“稻虾共养”生态农业模式的化肥减量效应研究——基于倾向得分匹配(PSM)的估计

为应对化肥施用量居高不下引发的农业面源污染,长江中下游地区稻虾共养模式应运而生。基于课题组于2018年7～8月在江苏、湖北两省获取的509份样本农户数据,利用倾向得分匹配法(PSM),探讨稻虾共养模式的化肥减量效应是否存在及效应大小。结果表明:(1)采纳稻虾共养模式的农户确实存在显著的化肥减量效应,平均为其减少716.895元/ha,这为政府试图通过推广稻虾共养模式减少农业面源污染的合理性提供了佐证;(2)经过PSM方法处理后采纳稻虾共养模式农户的平均处理效应为-662.364,进一步证实稻虾共养模式的化肥减量效应存在且显著,而OLS模型回归高估了其化肥减量效应。基于此,我们认为稻虾共养模式应得到重点推广,并积极发展村庄中的能人以加强其带头示范作用。

Study on the Effect of Chemical Fertilizer Reduction in the “Shrimp and Shrimp Co-cultivation” Ecological Agriculture Model:Estimation Based on Propensity Score Matching (PSM)

Abstract：In order to cope with the agricultural non-point source pollution caused by the high application rate of chemical fertilizers, the rice-shrimp co-cultivation model in the middle and lower reaches of the Yangtze River came into being. Based on the data of 509 sample households obtained by the research team in Jiangsu and Hubei provinces from July to August 2018, the propensity score matching method (PSM) was used to explore the existence and effect of fertilizer reduction effect of rice-shrimp co-cultivation model. The conclusions of the study show that: (1) Farmers adopting the rice-shrimp co-feeding model do have significant fertilizer reduction effects, with an average reduction of 716.895 yuan/ha, which is the government’s attempt to reduce agricultural non-point source pollution by promoting the rice-shrimp co-feeding model. Rationality provides evidence; (2) The average treatment effect of fertlizer application farmers adopting the rice-shrimp co-feeding model after treatment with PSM method is -662.364, further confirming that the fertilizer reduction effect of rice-shrimp co-feeding mode exists and is significant, while the OLS model returns high. Estimated its fertilizer reduction effect. Based on this, this paper believes that the rice-shrimp co-feeding model should be promoted and actively developed in the village to strengthen its leading role.