Study On Spatiotemporal Variation Characteristics Of Cultivated Land Quality In Yueyang City

High-quality arable land is the key factor to ensuring food production safety and social stability.The Dongting Lake area plays an important role in food production in our country,in which,Yueyang City is an important part of the Dongting Lake District in Hunan Province.Mastering the distribution characteristics and evolution rules of cultivated land quality in Yueyang City is of great significance for guiding the conservation and improvement in the Dongting Lake District.The research object of this research article is the arable land in Yueyang City,according to "Cultivated Land Quality Grade"(GB/T 33469-2016),combined with Arc GIS software and the national cultivated land resource management information system to evaluate the quality of cultivated land in 2009 and 2019.Moreover,the temporal and spatial change characteristics of cultivated land quality are analyzed during the years.Following by an introduction of the obstacle degree function model to calculate the obstacle degree of each evaluation index of the unit,divide the area of the arable land quality obstacle type,and offer some effective suggestions for improving the quality.The key research findings are as following:(1)In 2009 and 2019,the average level of cultivated land quality in Yueyang City was 5.06 and 4.61,respectively.In the past 10 years,it has increased by 0.45 levels with an increased ratio of 8.89 % as a whole.The average level of quality in all counties,cities,and districts has improved.In Miluo City,it has improved the most,with an increase of 0.65 grades.In 10 years,the quality of the main cultivated land has transformed from low-medium to medium-high in Yueyang City.Among them,the third-tier arable land area increased the most significantly,while the fifth-tier arable land decreased the most.The area of upgraded cultivated land quality has reached 1.7 times the quality reduction in Yueyang City.Notably,the plowland area increased by one grade accounted for the largest proportion,and the change of cultivated land quality grade in most evaluation units fluctuated between-4～3(increased by 4 grades to decreased by 3 grades).(2)In 2009 and 2019,the distribution trend of Yueyang highlands was roughly the same,mainly in the southern part of Yueyanglou District,the central and southwestern part of Junshan District,the midland of Yunxi District,the central and western of Huarong County,the northern and northwestern area of Yueyang County,and Linxiang together with the north and south area of this city,the northwest of Miluo City and the southwest of Xiangyin County and Pingjiang County.In 2009,the low-level lands of Yueyang City were mainly spread over the southeast and northeast in Huarong County,the north and southwest of Junshan District,and the northwest of Miluo City.The low-level lands of other counties and cities were scattered.In 2019,they are mainly distributed in the southeast of Huarong County,southwest of Junshan District and other areas,and a small number of other counties and cities.In the past 10 years,the quality of cultivated land in the northeast of Junshan District,the north of Yueyang County,the east of Huarong County,the northwest of Xiangyin County,and the south of Pingjiang County have improved greatly.However,in the southwest of Junshan District,the northwest of Yueyang County,the southeast of Huarong County,the middle of Miluo City,and the southeast of Xiangyin County,the quality of cultivated land declined more.(3)According to the changes in the degree of obstacles in individual evaluation indicators during the past decade,the restrictive effect of irrigation and drainage capacity on the quality of cultivated land in Yueyang City has been significantly weakened;the restrictive effect of available phosphorus on cultivated land quality has been weakened;The restrictive effect of p H,organic matter and available potassium on the quality of cultivated land has increased to varying degrees.According to the changes in the area of cultivated land quality obstacle types in Yueyang City during the past decade,the areas with irrigation capacity and drainage capacity obstacles are finally determined as long-term key improvement areas.It is vital to vigorously improve the irrigation and drainage conditions of cultivated land,in the future.And the matter barrier areas of available phosphorus,available potassium,p H,and organic are short-term key improvement areas.In the future,efforts should be made to improve soil nutrient content and soil p H.