Potential Capacity of Cassava Planting in Guangxi: Assessment of Natural Suitability and Socio-Economic Restrictions
广西能源作物木薯种植的可能规模：自然适宜性与社会限制性评价

Because of the fast consumption of fossil energy and associated environmental problems, governments have paid increasing attention to the development of the bio-energy industry. The Chinese government has formulated a series of policies to improve the bio-energy industry. In order to ensure the food security, the Chinese government has claimed that bio-ethanol could only be produced by non-food crops such as sweet sorghum and cassava. Cassava is a type of non-food crops and one of main materials of bio-ethanol production. With the increasing demands for cassava in Guangxi Zhuang Autonomous Region, which is the most important traditional cassava planting area, relevant institutions and government departments are paying increasing attention to the cultivation potential of cassava. In this paper, based on climate suitability, soil suitability, terrain suitability, and socio-economic restrictions of land use, we used the AHP method to evaluate the suitability of each index. Then, the suitability of comprehensive indexes was evaluated. At last, an assessment of its natural suitability and social restrictions of cassava planting in Guangxi was conducted, with its land production potential, potential capacity, and spatial distribution being quantitatively analyzed. Results show that among all indexes, the terrain condition was the leading limiting factor of cassava planting potential, followed by the soil condition. If the socio-economic restrictions of land use were not accounted for, 60% of the land area in Guangxi was suitable for cassava planting. On the contrary, the suitable land area would decrease to 1 155 ×103 ha. Compared with current plating area of 223 × 103 ha, there were up to 4 times cultivation potential. Concerning the spatial distribution, the key areas of cassava planting in the future are in the region of Liuzhou and Laibin. It is suggested that developing the bio-ethanol industry based on cassava in Guangxi would be a right choice, but the development speed should keep appropriate and the extensive mode of production has to be shifted to an intensive mode. Second, although the main areas of cassava planting are in Nanning, Wuzhou, and Guigang, the potential planting areas are Liuzhou and Laibin. Third, more emphasis should be placed on the environment and economy of cassava planting, because much waste grassland and unutilized land were not fully utilized to plant cassava, they would cause serious soil erosion. Its influence on other industries of cassava cultivation should be evaluated.