氮磷平衡视角下农户粮食生产环境效率分析——基于DEA-CLAD两阶段模型

Study on environmental efficiency of farmers’grain production:based on the two-phase modeling of DEA-CLAD

科学评估粮食生产的环境效率并研究其影响因素,对保障粮食生产的可持续发展具有重要理论和现实意义。从粮食生产氮磷平衡的视角,将氮和磷的盈余作为"非期望产出",构建非径向SBM方法的农业环境效率评估模型。在此基础上,在扰动项不服从正态性和同方差性假设的情况下,采用更加稳健的CLAD模型来代替传统的Tobit模型,构建DEA-CLAD的两阶段模型。利用2004—2016年浙江省籼稻种植农户的地块层面的数据,对籼稻生产的环境效率进行测量,并对其影响因素进行实证估计。研究结果表明,浙江省籼稻生产历年环境效率处于波动之中,平均环境效率为0.563,有较大提升空间;粮食价格、化肥价格和农药价格是籼稻生产环境效率的主要影响因素,粮食价格、化肥价格对环境效率有正向显著的影响,而农药价格对环境效率的影响为负;粮食生产环境效率还受到劳动力价格、土地成本、补贴和农户年龄等市场因素、政策和农户特征多方面的影响。

It is of great theoretical and practical significance to evaluate the environmental efficiency of grain production and analyze its influencing factors for ensuring the sustainable development of grain production.From the perspective of the material balance principle,this paper constructs an agricultural environmental efficiency evaluation model based on the SBM method,in which the nitrogen and phosphorus are treated as the"unexpected output".Under the condition that the disturbance term does not obey the assumption of normality and homoscedasticity,a two-stage model of DEA-CLAD model is used to replace the traditional Tobit model.Based on the data of plot level of indica rice farmers in Zhejiang Province from 2004 to 2019,the environmental efficiency of indica rice production is measured and the influencing factors are estimated empirically.The results showed that:1)the environmental efficiency of indica rice production in Zhejiang Province has been fluctuating over the years,with an average environmental efficiency of 0.563,which has a large space for improvement.2)Grain price,chemical fertilizer price and pesticide price are the main influencing factors of environmental efficiency of indica rice production.Grain price and chemical fertilizer price have positive and significant effects on environmental efficiency,while pesticide price has negative effects on environmental efficiency.3)The environmental efficiency of grain production is also affected by market factors,policies and farmers’characteristics,such as labor price,land cost,subsidies and farmers’ages.