The results of the falsification test.

The sustainable development of agriculture hinges on effective fertilizer management, and China’s experience with chemical fertilizer overuse highlights the challenges and opportunities in this domain. This study examines the impact of agricultural subsidy policy on chemical fertilizer use across 2319 counties from 2012 to 2022. By treating the “Action Plan for Organic-Substitute-Chemical-Fertilizer (OSCF) for Fruits, Vegetables and Tea” as a quasi-natural experiment, this study uses a Double Machine Learning model to analyze its effects on fertilizer use and the underlying mechanisms, considering technical and scale efficiency as mediating variables. The findings reveal that the OSCF policy has a significant negative effect on chemical fertilizer use, primarily by enhancing both technical and scale efficiency. This study further reveals regional heterogeneity in the policy’s effectiveness. The results imply that while the impact of the OSCF policy is generally beneficial, it is shaped by regional economic development, agricultural production structure and initial level of fertilizer use. This highlights the importance of tailored policy instruments to address regional disparities in agricultural practices and targeted strategies to maximize the OSCF policy’s impact on sustainable agricultural development. This study provides valuable insights for policymakers and farm managers to enhance the sustainability of agricultural practices.

农业的可持续发展有赖于高效的肥料管理，而中国在化肥过量施用方面的实践凸显了该领域的挑战与发展机遇。本研究以2012—2022年全国2319个县域为研究样本，考察农业补贴政策对化肥施用的影响效应。随后，本研究将《果菜茶有机肥替代化肥行动计划》（Organic-Substitute-Chemical-Fertilizer, OSCF）作为准自然实验（quasi-natural experiment），采用双重机器学习（Double Machine Learning）模型，以技术效率与规模效率作为中介变量（mediating variables），分析该政策对化肥施用的作用效果与内在传导机制。研究结果表明，OSCF政策对化肥施用存在显著负向抑制作用，其核心传导路径为提升农业生产的技术效率与规模效率。本研究进一步揭示了该政策实施效果的区域异质性（regional heterogeneity）：尽管OSCF政策的整体影响呈积极态势，但其政策效应受区域经济发展水平、农业生产结构与初始化肥施用水平的共同塑造。这一结论凸显了制定差异化政策工具以应对农业生产实践中的区域差距、并采取针对性策略以最大化OSCF政策对农业可持续发展的促进作用的必要性。本研究可为政策制定者与农业经营主体优化农业生产可持续性提供极具价值的决策参考。