| Ensuring food security is conducive to China’s economic development,social stability and political security,and is an important cornerstone of safeguarding national security.Under the influence of economic development and population growth,China’s grain output is increasing steadily,while the amount of chemical fertilizer is also increasing exponentially,which accelerates the deterioration of the ecological environment.In the context of resource and environment constraints and high-quality agricultural development,a mode of agricultural production designed to increase output by relying on inputs of large quantities of factors of production.Instead,the conflict between food production and environmental protection is deepening.How to balance the relationship between food production and environmental protection has always been a hot issue in academic circles.Due to the natural nature of agricultural planting,agricultural planting pattern is closely related to chemical consumption.Different planting structure of food crops will produce different fertilizer demand and fertilizer application intensity,which will lead to different fertilizer non-point source pollution emissions.Then,what is the impact of different crop planting structures on fertilizer non-point source pollution? What is the path? In ensuring food security and stability of grain production,on the basis of exploring the grain crop planting structure adjustment within the influence of the non-point source pollution of fertilizers,promote non-point source fertilizer pollution internalization of negative externalities,so as to promote food security and to reach a balance between ecological environment protection,to achieve “jinshan silver”and“green water castle peak” win-win situation.As the Yangtze River Economic Belt is an important region to ensure the safety of food production and promote the healthy development of agriculture in China,this paper takes the Yangtze River Economic Belt as a representative research object.Based on the environmental Kuznets curve theory,public goods theory and externality theory,this paper studies the impact of food crop planting structure on non-point source fertilizer pollution by using the municipal data of 103 cities in the Yangtze River Economic Belt from 2000 to 2019.Firstly,the viewpoints and classical theories of scholars at home and abroad were summarized to analyze the internal logic and influence path of planting structure of food crops and non-point source fertilizer pollution.Secondly,measure non-point source fertilizer pollution and explain the time and space evolution trend of non-point source fertilizer pollution.Thirdly,the spatial Dubin model was used to explore whether the spatial spillover effect of crop planting structure on non-point source fertilizer pollution.The robustness of the model was tested by replacing the spatial matrix,and the regional heterogeneity was analyzed.Finally,the threshold effect of crop planting structure on non-point source fertilizer pollution was discussed with farmers’ disposable income as the threshold variable,and the robustness test and regional heterogeneity analysis were carried out.The results showed that :(1)the emissions of non-point source fertilizer pollution in the Yangtze river economic belt showed an inverted u-shaped growth trend in time and the spatial distribution is not uniform and has a diffusion trend;It shows strong spatial positive correlation in space.(2)The planting structure of wheat and maize showed significant spatial dependence on non-point source fertilizer pollution.The planting structure of grain crops had a significant positive spatial dependence on local non-point source fertilizer pollution,and inhibited the emission intensity of non-point source fertilizer pollution in adjacent areas.(3)Crop planting structure of grain,rice,wheat and corn planting proportion showed significant double threshold effect,in addition to the proportion of corn,and other core explanation variable of non-point source fertilizers pollution shows the characteristics of nonlinear,among them,the structure of grain crop,wheat planting proportion of non-point source fertilizer pollution present a “suppress-promote suppression”,The proportion of rice planting had a “suppression-promotion” effect on non-point source fertilizer pollution.Based on the research results,several suggestions were put forward :(1)while maintaining the balance of total grain planting,the cropping structure of grain crops should be adjusted appropriately in the Yangtze river economic belt to achieve both stable yield and emission reduction.(2)We should pay more attention to the grain production in the Grain production and marketing balance areas,and appropriately adopt compulsory external intervention measures to curb the pollution emissions from non-point sources fertilizer pollution.(3)Considering the spatial spillover effect of non-point source fertilizer pollution,the Yangtze River Economic Belt region should establish a cooperative agricultural pollution control community,form a linkage mechanism of non-point source fertilizer pollution control,strengthen inter-city agricultural exchanges and cooperation,and comprehensively control non-point source fertilizer pollution. |
