Construction potential of high-standard farmland based on landform factors

The construction of high-standard farmland is important for scientific, efficient and sustainable use of land resources, and the potential study is the basic work in the construction of high-standard farmland. In view of the experience and problems in the construction of high-standard farmland during the "12^th Five-Year" period, this study hypothesized that "high-standard" not only focused on the quality improvement, but also the enhancement of mechanization and scale of cultivated land. Moreover, differentiation was necessary in planning and design for various natural, social and economy conditions. There are complex and diverse landform types in Chongqing. Driven by the law of regional differentiation, significant differences in social-economy and industrial development arose in space. Thus this article used landforms as the basis for evaluation of high-standard farmland construction potential with Dianjiang County in Chongqing as the research area. The study analyzed the potential of using basic farmlands to build high-standard farmlands and isolated the limiting factors for building high-standard farmlands in different landform types. Hence it was expected that the study will provide the theoretical basis for the planning and construction of new high-standard farmlands in Dianjiang County, Chongqing. Based on the four landform areas of Dianjiang County (shallow and low hill area, low middle hill area, high hill with flat area, and low mountain and deep hill area), we established an index system to evaluate the construction potential of high-standard farmlands. Furthermore, the entropy weight method was used to calculate the weights of indicators in each geographic area. The comprehensive index method was further used to determine the potential score of each evaluation unit. The results showed that:1) about 80% of the basic farmlands in Dianjiang County had the potential to be transformed into high-standard farmlands. Among these, the area basically meeting the construction criteria covered 28.57% of the total basic farmland, the area needing improvement accounted for 24.13%, and the area needing comprehensive renovation made up 26.92%. 2) The potential for the construction of high-standard farmlands in four types of landform was ranked as:shallow and low hill area > low middle hill area ≈ high hill with flat area > low mountain and deep hill area. 3) There were different limiting factors to high-standard farmland construction in different landform areas. The restricting factors in the shallow and low hill area were soil organic matter content and farmland protective acreage. The limitations in low middle hill area were effective soil layer thickness, soil organic matter content, and irrigation and drainage conditions. The restrictive factors in the high hills with flat area were soil organic matter content, irrigation and drainage conditions, and distance of field to main road. The limiting factors in low mountains and deep hill area were effective soil layer thickness, soil organic matter content, pH, irrigation and drainage condition, farmland tractor-plowing ability, and distance of field to residential area. In the planning and implementation of high-standard farmland construction projects, there was need for project layout to be closely developed around different physiognomy type restriction factors and local agricultural industry development direction. At the same time, there was need for project layouts to focus on leading industries and to eliminate or reduce the role of limiting factors, to carry out different high-standard farmland constructions.