizon exhibited an approximately inverse trajectory to that of Iwr, while SM in 100–200 cm horizon demonstrated a spatial staggered pattern. In most cases, there existed a notable negative coupling between Iwr and SM at 0–100 cm depth, but not universal at 100–200 cm. Nonetheless, a pronounced reciprocal enhancement mechanism between SM of two layers was confirmed. Between 2000 and 2019, a geospatial decoupling trend was detected between Iwr and SM throughout the NCP. Despite remaining universality, the pattern of high irrigation demand induced by soil moisture deficit was being weakened. Given these, climate-adaptive water-saving strategies were updated, which provide a new implication for regional agricultural water-saving practice and sustainable production.