Study On Arable Land Security Assessment At County Scale

Arable land is the most important foundation for human survival and development.The reduction and degradation of arable land will result in the loss of ecosystem services,and ensuring the arable land security is the key to coordinating the relationship between human and land.Also,it can promote our country's food security and sustainable development.At present,there is no consensus on the cognition of arable land security,the assessment index lacks the consideration of arable land itself,and the research scale is generally macro,these studies are applicable to policy making and planning regulation,but they are insufficient to guide agricultural production practice.This thesis mainly studied the connotation,mechanism,assessment index system,application of assessment results,and management measures of arable land security,and conducted an empirical study on arable land security at county scale in Yixing County and Wen County,so as to improve the theory of arable land security assessment and promote the effective protection of arable land.The main research contents and conclusions are as follows:Based on the analysis of the components and interrelations of soil and arable land,the connotation of arable land security is extended from the international definition of soil security,and it is considered that arable land security is the maintenance and improvement of regional arable land resources to ensure that it can continuously and steadily perform various functions and meet the needs of human survival,health and sustainable development.The structure of arable land security system consists of the arable land subsystem and the social economic subsystem.Based on the soil ecosystem service,the relationship of "Demand-Security-Service-Function" is established.According to the thought of causal analysis of system dynamics,the thesis analyzed the operation mechanism of arable land security system,which is the interaction between man,natural environment and arable land.This thesis established a arable land security assessment index system based on “5C” dimension(capability,condition,capital,connectivity and codification),and analytic hierarchy process,weighted summation method and generalized mean algorithm are used to evaluate the single dimension and comprehensive assessment of the research area.The comprehensive index of arable land security in Yixing County is between 59.23 and 90.57,and the comprehensive index of arable land security in Wen County ranges from 60.76 to 95.01.The arable land area of different security levels in Yixing County and Wen County is in the same order,with the most arable land area of "moderate to high security" and the least arable land area of "unsafe".The "unsafe" farmland in Yixing County is mainly distributed in the southern towns of Taihua and Dingshu,Wen County's "unsafe" arable land is concentrated south of Wenquan town.Poor soil type,low content of nutrients and organic matter,low content of microbial carbon,soil respiration or earthworms,and imperfect management measures are common problems in unsafe arable land.In addition,"unsafe" arable land in Yixing County is also affected by soil erosion and pollution.The average security index of arable land in Yixing is 83.70,and the average security index of arable land in Wen County is 87.55,also analyzed the impact of economic development level and urbanization level on arable land security.According to the change of land use status,the dynamic degree of arable land change and the transfer of arable land center in Yixing County and Wen County,it is predicted that the overall security level of arable land in Yixing County is declining slowly and that of arable land in Wen county is rising steadily.The stability of arable land is determined by land type transfer matrix and map.In view of the problems existing in the delimitation of basic farmland,this thesis combines the security assessment of arable land with the stability of arable land in the dimension of "4C" to delimit the "priority delimitation area","suitable delimitation area" and "unsuitable delimitation area" of basic farmland,and designed a plan for basic farmland adjustment,and the adjusted arable land security has improved.According to the regional characteristics of Yixing County and Wen County,it is suggested that the management and protection of arable land security should be carried out from the aspects of coordinating the relationship between urban development and arable land security,land renovation and high standard farmland construction,ecological restoration and prevention mechanism,legal system improvement,dynamic monitoring of arable land security.