Spatial-temporal Coupling Of Cultivated Land Use Pattern And Agrochemical Inputs In China And Analysis Of Environmental Effects

Due to the unbalanced development of regional economy and the strict dynamic balance target of total cultivated land set by the government,cultivated land tends to move from developed to undeveloped regions.The undeveloped regions of China are mainly located in the west,where the endowment of cultivated land is worse and more agrochemical inputs are needed for grain production per unit area,and the ecology is extremely fragile,so the environmental risks from the westward shift of cultivated land use pattern may be far more serious than it appears.How to deal with the relationship between the transfer of cultivated land use pattern and agrochemical inputs is a problem that agricultural development faces and needs to be solved urgently.Based on the theories of ecological economy and economic geography,this study used the panel data of grain sown area and agrochemical inputs(including fertilizer,pesticide,mulch film,and agricultural diesel)used for grain production at the provincial level from 2000 to 2020 to establish the relevant measurement models,and studied the regional variation characteristics of cultivated land use and the corresponding change process of agrochemical inputs,to reveal the coupling and coordination relationship between cultivated land use pattern and agrochemical inputs in China,and measure the environmental effects brought by the transfer of cultivated land use pattern.Firstly,the gravity center model and standard deviation ellipse model were used to calculate and analyze the spatio-temporal variation patterns of cultivated land use and agrochemical inputs in China.Secondly,the spatial autocorrelation analysis of Geo Da is carried out to illustrate the spatial agglomeration characteristics of cultivated land use pattern and agrochemical inputs.The coupling coordination degree model was used to estimate the coupling coordination degree of the two in China,and Arc GIS platform was used to demonstrate the coupling coordination relationship between the two.Then,with the help of elastic coefficient and contribution rate analysis methods,the influences of cultivated land use pattern on agrochemical inputs at provincial scale were identified,and the situation of agrochemical inputs in each province was analyzed under different characteristics of cultivated land use change.At the same time,a spatio-temporal double-difference model was established to estimate and analyze the environmental effects of the transfer of cultivated land use pattern in China.Finally,the relevant conclusions of this paper were summarized,and further suggestions were put forward to protect the agricultural ecological environment in western China under the condition of guaranteeing the dynamic balance of total cultivated land.The results showed that:(1)Without the Northeast China,the gravity centers of grain sown area and various agrochemical inputs migrated to the west in China from 2000 to 2020,and the gravity center of agrochemical inputs shifted to the west faster than the grain sown area,which was as follows: mulch film(12.80 km/a)> fertilizer(7.66 km/a)> pesticide(5.62 km/a)> agricultural diesel(5.03 km/a)> grain sown area(4.64 km/a).(2)The Moran’s I of grain sown area and agrochemical inputs were both positive at all time nodes,indicating that the provinces with high or low grain sown area and agrochemical inputs tended to agglomeration,and the spatial agglomeration types of the two regions overlapped.At the same time,the coordination degree between grain sown area and agrochemical inputs was improved in the whole country and the central and western regions.In particular,the coupling coordination level between grain sown area and agrochemical inputs was still at moderate coordination level or above.(3)The influence elasticity analysis of grain sown area on agrochemical inputs in China can be divided into four types: "positive-positive change zone","negative-negative change zone","positive-negative change zone" and "negative-positive change zone".At present,the "positive-positive change zone" and "positive-negative change zone" include all the western provinces except Qinghai,which are characterized by increased agrochemical inputs.The spatio-temporal double-difference model was used to measure the environmental effects of the change in cultivated land use pattern.The results showed that the westward shift of cultivated land use pattern increased the agrochemical inputs per land in western China,which gave the reason why the westward shift of agrochemical inputs was faster than the grain sown area.According to the above conclusions,this study puts forward countermeasures and suggestions for the environmental effects of the westward shift of cultivated land use pattern to the west.Under the current goal of maintaining the dynamic balance of total cultivated land,firstly,the ecological compensation mechanism should be established to ensure farmers’ income affected by pollution from non-point agricultural sources.Secondly,we should adjust the grain planting structure reasonably and reduce the grain crops sown area with high agrochemical inputs level.Finally,it is necessary to establish a safe upper limit for agrochemical inputs in the western region to reduce the risk of pollution from non-point agricultural sources at the source.