Research On The Method Of Grading Quality Of Cultivated Land Based On Two-Level Correction Method

Cultivated land is an important part of natural resources,and the investigation and evaluation of cultivated land quality is the basis for the protection and management of cultivated land.With the construction of high-standard basic farmland,the current agricultural land classification and grading system can not serve the country's needs for unified management of cultivated land.In order to realize the scientific and effective evaluation of the quality of cultivated land,this study proposes a two-level correction method for cultivated land based on the existing Agricultural Land Grading Regulations(GB/T28405-2012)combined with the results of domestic and foreign cultivated land quality researches.Taking Gushi County of Henan Province as an example,the rationality and feasibility of the two-level correction method is explored,in order to provide references for the scientific quantification of the quantity,quality and distribution of cultivated land,the realization of the balance of cultivated land occupation and the implementation of the basic farmland protection system.The specific research contents and results are as follows:(1)The construction of the theoretical framework of the two-level correction method.On the basis of summarizing the domestic and foreign scholars' researches on the quality of cultivated land,combine with the connotation of the quality of cultivated land,from the perspective of the production function of cultivated land,follow the logic of "function-process-factor" and draw on the "Land Evaluation and Site Assessment"(LASA)model,constructing a two-level correction method to analyze the characteristics of cultivated land quality level.(2)The establishment of two-level correction method index system and method.With the support of the LESA system,the natural quality evaluation index system of cultivated land is composed of the agricultural land classification factors recommended in the Agricultural Land Classification Regulations.The arable land site condition evaluation index system consists of five factors that reflect the basic conditions of high-standard basic farmland construction,field conditions,soil fertility and location conditions.On this basis,the grading total score is calculated by the method of assigning weights by grading factors and rating factors,and finally the total score is corrected by the standard production potential index and the comprehensive utilization coefficient,thereby determining the grading index and dividing the cultivated land.(3)Taking Gushi County of Henan Province as the research object,the two-level correction method is used to evaluate the quality of cultivated land in Gushi County.The final calculated grading index range is[787.28,1987.2],which is divided into 6 levels by the natural break point method.The average grade of cultivated land quality in Gushi County is 2.42.In general,the first-grade and second-level cultivated land with better cultivated land quality in Gushi County accounted for a larger proportion,followed by medium-quality third-level and fourth-grade land,and the poor quality five-level and six-level land areas are the least.From the statistics of various class levels,the average level of paddy fields is the highest,2.39,followed by irrigated land,2.57,and the dry land is 2.76.From the perspective of spatial analysis:the overall quality level of cultivated land in Gushi County has gradually declined from north to south,and a small amount of lower levels have appeared in the west.(4)Compare and analyze the two-level correction method and the procedure revision method results.The results show:The two-level revised statutory level has a better interpretation of the cultivated land production capacity than the procedure revision method.The coefficient of variation of each grading index in the procedure revision method is higher than the two-level correction method,and the level of the two-level correction method is more scientific.Through the spatial analysis of the level difference of the two methods,it can be seen that the two-level correction method can comprehensively reflect the differences in the quality of cultivated land.(5)Compare and analyze the results of the two-level revised statutory level and the results of agricultural land classification.The results show:The correlation coefficient between the national natural index and the grading index is 0.706;the correlation coefficient between the national utilization index and the grading index is 0.866;The difference between the analysis quality index and the grading index shows that the two-level correction method can refine the higher and lower arable land,and the level of equal differentiation is larger.Therefore,it indicated that the two-level revised statutory level can better reflect the impact of high-standard basic farmland construction on cultivated land quality than agricultural land classification.