Cultivated land quality evaluation of land consolidation project based on agricultural land gradation

Abstract: To improve the quality of cultivated land was one of the core tasks of land consolidation. But for a long time, increasing the number of arable land was the only goal, and therefore it was an urgent requirement to effectively and quickly evaluate the consolidated farmland's quality for the research and practice on the basis of ready data. To stabilize the amount of arable land, improve the quality of arable land and ensure food security were the main objectives and focuses of the agricultural land consolidation in China currently. Monitoring the changes in number and quality of arable land was objective requirement to guarantee the orderly development of the system. Agricultural land classification (ALC) fully ascertained the distribution of Chinese farmland quality level and established a unified national database of cultivated land quality grades. The Ministry of Land and Resources (MLR) deployed the dynamically updated work of cultivated land quality grade change in 2012, which provided solid foundation for the scientific management of land quality. But ALC mainly characterized the quality of farmland at macro level, and the application of the results faced some restrictions on the scale of the project. Therefore, the evaluation system of classification needed to be corrected. Land consolidation included four projects: land leveling project, irrigation and drainage project, field road project, farmland protection and eco-environment maintaining project. This paper analyzed the impact of these four projects to the farmland quality, distinguished the sensitive factors and stable factors, supplied the modified factors for natural quality and production condition through comparing with the ALC. Combined the factors of natural quality and ALC, the corresponding weights were set by AHP(analytic hierarchy process) and Delphi, the natural quality evaluation system was constituted based on project scale, and natural quality score was recalculated. Light and temperature potential, yield ratio coefficient, utilization coefficient and economic coefficient were regarded as constant values. The natural quality index was recalculated, and the natural grade of arable land on project scale was classified. Follow the idea of revising coefficient, compare the scores of the production factors before and after the consolidation, calculate the correction coefficients of utilization and redraw the utilization grades. Because land consolidation projects did not directly affect agricultural production technology and management level of arable land, this study did not involve economic correction. Finally, combined with field survey data in the study area, the correlation between the obtained results and the actual output was analysed, and the validity of this evaluation results was verified. Taking Lingshui county, Hainan province as an example, this article analyzed typical land consolidation project. The research results demonstrated that the comprehensive nature grade increased from 4.7 to 4.2, the comprehensive utilizable grade increased from 4.3 to 3.2 and the correlation coefficient between consolidated utilizable grade index and actual output of benchmark crops was 0.86, which was higher than the one before the revision 0.82, indicating that the constructed cultivated land quality evaluation system can effectively reflect the land consolidation's impact on the farmland quality and the analysis results meet the need of objectively evaluating the change of farmland quality. This study can provide the reference for cultivated land quality evaluation.