Suitability evaluation of suitable-for-mechanization transformation of cultivated land based on topographic complexity in Chongqing, China

Suitable-for-mechanization transformation is the fundamental way to promote the development of agricultural mechanization in hilly areas. Scientific evaluation of its suitability can reasonably plan the transformation process, which is significant in improving the efficiency and accuracy of agriculture mechanized transformation in hilly areas. The study selected three topographic limiting factors: elevation, slope and fragmentation with different districts and counties in Chongqing as evaluation units, to evaluate the suitability of suitable-for-mechanization transformation of cultivated land by integrating GIS spatial analysis function and data envelopment method (DEA). The results showed that: 1) the cultivated land plots in Chongqing was small and fragmented, mainly distributed in the central and western regions. The area and density of cultivated land in the eastern part of Chongqing were obviously less than that in other regions, consistent with the topography of high in the east and low in the west. The spatial distribution characteristics of paddy field and cultivated land were similar, and the terrain requirement of dryland was lower than that of paddy field. 2) The cultivated land was mainly distributed in the slope of 6°−15° and the elevation of 200−500 m, among which the cultivated land with the elevation of 300−400 m was the most ideal area for mechanization transformation, accounting for 48.88% of the main cultivated land. 3) According to the classification method of natural disjunctions (Jenks), the comprehensive topographical complexity index was segmented into six sections of the suitability degree of mechanization reconstruction in Chongqing City including very suitable, suitable, relatively suitable, relatively unsuitable, unsuitable and very unsuitable. The average value of terrain complexity index of each district and county was 0.925, and a total of 25 districts and counties were below that index, including 9 districts and counties in the very suitable area such as Tongnan District, 7 districts and counties in the suitable area such as Bishan District, and 9 districts and counties in the relatively suitable area such as Qijiang District, which were relatively suitable. The evaluation results, which consider the limiting factors of developing the agricultural mechanization of hilly areas, were highly coincident with the actual geomorphic layout of Chongqing City, which was conducive to group integrated development. So it is suggested that the places with high suitability should be given priority for mechanization reconstruction for further landing. Therefore, the suitability evaluation method based on the terrain complexity can effectively evaluate the suitability of hilly mountain land in reconstructing appropriate machine for cultivated land, with the support of GIS spatial analysis function. Futrthermore, the appropriate machine renovation for the cultivated land located in a region of gradient less than 15° will greatly improve the degree of agricultural mechanization in Chongqing municipality; thus, the appropriate machine reconstruction for cultivated land is potential.