A MODIS data derived spatial distribution of high-, mediumand low-yield cropland in China

With the population increase and food consumption upgrade in China, the issue of food self- sufficiency attracts much attention from both Chinese government and international society. Under the circumstances of inadequate cropland resources supply and plenty of cropland occupied by urban construction, improving the utilization efficiency of arable land resources and increasing the cropland productivity have become the fundamental strategies of agricultural development in China. Since 1988, cropland improvement projects(medium-yield and low-yield field improvement and high-standard cropland construction) have been launched and implemented on a large scale, therefore a spatially explicit map for the distribution of high-, medium- and low- yield cropland was essential for cropland improvement planning. In this study, a new method for recognizing high-, medium- and low- yield field is developed based on cropland productivity, which is calculated by using a light use efficiency model and MODIS data with a 500- m resolution. This method can not only reflect the regional heterogeneity of cropland condition, but also express the spatial differences on a grid scale. At the same time, it effectively overcomes the shortage of statistical data based method in a county unit. The results show that the proportion of high-yield, medium-yield and low-yield cropland in China is 20.66%, 39.56% and 39.78%, respectively. About 3/4 of low- yield cropland is located in the hilly and mountainous regions, while 53% of the high-yield cropland is located in plain area. The five provinces with the largest area of high- yield cropland are Henan,Shandong, Jiangsu, Hebei and Anhui, which are all located in the Huang-Huai-Hai region. The sum of the high-yield cropland area in these five provinces accounts for 41.75% of the national total high-yield cropland area. In Heilongjiang province, Sichuan province and Inner Mongolia autonomous region, where the cropland area ranks the top three of China, the proportion of high-yield cropland area in each province only accounts for not more than 15%.