灌溉水压力、供给弹性与粮食生产结构——基于变系数Nerlove模型

灌溉水稀缺性会限制粮食生产,也会同时诱致农业技术进步提高粮食供给弹性。基于2002-2017年27个省份面板数据,采用变系数Nerlove模型,通过探究灌溉水压力、价格变动及其交互作用对不同粮食作物产量的影响,分析灌溉水压力对粮食生产结构的综合作用。结果表明:（1）灌溉水压力对粮食生产结构的直接作用是提高玉米产量比例,降低其他粮食作物产量比例,降幅从大到小依次为水稻、薯类、豆类和小麦。（2）灌溉水压力对粮食生产结构的间接作用是使小麦、豆类和薯类的供给弹性更小,使水稻和玉米的供给弹性更大,有利于水稻和玉米产量占比的增加。（3）2002-2017年灌溉水压力不断增加,对粮食生产结构的综合作用是促进了玉米产量比例大幅增加、豆类和薯类产量比例显著下降;地区上,北方粮食主产区玉米和水稻产量比例显著增加,使水资源相对稀缺的北方地区粮食生产更耗水,该结论与“灌溉效率悖论”一致。

Irrigation water pressure,supply elasticity and grain production structure based on heterogeneous coefficient Nerlove model

Although scarcity of irrigation water restricts grain production, it can promote agricultural technology progress to increase supply elasticities of grain. To shed light on the comprehensive effect of irrigation water pressure on grain production structure, this paper explores the effects of irrigation water pressure, grain price changes and their interaction on the yields of different crops based on heterogeneous coefficient Nerlove model and panel data of 27 provinces from 2002 to 2017. The results show that: (1) The direct effect of irrigation water pressure on grain production structure is increasing proportion of corn yield and reducing proportions of other crops yields. Specifically, the magnitude of that impact is in a descending order from rice, potatoes, beans and wheat. (2) The indirect effect of irrigation water pressure on grain production structure is decreasing supply elasticities of wheat, beans and potatoes while making supply elasticities of rice and maize even larger, which contributes to the increase of proportions of rice yield and corn yield. (3) With growth of irrigation water pressure from 2002 to 2017, its comprehensive effect on grain production structure makes a significant increase in proportion of corn yield and a significant decrease in proportions of beans yield and potatoes yield. Regional analysis reveals an increase in yield proportions of maize and rice in main grain production areas of Northern China, leading to more irrigation water consumption in this region where scarcity of water is severer. And this finding of our paper is a support for "the paradox of irrigation efficiency".