绿色农业补贴政策的环境效应和经济效应——基于世行贷款农业面源污染治理项目的断点回归设计

The Environmental and Economic Effects of Green Agricultural Subsidy Policies:A Regression of Discontinuity Design Based on Agricultural Non-point Source Pollution Control Programs with the World Bank’s Loan in Guangdong Province

针对高强度的化肥施用和面源污染问题,广东省实施了世行贷款农业面源污染治理项目。本文以此为契机,选取受项目干预的村庄进行拟随机实验设计,考察绿色农业补贴政策的环境效应和经济效应。本文利用地块调查微观数据,通过模糊断点回归设计估算了绿色农业补贴政策对肥料投入环境效率和肥料生产率的局部平均处理效应。与政策制定者预期以及前人研究观点不同的是,本文研究发现绿色农业补贴政策降低了肥料投入环境效率和肥料生产率。在加入协变量、采用三角核函数、选择最优带宽的情况下,绿色农业补贴政策对肥料投入环境效率和肥料生产率的局部平均处理效应显著为负。但不能依此否定该政策,因为在绿色农业技术推广早期阶段,利用补贴政策可以引导要素投入和优化要素配置,提高要素使用水平。可取的政策选择是使绿色农业补贴政策和市场化机制有机衔接,即在绿色农业技术推广早期阶段,通过绿色农业补贴政策提高技术采纳率,随后逐步淡化绿色农业补贴政策,增强市场机制的引导作用。

To solve the problem of high intensity chemical fertilizer application and non-point source pollution,Guangdong Province has implemented the agricultural non-point source pollution control programs with the World Bank’s loan.Taking this as an opportunity,this article investigates the environmental and economic effects of formula fertilizer subsidy policies.The villages which are intervened by the projects are selected and a "quasi random experiment" is designed.In the experiment,the farmers joining in the projects and farmers without j oining in the projects are selected as "treatment group" and "control group",respectively.The study estimates the local average treatment effect of green agricultural subsidy policies on environmental efficiency and fertilizer productivity by using the micro data of land survey and a fuzzy regression discontinuity design. Contrary to the expectation of policymakers and previous studies,this study finds that green agriculture subsidy policies have reduced the environmental efficiency of fertilizer input and fertilizer productivity.In the case of adding covariates in the model,using the trigonometric kernel function and selecting the optimal bandwidth the local average treatment effect of green agricultural subsidy policies on environmental efficiency and fertilizer productivity is significantly negative.But the policies should not be denied,because in the early stage of green agricultural technology extension,using subsidy policies has optimized factor inputs and improved the utility level of the factors.In the early stage of technology extension,green subsidy policies should be used to improve the technology adoption rate,and then be weakened gradually to enhance the role of the market mechanism.In this way green subsidy policies and the market mechanism can be linked organically,which is a desirable policy choice.