Correlating grain yield with irrigation in a spatio-temporal context on the North China Plain.

Irrigation plays a crucial role in enhancing agricultural productivity. The spatiotemporal variability and correlation between historical irrigation and grain yield not only illuminate existing challenges in irrigation, but also offer valuable insights for formulating effective irrigation strategies, which have been previously overlooked. Taking the North China Plain (NCP) as a case study, this study aims to elucidate regional divergence patterns and the dynamic evolution of the spatiotemporal relationship between grain yield and irrigation through time series analysis, GIS spatial analysis, and geographically weighted regression (GWR). The findings reveal that grain yields are higher in the northern regions of NCP compared to the southern regions, with significant variations among prefecture-level cities; maize yields slightly surpass wheat yields. Moreover, there has been a noticeable decrease in irrigation across approximately 49 % of the areas since 2004. Spatial autocorrelation analysis indicates clear spatial aggregation for both grains yields and irrigation. The coupled correlation between wheat yield and effective irrigation has shown a slight increase from 1990 to 2015, while that of maize has significantly decreased. The positive impact of irrigation on grain yield has nearly vanished since 2002. It is recommended to implement sprinkler irrigation in low-yield, low-irrigation areas in the south; deficit irrigation and water-saving technologies may benefit regions with medium yield and negative correlation with irrigation in central parts; maintaining current irrigation strategies is suggested for high-yield and high-irrigation regions. Additionally, relying solely on irrigation to boost yields is unsustainable; it is critical to adopt a combination of agricultural management practices along with planting high water-utilization efficient crop varieties. This study underscores the significance of developing rational irrigational strategies based on a comprehensive understanding of the intricate relationship between irrigation and grain yields-ensuring food security while sustaining agricultural water utilization.