农业机械化的环境效应——来自农机购置补贴政策的证据

The Environmental Effects of Agricultural Mechanization: Evidence from Agricultural Machinery Purchase Subsidy Policy

本文基于中国县级农业生产数据以及卫星遥感数据,从农机购置补贴政策实施的视角,依托该政策推广的准自然实验特征,利用双重差分模型识别了农机购置补贴政策对农业机械化水平和污染性农业生产行为的影响及其作用机制,回答了农业机械化如何影响生态环境的问题。研究发现,农机购置补贴政策显著提高了试点县的农业机械化水平,政策对不同污染性农业生产行为的影响存在差异,且具有一定滞后性。具体地,农机购置补贴政策显著减少了当年及下一年的地膜使用量,增加了下一年的秸秆焚烧火点数目,但对化肥施用量和农药使用量的影响不显著。机制分析表明,农机购置补贴政策通过扩大粮食播种面积占比以及促进农业劳动力转移,改变了农户使用污染性投入要素和处理农业生产废弃物的方式,从而对生态环境产生了相应的影响。

Based on China’s agricultural production data at the county level and satellite remote sensing data, from the perspective of the implementation of the agricultural machinery purchase subsidy policy, this article takes the quasi-natural experimental characteristics of the policy as exogenous shocks of agricultural mechanization and uses the Difference-in-differences(DID)approach to measure the impacts of agricultural machinery purchase subsidy policy on polluting agricultural production behaviors and its mechanisms. The results show that the agricultural machinery purchase subsidy policy has significantly improved the level of agricultural mechanization, and the impacts of the policy on polluting agricultural production behaviors are different and with a certain lag. Specifically, the policy has significantly reduced the use of plastic film in the current year and the next year, and increased the number of straw-burning points in the next year after the policy started, but had no significant impacts on the use of chemical fertilizer and pesticide. The mechanism analysis shows that the policy has changed the way farmers used polluting inputs and treated agricultural production waste by expanding the proportion of grain sown area and promoting the outflow of agricultural laborforce, which has a corresponding impacton theecological environment.