土地整治项目提升耕地质量可实现潜力测算

耕地质量潜力测算是土地整治项目设计的基础工作，其测算方法有待进一步研究。该文依据农用地分等方法和数据，利用自然等指数、利用等指数，构建可实现潜力测算模型，测算出经土地整治后自然等、利用等别提升的可实现潜力。以中江县土地整治项目进行了实证研究，在利用预评价法对项目区分等因素可改变和消除的幅度进行了可行性分析的基础上，测算了项目区耕地质量可实现潜力。结果表明，整治后项目区自然及利用等指数均可有所提升，分等单元的省自然等、利用等指数提升区间为171.24～605.34、89.30～232.96，国家自然等、利用等指数提升区间为161.10～471.67、62.26～162.09。按照划分等别区间分值转换后，省自然等、省利用等、国家自然等、国家利用等分别平均提升0.66等、0.63等、0.84等、0.62等。该研究方法符合当地土地整治实际情况，提高了耕地质量潜力测算的应用性，可为土地整治项目设计编制和耕地质量建设提供参考。

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.