The Impact of Grid-Scale Water Quality Variations on Crop Yields in China: A Regional Heterogeneity Analysis

Water quality is increasingly recognized as a key factor affecting agricultural yields, yet its impacts remain insufficiently understood at large and fine spatial scales. Existing studies often focus on localized effects or rely on field experiments, limiting their applicability to a single regional scale. In this study, we employ 0.5° grid data to systematically assess the effects of water quality on crop yields across China's major grain-producing regions, enabling fine-scale quantification of the relationship between water quality and yields. Our results indicate that different water quality indicators have varying degrees of impact on crop yields. We further explore regional heterogeneity in these impacts, uncovering spatial heterogeneity in the sensitivity of crop yields to water quality. These findings highlight the essential role of water quality in safeguarding agricultural output and underscore the strategic value of water quality management in improving resource-use efficiency and promoting sustainable agricultural development.