Exploring The Fallow Zoning Based On Double Constraints Of Ecological Security And Food Security

Fallow is an effective measure to protect and restore the ecological environment,maintain and enhance the productivity of cultivated land,and adjust agricultural planting structure.Under the pressure of the world's largest population and food security,the utilization of cultivated land resources in China is too intensive for a long time.Both sustainable utilization of cultivated land and development of agriculture are seriously restricted by the serious decline of cultivated land fertility,groundwater overexploitation,soil erosion and soil pollution in some areas.Although the farming system which combining land use and land nourishment in Chinese has a long history,however,the construction of modern fallow system in China is relatively late,and many problems of fallow need to be further studied.Under the forces which include of the overdraft of some agricultural resources and environment,the structural reform of the agricultural supply side,the construction of ecological civilization in China,the Fifth Plenary Session of the 18th Central Committee of the Communist Party of China for the first time put forward a major decision-making to"explore the pilot of cultivated land rotation and fallow system".General Secretary Xi Jinping pointed out in the Note on the Proposals of the Central Committee of the Communist Party of China on the Thirteenth Five-Year Plan for National Economic and Social Development that"the implementation of rotation and fallow in some areas is not only beneficial to the recuperation of cultivated land and the sustainable development of agriculture,but also beneficial to balancing the contradiction between food supply and demand,stabilizing farmers'income and alleviating financial pressure".He also pointed out that the rotation and fallow must to ensure national food security and not affect farmers'income.In June 2016,the Ministry of Agriculture and other ten ministries jointly issued the Pilot Plan for Exploring and Implementing the Rotation and Fallow System.In that year,7.73×10~4 hm~2 farmland was fallowed nationwide.Yanshan County in Yunnan Province is one of the first pilot counties of fallow system in China,with a pilot area of 666.67 hm~2in 2016,and increased to 1333.33 hm~2 in 2017,what's more,Yunnan Province increased to 13333.33 hm~2.With the promotion of fallow in rocky desertification region,a series of theoretical and practical problems such as which land should be choose for fallow,how to predict fallow scale,and so on,have become more and more prominent.The rocky desertification area is an important ecological barrier and a typical ecologically fragile area in China.However,the existing measures for controlling rocky desertification have not reduced the intensity of cultivated land utilization.Therefore,the traditional ways of cultivated land use in rocky desertification areas have not been able to realize the transformation fundamentally.Fallow is an important means to realize the strategy of"storing grain on the ground",and it is also a balance point to maintain ecological security and food security in rocky desertification areas of Southwest China.Under the working mechanism of"central overall planning,provincial responsibility and county implementation"in the fallow pilot,the county is the main body of organizing and implementing of fallow.However,due to the insufficiency of county-level research,there are many obstacles to the implementation of fallow mechanism at the county level.In rocky desertification areas,problems such as unscientific selection of fallow land and uncertainty of fallow scale have been exposed.Besides,fallow must to ensure national food security and not affecting farmers'income.Therefore,fallow in rocky desertification areas should not only give priority to ecology,protect and restore the ecological environment of cultivated land,but also take food security as the premise.In this paper,Yanshan County,a pilot county of national fallow system,was taken as the research area,and the ecological orientation was used to measure the urgency of fallow in cultivated land which below 25°,so as to clarify the urgency of fallow for each cultivated land.And then,a prediction model was established to predict the fallow scale of the study area in 2020under the restriction of food security.Finally,the urgency of fallow based on ecological security and the scale of fallow based on food security were unified,and fallow zoning was carried out at the township and village levels,so as to realize the zoning optimization of the fallow area in Yanshan County,and provide a reference for decision-making of fallow planning too.The main research contents and conclusions of this paper include:Firstly,with the perspective of ecological security,based on Vulnerability Scoping Diagram(VSD)model and Pressure-State-Response(PSR)model,combined with the actual situation of Yanshan County,comprehensive evaluation model of cultivated land fallow urgency in Yanshan County was established from four aspects which are exposure(E),sensitivity(s),cultivated land pressure(P)and fallow response(R).Depend on ArcGIS platform,36806 cultivated land spots below 25°in Yanshan County were calculated for the urgency of fallow,and according to the calculation results,they were divided into 5 grades according to the Natural Breaks(Jenks)method.The results showed that the comprehensive score of 0.1966-0.2905 was Non-urgent,covering9188.77 hm~2,accounting for 6.96%of the total cultivated land.The comprehensive score of0.2905-0.3375,which is the general urgent level,covering an area of 28725.13 hm~2,accounting for21.76%of the total cultivated land.The comprehensive score of 0.3375-0.3830 is relatively urgent,covering an area of 48786.89 hm~2,accounting for 36.95%of the total cultivated land.The comprehensive score is 0.3830-0.4333,which is very urgent,covering an area of 36456.37 hm~2,accounting for 27.61%of the total cultivated land.The comprehensive score of 0.4333-0.6214 is extremely urgent,covering an area of 8862.34 hm~2,accounting for 6.71%of the total cultivated land.Therefore,the urgency of fallow in Yanshan County is mainly at the level of relatively urgent and above,levels of relatively urgent,very urgent and extremely urgent reach 94105.60 hm~2 in total,accounting for 71.28%of the cultivated land area in the county.In a word,it is necessary to implement fallow in Yanshan County.Secondly,taking regional food security as the constraint,considering the population,grain yield per unit area,multiple cropping index,grain sowing ratio,grain self-sufficiency rate and per capita grain demand as factors,the prediction model of fallow scale in the target year was constructed.According to the time series data,GM(1,1)grey prediction model and linear regression model were used to predict the factors above,the results were 514882,3988.20kg/hm~2,234.83%and 43.00%respectively.Combined with the existing research results,three grain self-sufficiency rate were set which are low self-sufficiency rate(80%),medium self-sufficiency rate(90%)and high self-sufficiency rate(100%),and three levels of low demand(500 kg/person),medium demand(550 kg/person)and high demand(600 kg/person)were set too,therefore,we can get the fallow scale of the target year under 9 scenarios.Among them,under the situation of low self-sufficiency rate and low per capita grain demand,the available fallow scale is 80878.57 hm~2,accounting for 61.26%of the total cultivated land of the county.While under the situation of high self-sufficiency rate and high per capita grain demand,the fallow scale was 55308.09 hm~2,accounting for 41.89%of the total cultivated land.In summary,the fallow scale of the study area is55308.09 hm~2-80878.57 hm~2,accounting for 41.89%-61.26%of the total cultivated land in the county.Therefore,the pilot of fallow will not have a big impact on the food security of Yanshan County.In addition to the current national pilot scale,Yanshan County can also arrange large-scale independent fallow.Thirdly,considering the situation of high grain self-sufficiency rate and high per capita grain demand,the urgency of fallow based on ecological security and the scale of fallow based on food security are coupled,and the towns and villages are taken as the unit to carry out the spatial division of fallow area,so as to realize the spatial optimization of fallow area.The concept of Comprehensive Farming Index(CFI)was put forward in this paper and the calculation model of CFI was established by three indexes.According to the CFI,the study area was divided into five types which are priority fallow region,key fallow region,conditional fallow region,reserve fallow region and non-fallow region.According to different types,different strategies of fallow were put forward.At the township level,priority fallow region is only Weimo,key fallow regions include 3towns,they are Pingyuan,Ameng and Ashe,conditional fallow regions include Baga,Benge and Jiayi,and reserve fallow regions include Zhela,Ganhe,Panlong and Jiangna.On the other hand,at the village level,priority fallow regions include 2 villages,key fallow regions include 12 villages,conditional fallow regions include 41 villages(communities),reserve fallow regions include 35villages(communities),and non-fallow regions include 8 villages(communities).By comparing the research results with the fallow pilot projects of Yanshan County in 2016 and 2017,it is found that they have a good corresponding relationship.Therefore,the research results can provide decision-making reference for the fallow planning of Yanshan County.Based on the above results,it can be seen that the evaluation of fallow urgency,the prediction of fallow scale and the spatial zoning of fallow are a logical and progressive technical system.The innovations of this paper are as follows.Firstly,based on the perspective of ecological security,this paper evaluates the urgency of fallow at the scale of land spots in rocky desertification area,develops the evaluation method of cultivated land ecological security,provides a feasible method for choosing which cultivated land to fallow and how to determine the fallow order of land in rocky desertification area,and effectively avoids the subjectivity of fallow land selection.Secondly,this paper constructs the prediction model of fallow scale in the study area under the restriction of food security.By setting different grain demand and self-sufficiency,we can get the upper and lower limits of fallow scale in the study area.Combined with the evaluation results of the urgency of fallow land,the fallow scale and the spatial distribution of fallow land in different towns and villages are obtained,which realizes the unity of"quantitative"and"positioning"of fallow land,provides ideas for further revising the spatial layout of fallow land,and provides scale basis and space basis for each town and village.Thirdly,according to the double constraints of ecological security and food security,the zoning rules of fallow are established by three index.The concept of comprehensive fallow index was put forward and divided the study area into different types of fallow regions both in township level and village level.This paper solves the problem that the spatial distribution of fallow land is separated from the fallow scale,combines the fallow land with the fallow scale effectively.To a certain extent,the zoning realizes the spatial optimization and provides a method for the fallow zoning.In a word,this study provides a feasible plan for the selection of fallow land(which land should be fallowed and it's order),the regulation of fallow scale(how much fallow land is)and the division of fallow region(how to fallow in different regions).This paper develops the spatial zoning method of fallow,enriches the theory of land use zoning,and also provides reference for the formulation and implementation of fallow planning in county.