城市扩张与耕地利用强度:工业发展与农户资源禀赋的调节效应

Urban expansion and arable land use intensity: adjustment effect of industrial development and farmers' resource endowment

城市扩张对耕地利用强度的影响关系到我国粮食安全。本文基于江苏省县级面板数据,分析城市扩张对耕地利用强度的影响机制,结合外部环境与内部禀赋因素,构建耕地利用强度影响模型,运用双向固定效应模型估计城市扩张对耕地利用强度的综合影响,并通过加入交互项的方式研究区域工业化水平与农户资源禀赋的调节作用。结果表明:第一,由于稀缺效应和资本效应的相互弥补抵消,城市扩张对耕地利用强度的影响在统计上不显著。处于不同经济发展阶段的区域,城市扩张所产生稀缺效应以及资本效应不断变化,因此政策上更应该关注如何发挥其正向效应,消减其负向效应。第二,在寻找调节城市扩张影响耕地利用强度的中间变量时发现:(1)当工业总产值大于509. 73亿元时,城市扩张对耕地利用强度的偏效应为负,即城市扩张导致耕地利用强度下降;反之,城市扩张将会促使耕地利用强度上升。(2)当地均机械投入大于816. 39 kW/km2时,城市扩张会促进耕地利用强度提高;相反,城市扩张将会阻碍耕地利用强度提高。(3)当户均耕地面积小于3. 36亩或大于13. 26亩时,城市扩张对耕地利用强度产生正向影响;当户均耕地面积介于3. 36～13. 26亩时,城市扩张对耕地利用强度产生负向影响。因此,为了引导城市扩张对农业投入的正向促进作用,需要协调城市扩张与产业发展,同时提升区域农业机械化水平,依托农地流转实现农地适度规模经营,并应当尽快完成工业化快速发展区域基本农田和城市发展边界划定工作。

The impact of urban expansion on the arable land use intensity is critical to the food security of China.Based on the county-level panel data of Jiangsu Province,this paper analyzed the mechanism of urban expansion’s influence on the arable land use intensity.Combining with the external environment conditions and internal endowments,this paper constructed a two-way fixed effects model to estimate the impact of urban expansion on arable land use intensity and study on the adjustment effect of regional industrialization level and farmers’resource endowment by adding interaction items.The results showed that the effect of urban expansion on the agricultural land use intensity was not statistically significant.It attributed to the offset between scarcity effect and the capital effect,which led to the insignificance of comprehensive effect.Considering the regions at different stages of economic development,the scarcity effect and capital effect caused by urban expansion were constantly changing.Thus,when making policies,we should pay more attention to how to play positive role of urban expansion and to weaken its negative effects in order to ensure food security effectively.When investigating the regulating effect of the mediating variables of urban expansion on the arable land use intensity,it is found that:①When the gross value of industrial output was greater than 50.973 billion CNY,the bias effect of urban expansion on the arable land use intensity was negative;that is,urban expansion led to a decrease in the intensity of arable land use.On the contrary,urban expansion would increase the arable land use intensity.②When the total agricultural machinery power was greater than 816.39 kW/km 2,urban expansion would promote the increase of arable land use intensity;on the contrary,urban expansion would hinder the increase of arable land use intensity.③When the average cultivated land per household was less than 3.36 mu or more than 13.26 mu,urban expansion would have a positive impact on the arable land use intensity.On the contrary,when the average cultivated land per household was between 3.36 and 6.16 mu,urban expansion would negatively affect the arable land use intensity.In order to guide the positive role of urban expansion in agricultural investment,it is necessary to coordinate urban expansion and industrial development,improve the level of regional agricultural mechanization,rely on the circulation of agricultural land to achieve a moderate scale of agricultural land management,and at the same time complete basic farmland and urban development boundary demarcation work in the rapid industrial development region as soon as possible.