Spatial And Temporal Variations Of Fertilizer Usage Across Prefecture-Level Cities In China From 2000 To 2015

Excessive use of chemical fertilizers will bring about a series of environmental problems,such as eutrophication of surface water,deterioration of soil structure and decline of agricultural carrying capacity.At present,the research on chemical fertilizer is mostly focused on the utilization efficiency,but the research on the characteristics of spatial change is very few.It is of great significance to fully understand the spatial change of chemical fertilizer use for the healthy and sustainable development of agriculture in China.In this paper,four time sections in 2000,2005,2010 and 2015 were selected from 2000 to 2015,and the spatial changes of chemical fertilizer use in China were studied by means of spatial autocorrelation,cold and hot spot analysis,nuclear density analysis,center of gravity model and so on.The reasons affecting the use of chemical fertilizer were analyzed.The results show:(1)The total amount of chemical fertilizer use in China showed a linear increasing trend from 2000 to 2015,and the spatial correlation was significantly positive and the distribution was extremely uneven.The high value area of chemical fertilizer use is mainly distributed in the eastern and central regions of China,especially in Northeast China.In the past 16 years,the amount of chemical fertilizer in the eastern coastal areas has slowed down,while the western and northeast regions have shown an increasing trend.(2)From 2000 to 2015,the number of prefecture-level cities with excessive use of chemical fertilizer increased and the area became wider.Areas with relatively rapid economic development in the eastern region,such as Guangdong Province and Fujian Province,have more dense cities at the prefecture level that exceed the standard because the reduction in sown area is greater than the increase in chemical fertilizer use.The gathering area of over-standard prefecture-level city is not consistent with the high value area of chemical fertilizer consumption.(3)The moving track of the center of gravity of grain in China from 2000 to 2015 is not consistent with that of chemical fertilizer use,and they move in a vertical direction.,which also shows that the change of planting structure in China will affect the movement and distribution of chemical fertilizer use.There are many reasons for the uneven spatial distribution of chemical fertilizer use.Natural factors such as topography,climate and rainfall will directly determine whether an area is suitable for agricultural production activities,so geographical factors directly lead to the uneven spatial distribution of chemical fertilizer use.Among the human factors,the sown area and effective irrigation area have the greatest influence on the use of chemical fertilizer,and the increase of the proportion of economic crops in agricultural production has also promoted the increase of chemical fertilizer use to a certain extent.The strategy put forward by the state to revitalize the large-scale development of the northeast and western regions has also stimulated the development of agriculture to a certain extent,leading to an increase in the use of chemical fertilizers.All regions should take measures to suit local conditions and formulate different measures for reducing chemical fertilizers.The reduction task of chemical fertilizer should focus on the eastern and central regions,while the western region should give priority to prevention and control the further spread of high value areas of chemical fertilizer use.It is necessary to control the further diffusion of high value areas of chemical fertilizer use.The use of chemical fertilizer in the economically developed areas of the eastern coastal areas is more than the prefecture-level cities,especially in Fujian Province and Guangdong Province,so we should strive to slow down the excessive use of chemical fertilizer in these two economically developed provinces.For farmers,the most important thing is to guide scientifically and teach reasonable fertilization methods.It is fundamental to appropriately adjust the country's agricultural policy and promote the technological innovation of environmentally friendly chemical fertilizers.