“一提一补”水价改革对作物单产的影响分析*——基于中介效应分析法和倍差法的实证研究

THE ANALYSIS OF "COLLECT THEN REFUND" WATER PRICING MECHANISM′ S EFFECT ON CROP YIELD PER UNIT*——BASED ON MEDIATION EFFECT AND DID MODEL

关键词:  水价一提一补中介效应倍差法水价改革

Key words:  water price  Collect then Refund  mediation effect  DID model  water pricing reform

摘要:

［目的］20世纪80年代以来，水价政策逐渐成为缓解水资源供给矛盾的重要手段。然而，由于可能存在损害农户利益的风险，水价政策一直饱受学术界的争议，政策制定者一直在探索一种“双赢”的水价调控机制。河北省衡水市桃城区为缓解常年超采地下水的现状，于2005年8月首创“一提一补”水价调控机制，以期实现农户利益和资源保护之间的共赢。［方法］文章利用河北省衡水市桃城区332户农户调研数据，利用中介效应和倍差法模型，实证分析“一提一补”水价改革对当地主要3种作物小麦、玉米、棉花单产的影响，从单产角度对“一提一补”水价改革的政策效果进行评估。［结果］“一提一补”对玉米和棉花单产的影响并不显著，但是对小麦单产会有显著的负面影响且用水量在其中起到完全中介作用，但由于技术进步的存在，农业机械化等因素可以抵消这些负面影响，促进单产提高。［结论］基于实证结果，该文提出了相关部门需要探讨未来进一步提价可能性、推广农业机械化的使用以及加大高产品种和技术的研发力度等政策建议。

Abstract:

Water Pricing mechanism has played an important role in alleviating water supply and demand since1980s. However, due to its′ possible probability of damage farmers′ benefit, Water Pricing mechanism has been suffered academic controversial for a long time and the policy marker has been exploring the "win win" Water Pricing mechanism. The local government of Taocheng district, Hebei province has originally proposed "Collect then Refund" Water Pricing Mechanism at Aug., 2005 which aimed to solve the urgent situation of perennial groundwater overexploitation and achieved a win win results between farmers′ interests and resource protection. Based on the household questionnaire data of 332 households in Taocheng district, Hebei province, the Mediation effect and DID model were adopted to identify the impact of"Collect then Refund" Water Pricing Mechanism on main crops′ including wheat, maize and cotton yield , and to estimate and to evaluate the effect of "Collect then Refund" on the crops′ per unit yield. The empirical result showed that the"Collect then Refund" mechanism′ s had not a significant effect on corn′s and cotton′s yield per unit, while it had a significantly negative effect on wheat′ s yield, the reason was that the irrigation water consumption had a total mediation function in the process of "Collect then Refund" Water Pricing mechanism. Due to technical progress, the above negative influence could be offset and the wheat yield still increased. Based on our research findings, this research proposes the policy recommendations including the future increase irrigation water price, promotion agricultural mechanization and strengthen R&D investment of high yielding varieties and technologies.