增产加剧污染？——基于粮食主产区政策的经验研究

本文以粮食主产区政策为切入点,将2004年全国设立13个粮食主产区视为一次准自然实验,利用双重差分法,考察了粮食主产区政策对化肥面源污染的影响及其作用机制。研究主要发现:①基础回归分析表明,粮食主产区政策对化肥面源污染具有显著的削减效应,尤其针对氮污染排放量;②影响机制分析表明,上述削减效应主要得益于粮食种植规模的扩大,即通过发挥粮食作物生产的规模效应以降低化肥污染排放量;③异质性分析表明,促进劳动力转移与扩大土地经营规模有助于粮食主产区发展适度规模经营以获取规模效应,进而实现对化肥面源污染的削减效应。据此,本文研究为粮食主产区内不存在增产加剧污染的可能性提供了经验性证据,也为在粮食安全的目标下兼顾农业发展与生态环境保护提供了有益的政策启示。

The More Grain Production,the More Fertilizers Pollution? Empirical Evidence from Major Grain-producing Areas in China

China’s agricultural system has been confronted with contradictions and conflicts between agricultural development and eco-environmental protection for a long time.In particular,the problem of non-point source pollution of chemical fertilizers in the major grain-producing areas has been receiving much attention.Focusing on the policies in major grain-producing areas,this article regards the establishment of 13 major grain-producing areas in China in 2004 as a quasi-natural experiment,and systematically examines the impact of policies in major grain producing-areas on the non-point source pollution of chemical fertilizers and its mechanism by using a difference-in-differences method.The main conclusions of this study are as follows.First,the basic regression analysis shows that the policies in major grain-producing areas have a significant reduction effect on non-point source pollution of chemical fertilizers,especially for nitrogen pollution emissions.Second,the impact mechanism analysis shows that the above reduction effect is mainly due to the expansion of grain plantation scale,that is,the scale effect of grain crop production can be brought into play to reduce the emission of chemical fertilizers pollution.Third,the promotion of labor transfer and the expansion of land management scale are conducive to the development of moderate scale operation in major grain-producing areas to obtain the scale effect,which helps to generate the reduction effect on the non-point source pollution of chemical fertilizers.Therefore,this study argues that the policies in major grain-producing areas can contribute to achieving a win-win goal of agricultural development and eco-environmental protection.To a certain extent,the results not only provide empirical evidence for resolving the contradictions and conflicts between agricultural development and eco-environmental protection,but also provide policy implications in major grain-producing areas for promoting agricultural development and improving eco-environmental protection underthe goal offood security.