Study On The Main Influence Factors Of Fallow And Their Impacts On Food Security In China

The economic developing pattern of emphasizing speed and ignoring equilibrium of nearly three decades in China leads to ecological environment worsening.As a result,a large number of high-quality farmland resources are occupied by urban land or industrial and mining land.The unreasonable exploitation and utilization of cultivated land has aggravated the pollution of soil and water resources,seriously threatened the environmental security and public health,and affected the overall sustainability of social and economic development.In 2014,the National Soil Pollution Survey Announcement published by the state showed that 19.4% of the soil point data exceeded the national soil environmental quality standard,and 10.3% of the rice in 9 major rice producing areas exceeded the cadmium standard in China,indicating that it is urgent to face up to the food safety problem.In order to practice the concept of "green mountains and clear waters are mountains of gold and silver" and solve the problem of farmland pollution,the state advocates the implementation of fallow strategy.Previous scholars have carried out extensive research on the connotation of fallow and its natural-economic-social benefits,farmers’ willingness of fallow and compensation standards,etc.But there is no clear answer to these three most fundamental questions: "where is the fallow? ","how much fallow? " and " how to fallow? " Fallow not only involves social and economic problems such as population growth,dietary structure and economic development,but natural conditions such as cultivated land quality,ecological vulnerability and soil pollution.In addition,the impact of fallow on food security also needs to be further studied.Based on the main control factors affecting fallow,such as soil pollution status,cultivated land quality grade,spatial distribution of overdrawn groundwater area and ecological protection red line,this thesis divided fallow areas according to the differences of main control factors of fallow in different agricultural areas in China by using spatial statistics and analysis methods.Then,requantifing the potential impact of different fallow scenarios(based on food safety first,arable land quality first and ecological protection first)on food security.Finally,under the constraints of food security,the optimal fallow plan in China based on food security priority was explored,which comprehensively considers the quantity security,quality security and ecological security of cultivated land.In this thesis,by identifying the main cinfluence factors of fallow and their impacts on food security to serve for the realization of "storing grain on land",sustainable transformation of agricultural development and national food security.It also can provide a basis for fallow planning at national level and balance the contradictions between the construction of ecological civilization and cultivated land use in the new era.The main conclusions are as follows:(1)The four main controlling factors affecting fallow in China are distributed in different grades in space.The proportion of the combined pollution of cultivated land in China is 22.10%,and the proportion of light pollution,moderate pollution and severe pollution are 18.56%,2.31% and 1.23%,respectively.The quality of cultivated land is generally not high,with medium land being the main part.The underground over-mining areas are mainly concentrated in north and northeast China,with mild,moderate and severe areas of 3.66%,3.83% and 0.68%,respectively.There are 1.616 million hectares of arable land within the scope of the Ecological Protection Red Line,accounting for 14.52 percent of the total arable land in China,of which 3.57 percent is within the first-level.(2)The concept models of different scenarios evaluated the priority combination of fallow in China.The fallow areas of low,medium and high grade fallow target combinations based on food safety priority account for 4.94%,9.64% and 15.30% of the total cultivated land area,respectively.The fallow areas of low,medium and high grade fallow target combinations based on the priority of cultivated land quality account for 6.65%,9.83% and 19.52% of the total cultivated land area,respectively.The fallow areas of the combination of low,medium and three categories of fallow targets based on ecological protection priority account for 5.70%,10.01% and 20.58% of the total cultivated land area,respectively.(3)Taking no account of national food security and financial pressure,the total fallow area is 443.46 million hectares China,accounting for 32.87 percent of the total arable land.According to the differences in the main control factors of fallow in different regions,the fallow categories such as clean and deconflict type,soil productivity improvement type,water-saving type and ecological protection type were developed,and differentiated fallow treatment measures were suggested for cultivated land resources in different grades and regions.(4)Different combinations of fallow goals have significant differences in grain productivity loss.Based on the ecological security priority scenario,the combination of high fallow goals resulted in the reduction of grain yield in China from 17165.35 to 253.8662 million tons,which was much higher than the impact of food security priority combination and arable land quality priority combination on grain productivity.To ensure the high self-sufficiency in grain,the maximum fallow area is 18.18 million hectares.Under the natural-social-economic system,the low-grade,medium-grade and third-grade fallow schemes considering food security were formulated,with fallow area of 9.93,17.32 and 29.64 million hectares,respectively.To protect farmers’ livelihood,ensure fallow subsidies in state and local governments within the acceptable range,and without causing big negative impact on the national food safety,we suggest to formulate the low,medium and high fallow scheme according to the proportion of 1.7:5.1:3.2,3.9,2.4,3.7 and 2.3:3.6:4.5 to determine the scale of fallow in the recent(2021-2025),medium(2026-2030)and forward(2031-2035)period,respectively.The implementation of fallow in different regions of China should be carried out in accordance with local conditions,and the fallow programs should be scientifically classified and implemented in different periods,so as to realize the agricultural transformation,improve grain production capacity and guarantee national food security.There are 40 charts,25 tables and 231 references in this thesis.