Study On Cultivated Land Carrying Capacity Based On Human-grain Relationship In Hunan

Based on human-grain relationship, this study estimated the potential land productivity of the staple food crops in Hunan by applying environmental elements step up method. The situation of cultivated land carrying capacity and human-grain relationship in Hunan were studied by using the model of land carrying capacity and land carrying capacity index. The food security and the predictive evaluation of cultivated land carrying capacity in Hunan were studied systematically by analyzing the human-grain relationship level of each county.1. The potential land productivity of Hunan is 18452.79 kg/hm2 with the index of 0.660, leaving 2/3 under development. The areas with higher potential land productivity mostly distribute in the north-central and east-central parts of Hunan, while the areas with lower potential land productivity distribute in the east and southwest. The areas with higher index of potential land productivity mostly distribute in the plain area of Dongting Lake and the middle of Hunan, where the soil is fertile, with an index of over 0.73. However, the index in the north, southwest and southeast areas is lower, parts lower than 0.53.2. Under the present productivity level, Hunan can carry a population of 74.233 8 million and the index is 0.922, with a basic balance human-grain relationship. The areas having surplus grain mostly distribute in the middle and the north of Hunan. Most parts of the south area are going to face an overload population. In the west of Hunan, especially in Jishou, Guzhang and Luxi County, the population is overloaded with a strained man-land relationship. From 2000 to 2008, the index of cultivated land carrying capacity in Hunan varies from 0.9 to 1.1 with the situation of remaining balance in an abundant year and facing overload in a bad year. Especially in 2002 and 2003, it has overloaded 3.752 5 million and 5.559 8 million. Therefore, to make sure of the food security, the grain productivity should be increased.3. Based on the prediction of grain-sown area, the grain output of per unit area and the population scale in Hunan, the cultivated land carrying capacity based on human-grain relationship in 2015 and 2025 were estimated. According to the results of prediction, Hunan can carry a population of 75.215 2 million at the food consumption level of well-off in 2015 with the index of 0.953, and 72.817 4 million at the level of better-off in 2025 with the index of 1.051. According to the situation of agriculture development, it could satisfy the demand of people and reach the well-off standard in 2015 with a basic balance human-grain relationship. However, to secure a better-off life in 2025, the population would be overloaded. From this point of view, the potential land productivity should be developed and the grain output of per unit area should be improved meanwhile, in order to improve the living standards under the food security.