Agricultural land green use efficiency benefits from appropriate urban–rural disparity: Evidence of nonlinear effects from China

• ALGUE shows a fluctuating rise, while URD follows a steady downward trend. • Narrowing URD significantly improves ALGUE. • URD affects ALGUE nonlinearly through multiple mediating mechanisms. • URD’s impact on ALGUE shows spatial spillovers and regional heterogeneity. Promoting the synergistic development of agricultural land use, economic output, and environmental benefits is a key task in China’s urban–rural integration and rural revitalization efforts. Despite growing research on agricultural land use efficiency and urban–rural inequality, limited attention has been paid to their nonlinear interactions, the mediating mechanisms linking them, and the potential spatial effects. Accordingly, the relationship between urban–rural disparity (URD) and agricultural land green use efficiency (ALGUE) remains insufficiently understood. This study examines the relationship between URD and ALGUE using provincial panel data spanning 2006 to 2020. Key findings include: (1) Spatial analysis reveals that ALGUE tends to be higher in eastern provinces and lower in the west, while URD shows the opposite spatial pattern. (2) A significant N-shaped nonlinear relationship is identified between URD and ALGUE, suggesting that moderate levels of URD enhance ALGUE, while both excessive and insufficient disparity impede it—offering a novel contribution to the existing literature. (3) The study further uncovers negative spatial spillover effects of URD on neighboring regions and highlights the mediating roles of industrialization and agricultural innovation. These findings underscore the need for stage-specific and regionally tailored policy interventions. Policymakers are encouraged to pursue balanced urban–rural development, avoid both excessive concentration and over-equalization of resources, and promote the cross-regional diffusion of green agricultural technologies to sustainably enhance agriculture land use efficiency.