Modified method for gradation on agricultural land quality in land remediation project areas

Abstract: Land remediation is an effective measure to improve land-use conditions and land quality. In the updated work of gradation on agricultural land quality, the existing gradation system cannot reflect the changes before and after land remediation projects. The paper proposes a new gradation system that can reflect the land quality changes before and after projects. The new gradation system adds two times of modification to the original gradation system. The first is to select the engineering factor of land remediation that influences the physical quality, obviously to calculate the modified coefficient of physical quality. The factors include terrain slope, outcrops of surface, probability of irrigation, and drainage condition. The second, select the land use factors which influence the utilization quality to calculate the modified coefficient of land use. These factors include regularity of plots, roads in croplands, patterns of irrigation, and patterns of drainage. Then the paper analyzed land remediation projects in Luliang County to verify the new gradation system. It selected 14 points that lay in the land remediation project areas. The results showed that: 1) Physical quality. 5 of 14 points' physical quality promoted a little, and the average promotion was 0.1 grades. The other 9 points did not change. 2) Utilization quality. Utilization quality of all the 14 points was promoted. The average promotion was 1.1 grades. The least was 0.5 grade and, the most was 1.7 grades. 3) Economic quality. Economic quality of all the 14 points was promoted. The average promotion was 1.1 grades. The least was 0.4 grade, and the most was 1.8 grades.It comes to a conclusion that: Taking the new gradation system of adding the modified coefficient of physical quality and the modified coefficient of land use to the original gradation system to be the gradation method for cultivated land in land remediation projects areas is feasible.