| With the development of social economy and the acceleration of urbanization,China’s cultivated land is facing many practical problems such as serious abandonment,widespread"domestic and inferior",agricultural product safety and soil environmental pollution.Cultivated land has always been the basis of agricultural production.The quality of cultivated land is a direct factor related to agricultural production capacity.Carrying out the evaluation of cultivated land quality grade is an effective way to find out the quality of cultivated land,ensure national food security,and realize the protection and utilization of cultivated land resources.It is also an important component of the third national land use survey.It is of great significance to ensure the improvement of cultivated land quality,improve the farmland protection policy,promote the sustainable use of cultivated land resources,and promote the green development of agriculture and the structural reform of supply side.This study takes ChaoHu City as the research area,and carries out the evaluation of cultivated land quality grade and time-space change.On the basis of collecting sample data and various thematic data,the ARCGIS,cultivated land resource management information system and other software and spatial analysis techniques are used to divide the cultivated land quality grade evaluation unit,determine the cultivated land quality grade evaluation index system,and use the AHP(AHP).And Delphi method(DELPHI)weights and construct a membership function model,determine the cleanliness of cultivated land by calculating the soil comprehensive pollution index,and finally divide the cultivated land quality of ChaoHu City into ten grades,and divide the results with the quality grade of cultivated land ten years ago.The horizontal comparison was carried out to analyze the spatial and temporal changes of the quantity,quality and soil nutrient of cultivated land in ChaoHu City since 2008-2017,and to propose targeted countermeasures for the problems in the change.Research indicates:(1)At the end of 2017,ChaoHu City had a total of 77,892.24 hectares of cultivated land,and the quality of cultivated land was generally at a medium level.The high-grade cultivated land(first,second and third grade)has a total of 14,463.18 hectares,accounting for 18.57%.Among them,the first-grade land is 1,078.37 hectares,the smallest area,accounting for 1.38%,concentrated in XiaGe Town;the second-grade land is 5,862.74 hectares.The proportion is 7.53%,mainly located in MiaoGang Town;the third-grade land is 7,522.07 hectares,accounting for 9.66%,and MiaoGang Town is mostly;the medium-grade cultivated land(fourth,fifth,sixth grade)has the highest proportion,totaling 41,188.23 hectares,accounting for 52.88%.Among them,13,098.17 hectares in the fourth-grade area,accounting for 16.82%,HuangLu Town is the most distributed;the fifth-grade land is 13,239.22 hectares,accounting for 17.00%,mostly distributed in the LanGanji Town;the sixth-grade land is the largest,accounting for 1,450.84 hectares,accounting for 19.07%.XiaGe Town has the most distribution;low-grade cultivated land(seventh,eighth,ninth,tenth grade)has a total area of 2,846.29 thousand hectares,accounting for 28.55%,of which the seventh-grade land has the largest area,with 9,788.02 hectares,accounting for 12.81%,mostly distributed in HuaiLin Town;8,547.66 hectares in the eighth-grade land,accounting for 9.69%,SuWan Town is the most distributed;4,060.66 hectares in the ninth-grade land,accounting for 5.21%,Suwan Town is the largest;654.49 hectares in the tenth-grade land,only 0.84%,mainly located LanGanji Town.(2)In the past ten years,the number of cultivated land in ChaoHu City has generally increased.Compared with 2008,the area of cultivated land in ChaoHu City increased by 30,091.86 hectares in 2017.Among them,the high-grade cultivated land area in ChaoHu City increased by 8,361.32 hectares,an increase of 5.80%,among which the high-grade cultivated land area in MiaoGang Town increased the most,and the number of high-grade cultivated land in ZhongHan Town decreased the most;the medium-grade cultivated land area increased by 14,807.57 hectares.The proportion decreased by 2.31%,among which the area of graded cultivated land in LanGanji Town increased the most,and the number of graded cultivated land in SuWan Town decreased the most;the area of low grade arable land increased by 6,992.97 hectares,accounting for 3.49%of the total,the area of low-grade arable land in SuWan Town and ZheGao Town increased the most,and the number of low-grade arable land in MiaoGang Town decreased the most.(3)In the past ten years,the quality of cultivated land in ChaoHu City has generally improved.In the area where the quality of cultivated land in ChaoHu City changes,there are three types of cultivated land quality grades,grades and grades.Among them,ChaoHu City has the largest area of cultivated land quality improvement,with a total area of 31,763.32 hectares,accounting for 40.78%of the total cultivated land area,mainly concentrated in MiaoGang Town and HuaiLin Town,with the lowest in ZhongMiao Street;the area of cultivated land quality grade in ChaoHu City remains unchanged.There are 18,099.12 hectares,accounting for 23.24%of the total cultivated land area,of which the number of railing towns and towns is the largest,and the number of FengHuangshan Street is the least;the area of cultivated land quality in ChaoHu City is 28,029.8 hectares,accounting for 35.98%of the total cultivated land,mostly located in the area.TongYang Town and SuWan Town,TianHe Street is the least.At the same time,targeted improvement and protection measures are proposed for different types of cultivated land.(4)In the past decade,the soil nutrient level of cultivated land in ChaoHu City has increased steadily.The organic matter content of cultivated land gradually increased,the proportion of cultivated land with high organic matter increased by 4.03%,and the proportion of low-level cultivated land decreased by 20.19%;the level of available phosphorus in cultivated soil was stable overall,and the proportion of low-level cultivated land decreased by 12.72%;cultivated soil The level of available potassium increased gradually,the proportion of cultivated land with high level of available potassium increased by 2.49%,and the proportion of low-level cultivated land decreased by 23.33%. |
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