Feasible potential of cultivated land quality promoted by land consolidation project

Abstract: In order to scientifically calculate the feasible potential quality of cultivated land quality upgrade and improve the planning, design, and arrangement of land consolidation project, a new pre-evaluation method of promotion potential of arable land quality was proposed based on the natural grade and utilization grade index of agricultural land gradation. The existing evaluation methods of improving potential of arable land quality are generally based on the natural grade and utilization grade index, and to set the top grade of arable land in a specified region as the target value of promotion potential calculation. The principle of existing methods is to assume that the limiting factors of arable land quality could be reduced or improved by land consolidation project. However, this assumption is not verified. This might cause the overestimate or underestimate of the evaluation results. The method we proposed was based on improvable degree of sensitive factors of agricultural land gradation. By investigating and analyzing how well the relative techniques of land consolidation can improve the sensitive factors of agricultural land gradation, the difference value between realizable and actual natural grade can be accurately calculated. The utilization grade could be calculated based on the natural grade. The first step was to implement a targeted survey to determine the sensitive factors of agricultural land classification, such as the effective thickness of soil layer, degree of salinity, drainage condition, irrigation guarantee rate, irrigation water source, rock coverage of surface soil, and slope gradient. Afterwards, we analyzed the magnitude of the change of each sensitive factor improved by land consolidation project based on the gradation unit. The second step was to analyze the feasible natural quality grade promotion attributed to the most effective engineering measure for calculating the promotion situation of natural and utilized quality grades by upgrade potential models of natural and utilized grades. Finally, we converted results of the first two former steps into the feasible upgrade potentials of natural and utilized grades. Zhongjiang County of Sichuan Province was taken as a case study for our method. After analyzing the previous achievement of agricultural land gradation, the effective thickness of soil layer, slope gradient and rock coverage of surface soil, drainage condition and irrigation guarantee rate were determined as the sensitive factors of arable land quality. According to the adaptability of every sensitive factor, lifting scheme was enacted. Results showed that, both natural and utilized grade of 60 grading units in the studied area can be improved after the implementation of land consolidation project. The promotion ranges of provincial natural and utilized grades were 171.24 to 605.34 and 89.30 to 232.96, respectively. The provincial natural quality grade was promoted by an average of 0.66, and the provincial utilized grade was improved by an average of 0.63. After converting the provincial grade into national grade, the national natural quality grade was improved by an average of 0.84, and the national utilized grade was improved by an average of 0.62. The pre-evaluation method we proposed was adapted to the local situation of consolidation, with which pertinence focus on the cultivated land quality upgrade was obviously after the implementation of land consolidation projects, and was conformed to the practical situation of local land consolidation project. Research results could provide references for the future planning and design land consolidation project and the promotion of cultivated land quality.