Research The Cultivated Land Of Sicchuan Province Based On Grain Security

Sichuan is one head province of grain production and consumption,which had4.2%cultivated land and6.8%population of China.In recent years,the pressure from grain security became more and more fearful, with the increase of population and decrease of cultivated land.So the study of cultivated land development change,grain productivity,regi-onal difference and discriminationg protection was important abstractly and realistically. This paper predicted and analyzed the supply and demand of cultivated land in Sichuan and each subarea in2010and2020by using GM(1,1) model and other models,based on the study of cultivated land development change in Sichuan during1996～2008.The results showed as follows.In2008, cultivated land area per capita of Sichuan had been below FAO alertness, which pricked up the imharmony between population and land.Dry land accounted for more than half of total cultivated land area.There was so much dry slope-land that returning to forest became the primary cause for the loss of cultivated land.Obvious regional difference appeared at cultivated land occupancy and change trend among21prefectures.Liangshan Autonomous State and Chengdu City had played the most important role in the total cultivated land loss of Sichuan Province during1996～2008.Total and per capita grain yield of Sichuan had been declining undulately. Grain yield per capita always towered above the average level of China in the same term.Based on the difference from cultivated land occupancy and grain productivity,21prefectures were divided into4subareas:subarea Ⅰ,Suining City etc.,5prefectures;subarea Ⅱ,Liangshan Autonomous State etc.,5prefectures; subarea Ⅲ,Chengdu City etc.,8prefectures; subarea Ⅳ,Ya’an City etc.,3prefectures.The self-supplying percentage of Sichuan and each subarea had been less and less.The forecast results from programming compendium of Chinese grain security during2008～2020by NDRC showed:grain consumption per capita of China would be389kg and395kg respectively in2010and2020,based on which the demand of cultivated land was forecast in this paper.In Sichuan,the condition of supply less than demand would appear in2010,and more serious in2020.In subarea Ⅰ&Ⅱ,the cultivated land could produce sufficient grain to feed the population.In subarea Ⅲ&Ⅳ, the self-supplying level was so low that more and more grain need importing.Improving land fertility could be able to indirectly increase the amount of cultivated land in virtue of scientific and technological progress.But the amount was very limited to subject to the law of diminishing returns constraints.To maintain a certain amount of cultivated land resources are the rigid requirements of grain security.Cycle-ARIMA linear combination model had strong adaptability for grain yield per hectare, grain sowing of cultivated land use index to show a cyclical increase (or decrease) the trend of time series analysis.The protection measures of cultivated land resources were proposed from the ecological,social,economic and technological point,based on the above findings between the supply and demand of each subarea.