Land Suitability Evaluation of Sorghum Planting in Luquan County of Jinsha River Dry and Hot Valley Based on the Perspective of Sustainable Development of Characteristic Poverty Alleviation Industry

Land suitability evaluation is the basis for optimizing and adjusting regional land use structure and layout, making scientific decisions, and planning, according to local conditions. It is also the basis for developing local characteristic poverty alleviation industries, and achieving sustainable development according to local conditions. However, existing research on the evaluation of land suitability rarely results in scientifically selecting the land resource area of a single crop, based on the principle of “suitable planting in the right place” and “suitable growth in the right place”; additionally, it does not conduct the land suitability evaluation of a single crop from the perspective of the sustainable development of the characteristic poverty alleviation industry. As the evaluation scope, this paper takes the dry and hot valley area of the Jinsha River, in Luquan County, Yunnan Province, as an example, selects eight evaluation factors, and organically combines the “limit condition method” and the “suitability index method”, determining 27,877.59 hectares of irrigated land, dry land, and other grasslands, below 1800 m above sea level in Luquan County in the Jinsha River basin. According to the principles of “suitable planting in the right place” and “suitable growth in the right place”, the suitability of sorghum planting land was evaluated. The evaluation results show that: the land area suitable for planting sorghum is 24,227.61 hectares, accounting for 86.91%. The area of land unsuitable for planting is 3649.98 hectares, and the area with a gradient over 25°, and obvious water and soil loss, accounts for 51.68% of the area of land being unsuitable for planting. The area of land unsuitable for planting is 48.32%, due to the restriction of soil thickness, soil texture, and bare rock, etc. The land that is not suitable for planting sorghum needs to be included in the scope of ecological protection. Compared with the 1200 hectares that have been developed and planted at present, there are still sufficient land resources suitable for planting sorghum. However, the area and proportion of land suitable for planting sorghum in different townships are quite different, so it is necessary to make a reasonable layout of the land suitable for planting sorghum according to local conditions. Among the land suitable for sorghum planting in the county, the proportion of the first, second, and third grade land suitable for sorghum planting is about 14:35:51. This shows that the area of first-class land suitable for planting is relatively small. This is because the terrain of the Jinsha River basin is characterized by: high mountains, steep slopes, deep valleys, little flat land, mainly mountains, shallow soil layers on slopes, and has poor texture. Therefore, there are many third-class suitable lands for planting with poor quality, and many reconstruction measures need to be taken to improve the quality of land suitable for planting.