Identification And Spatio-Temporal Collocation Of Cultivated Land Fallow Based On Efficiency And Ecology

In recent years,with the continuous advancement of new industrialization and urbanization,the contradiction between the reduction of cultivated land and the growth of food demand has become increasingly fierce.The intensive,chemical,and large-scale agricultural production has made the cultivated land face multiple challenges such as re-use and light-weight,quality degradation,and ecological and environmental pollution,which has seriously hindered the sustainable use of cultivated land and the development of agricultural modernization.In this context,“the pilot of the implementation of the cultivated land rotation system for fallows” is proposed in the “Proposal of the Central Committee of the Communist Party of China on Formulating the Thirteenth Five-Year Plan for National Economic and Social Development” Carrying out the trial of cultivated land rotation and fallow system is an important measure to accelerate the construction of ecological civilization and realize the sustainable development of agriculture.With the development and promotion of the pilot system of cultivated land rotation,the in-depth study on the rotation of cultivated land is particularly urgent and important.The research on the identification of cultivated land fallow and the allocation of time and space can provide reference for the scientific identification of fallow area,reasonable determination of fallow scale,and realization of time and space allocation of fallow.It has important theoretical and practical significance for the trial of cultivated land rotation fallow system.This paper takes the Liangshan Yi Autonomous Prefecture of Sichuan Province as study area,which is an important ecological barrier,the typical ecological and environmental fragile zone in the upper reaches of the Yangtze River.Four-stage DEA model and grey relational projection method is used to analyze the dynamic change ofcultivated land use efficiency and cultivated land ecological security value of counties(cities)in Liangshan Prefecture from 2012 to 2016.The cultivated land fallow area is identified and determined based on the perspective of efficiency and ecology.Besides,on the basis of comprehensive consideration of food security and economic development,the demand for cultivated land and the supply of cultivated land will be predicted.After conducting a balance analysis,the scale of fallowable farms in different fallow areas will be determined.In the end,based on the cultivated land productivity,the terrain index and other indicators are selected for correction,and the comprehensive quality evaluation value of cultivated land is obtained.The allowable scale of each fallow area is used as the constraint,and the spatial allocation of fallow land is carried out.And the relevant measures for the implementation of fallow work will be proposed.The main findings are as follows:(1)The utilization efficiency of cultivated land in Liangshan Prefecture is higher overall,but some counties have fluctuating downward trend;the ecological status of cultivated land is generally fragile,and the safety status of cultivated land in some counties is declining dynamically.Based on efficiency and ecological perspective,4counties such as Yanyuan are diagnosed as fallow land for cultivated land.During the study period,the comprehensive utilization efficiency of cultivated land in 17 counties(cities)of Liangshan Prefecture was higher overall,and the proportion of county(city)with the best comprehensive utilization efficiency of cultivated land in different periods exceeded 50%;the comprehensive efficiency of cultivated land changed more obviously.There are three types including stable development type,fluctuating rising type and fluctuating falling type.Cultivated land ecological security is generally fragile,and the safety status of cultivated land in most counties(cities)is “unsafe” and “less safe”.The ecological security changes of cultivated land mainly show four types: maintaining safer type,maintaining general safety type,general safety to safer,less secure-unsafe transformation.Based on the spatial superposition analysis of utilization efficiency and ecological security,the quality of cultivated land in Yanyuan,Ganluo,Jinyang and Yuexi counties decreased and the ecological degradation,and the four counties such as salt source were identified as cultivated land fallow areas.(2)On the basis of ensuring food security and economic development,the demand and supply of cultivated land and conduct a balanced analysis is predicted as follows.Calculating the total fallow size of Phase I(2016-2020)is 9880.39hm2,Phase II(2021-2025)the total fallow size is 2268.19hm2.In the two stages,there are significantdifferences in the size of fallow farms in the four fallow counties.In the first phase(2016-2020),the fallow scales of Yanyuan,Jinyang,Yuexi and Ganluo counties were950.77hm2,2892.45hm2,4979.97hm2 and 1057.20hm2 respectively;In the second phase(2021-2025),the number of fallow farms in Jinyang and Yuexi counties are 1251.37hm2 and 1016.82hm2 respectively.In Yanyuan County and Ganluo County,the amount of cultivated land exceeds the supply of cultivated land,and the scale of fallowing can be zero.(3)Based on the evaluation of the scale of fallow and the comprehensive quality of cultivated land,the space allocation of the fallow land in Phase I and Phase II of the fallow area is carried out.The suggestions on the implementation and policy support of farmland fallow work are put forward.The first-stage fallow land is mainly distributed in the northeastern part of Yanyuan County,the mountainous area in the northwestern margin,and the Bajiao Township in the southwest.The central part of Jinyang County and the northwest corner of Yida Township,Jiayi Township and Bingdi Township,etc.And the northwest of Yuexi County and the southern town of Ersai Township,Wusi Bridge Township in the north of Ganluo County,etc.The phase II fallow land is concentrated in 7 townships in the central and western parts of Jinyang County and in the northwest and south of Erjue Xixiang,Gaofeng Township,Xiaoyinmu Township and Yuexi County.