PROVINCIAL DIFFERENCE IN CULTIVATED LAND AND GRAIN PRODUCTIVITY IN CHINA

China's cultivated area has decreased steadily since 1957. In order to feed more and more people and to assure grain self-sufficiency in general, we have to improve yield of farm crops per hectare and keep certain area under cultivation. This paper has revealed the provincial difference, the quantity change of cultivated area and grain productivity change according to the data of long-series statistics of cultivated area, multiple cropping index, and grain yield during the past 50 years. This paper puts forward the conception of ratio of provincial's grain productivity to national average, and has quantitative analysis of the comparatively weightiness of cultivated land's grain productivity in every province, which is expected to provided scientific foundation for making-decision of protect cultivated land. There're obvious provincial difference in cultivated area and grain productivity change since the founding of New China. The regional difference of cultivated area change indicates higher productivity cultivated area decreases while lower productivity cultivated area increases. The cultivated area's grain productivity becomes small from south-east to north-west part in China. The highest cultivated area's grain productivity is located in the region of the middle and lower reaches of Yangtze River. Decrease of these provinces' cultivated land will exert greater influence. The driving forces for the decrease of cultivated land's grain productivity in south-east are lower comparative benefit, fewer cultivated land, denser population, and falling multiple cropping index.