关键词: 耕地利用, 集约度变化, 粮食安全, 耕地粮食生产效率

Abstract: The area of cultivated land in China decreased from 35×104ha/yr(1980-1996) to 98×104ha/yr(1997-2005),resulted from rapid economic development following the 1978 reforms.In response to the growing demand of society for grain products,intensification has become the overwhelming choice in cultivated land use.But this choice came into conflict with farmers' pursuance in recent years,as the grain production is declining in importance for farmers with market economic improvement.Has the cultivated land use been intensive or extensive in the conflict between social interests and individual interest.How to release the conflict if extensive trend exists. The intensity changes in cultivated land use were discussed firstly on country scale.Increase of multi-cropping index(MCI) during 1952-2005 implied the intensification in cultivated land use in this period.But the sown area of grain decreased from 113787000hm² in 1998 to 99410000ha in 2003 and 104278000ha in 2005.Meanwhile,the grain yield per unit-sown area had a reduction from 4502kg/ha in 1998 to 4332kg/ha in 2003,and then went up to 4642kg/ha in 2005.The downward trend of grain sown area and grain yield per sown-unit area during 1998-2003,revealed input reduction of cultivated land,expense and labor in grain production.The rise in 2004-2005 can be ascribed to the implement of new agriculture policy.Those facts mean that lower incentive for raising cultivated land use intensity already threatens grain production in China. On regional scale,the intensity in cultivated land use varied across provinces.MCI decreased in regional disparity in Beijing,Shanghai,Tianjin,Zhejiang,Fujian,Jiangxi,Hubei and Guangdong during 1996-2003.Furthermore,these provinces reduced their grain sown area synchronously.Other provinces that reduced their grain sown area included Hebei,Shanxi,Inner Mongolia,Liaoning,Jiangsu,Shangdong,Henan,Hunan,Guangxi,Hainan,Sichuan,Shaanxi,Gansu,Qinghai,and Xinjiang.Except for input reduction of cultivated land in grain production,input of labor and expense declined in some of the above regions till 2005. Farmer's pursuance change is at the root of the intensity change in cultivated land use.It had turned from maximizing the output of land to maximizing the income of labor force with the development of market economy.In order to achieve the goal of national food security,relevant policies and measures should be further taken to alleviate the conflict between the nation's goal and farmers' goal of maximizing their interests.These policies and measures should speed up the flow of cultivated land between farmers and encourage farmers to extend their farm scale with higher technological level.

Key words: cultivated land use, intensity change, food security, grain production