Policy Simulation Laboratory, Zhejiang University, 310058 Hangzhou, China.
China Center for Economic Studies, School of Economics, Fudan University, 200433 Shanghai, China.
Proc Natl Acad Sci U S A. 2018 Jul 3;115(27):7010-7015. doi: 10.1073/pnas.1806645115. Epub 2018 Jun 18.
Understanding the reasons for overuse of agricultural chemicals is critical to the sustainable development of Chinese agriculture. Using a nationally representative rural household survey from China, we found that farm size is a strong factor that affects the use intensity of agricultural chemicals across farms in China. Statistically, a 1% increase in farm size is associated with a 0.3% and 0.5% decrease in fertilizer and pesticide use per hectare ( < 0.001), respectively, and an almost 1% increase in agricultural labor productivity, while it only leads to a statistically insignificant 0.02% decrease in crop yields. The same pattern was also found using other independently collected data sources from China and an international panel analysis of 74 countries from the 1960s to the 2000s. While economic growth has been associated with increasing farm size in many other countries, in China this relationship has been distorted by land and migration policies, leading to the persistence of small farm size in China. Removing these distortions would decrease agricultural chemical use by 30-50% and the environmental impact of those chemicals by 50% while doubling the total income of all farmers including those who move to urban areas. Removing policy distortions is also likely to complement other remedies to the overuse problem, such as easing farmer's access to modern technologies and knowledge, and improving environmental regulation and enforcement.
理解过度使用农用化学品的原因对中国农业的可持续发展至关重要。利用一项具有全国代表性的中国农村家庭调查，我们发现，农场规模是影响中国农场农用化学品使用强度的一个重要因素。从统计学上看，农场规模每增加 1%，化肥和农药的使用量（<0.001）就会分别减少 0.3%和 0.5%，农业劳动生产率几乎会增加 1%，而农作物产量仅会减少 0.02%，但这一减少并不具有统计学意义。利用来自中国的其他独立收集的数据来源和对 20 世纪 60 年代至 2000 年代 74 个国家的国际面板分析，也发现了同样的模式。虽然在许多其他国家，经济增长与农场规模的扩大有关，但在中国，土地和移民政策扭曲了这种关系，导致中国的农场规模一直保持较小。消除这些扭曲将使农业化学品的使用减少 30-50%，这些化学品对环境的影响减少 50%，同时使包括转移到城市地区的农民在内的所有农民的总收入增加一倍。消除政策扭曲也可能补充解决过度使用问题的其他措施，例如，减轻农民获取现代技术和知识的难度，并改善环境监管和执法力度。
