粮食生产与水资源空间错配缘由：基于比较优势理论探究

为探究我国粮食生产与水资源空间分布错配原因，构建测算指标体系综合评价各地区水资源承载力，测算农业用水压力评估地区粮食生产与水资源空间分布的错配程度；基于比较优势理论视角利用面板数据进行实证检验，探究粮食生产与水资源空间分布错配产生的可能原因。结果表明:1)从测算结果看，我国31省2003—2018年的粮食生产与水资源空间分布存在错配，以东北区、黄淮海区、华南区和西北区错配较为严重。2)从基准模型回归结果看，土地优势、劳动优势、资本优势对区域农业用水压力的正向推动作用超过水资源优势对区域农业用水压力的负向作用，使得粮食生产综合比较优势加大了区域农业用水压力，在类似的市场与政策环境下粮食生产与水资源空间分布错配的内在原因正是上述累加作用的结果；采用分位数回归检验结果稳健性，发现在农业用水压力极大和极小区域粮食生产比较优势对农业用水压力的加剧作用并不明显，其余分位点处均显著。3)从调节效应模型结果看，农业用水效率在粮食生产比较优势对农业用水压力的影响中具有负向调节作用，分样本回归发现农业用水压力较高区域农业用水效率调节作用更大，表明较高的农业用水效率能够有效缓解区域粮食生产比较优势对粮食生产与水资源空间分布错配的影响，且在农业用水压力较高的区域缓解作用更加明显。因此，优化粮食生产与水资源空间匹配程度，加大粮食生产布局中水资源要素约束权重，分区域提升粮食生产用水效率，有利于保障粮食安全与水资源的可持续利用。

Causes of spatial mismatch between grain production and water resources: Based on the theory of comparative advantage

To explore the causes of spatial mismatch between grain production and water resources in China, a measurement index system was constructed to comprehensively evaluate the carrying capacity of water resources in each region and measure the degree of spatial mismatch between grain production and water resources in the evaluation area of agricultural water pressure. Additionally, from the perspective of comparative advantage theory, a panel data was used to conduct empirical tests and explore the possible causes of the spatial mismatch between grain production and water resources. The results show that: 1)According to the calculation results, the spatial distribution of grain production between water resources in 31 provinces of China from 2003 to 2018 is mismatched, and the spatial distribution mismatch between grain production and water resources in north East China, Huang-Huai-Hai region, South China and Northwest China is more serious. 2)According to the regression results of the benchmark model, the positive effect of land advantage, labor advantage and capital advantage on regional agricultural water pressure exceeds the negative effect of water resource advantage on regional agricultural water pressure, which makes the comprehensive comparative advantage of grain production increase the regional agricultural water pressure. Under the similar market and policy environment, the internal cause of the spatial distribution mismatch between grain production and water resources is the result of the above accumulative effects. Quantile regression is adopted to test the results. It is found that the intensification effect of grain production comparative advantage on agricultural water pressure is not obvious in the regions with the maximum or minimum agricultural water pressure, but is significant in the other sub-loci. 3)According to the results of the moderating effect model, agricultural water efficiency has a negative moderating effect on the impact of comparative advantage of grain production on agricultural water pressure. Sample regression shows that agricultural water efficiency has a greater regulating effect in areas with higher agricultural water pressure, indicating that higher agricultural water efficiency can effectively mitigate the impact of regional comparative advantage of grain production on the spatial distribution mismatch between grain production and water resources, and the mitigating effect is more obvious in areas with higher agricultural water pressure. Therefore, based on the research results, this study puts forward three suggestions, e. g. optimizing the spatial distribution mismatch degree of grain production and water resources, increasing the constraint weight of water resources factors in grain production layout, and improving water efficiency of grain production by region, to ensure grain security and sustainable use of water resources.