Regional Disparities and Spatiotemporal Evolution of Non-Point Source Pollution Loads from Crop Straw Fertilizer Utilization in China under Rural Revitalization

Abstract

Crop straw recycling as organic fertilizer is widely promoted in China to curb open burning and enhance nutrient cycling, yet its potential contribution to agricultural non-point source pollution remains insufficiently quantified. Using provincial panel data for 31 regions during 2017-2024, this study estimates pollution loads associated with crop straw fertilizer utilization, focusing on total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD). Nationally, TN, TP, and COD loads show a mild but persistent increase over the study period, with COD contributing the largest share. Dagum Gini decomposition indicates that interprovincial inequality is substantial and relatively stable, and that between-region differences account for most of the overall disparity, while within-region inequality is particularly pronounced in the eastern region. Kernel density estimation suggests a consistently right-skewed distribution, with most provinces remaining at low load levels but a small set of provinces forming a high-load tail that becomes slightly more prominent in recent years. Global Moran’s I is positive but statistically insignificant, implying weak nationwide spatial clustering; however, local indicators of spatial association reveal stable hotspot and coldspot provinces. Spatial Markov analysis further shows strong state persistence, while high-neighborhood contexts are associated with more active transitions between higher-load states. Policy implications emphasize integrated straw management and regionally differentiated control strategies.