Temporal-spatial changes of planting structure from main grain crops in Northeast China

With the agricultural supply-side reform, the research on reasonable temporal-spatial change of cropping patterns at regional scale will provide guideline for adjusting and optimizing crop structure in Northeast China.Based on the planting acreage data from main crops at city/league level from 2005 to 2015, we used mathematical statistics to examine cropping types by the acreage proportion and their combination, thus made an analysis on temporal-spatial change of main grain crop structure in Northeast China.The results showed that:(1) The total grain sown area kept increasing in Northeast China from 2005 to 2015, both the seeding area and proportion of soybean experienced a wave of "ascent-descent", while the seeding areas and proportions in maize and rice steadily expanded and that of rice exceeded soybean in 2011.(2) We found 8 cropping types in Northeast, which gave a priority to dominant-crop type; the number of the dominant maize and rice types kept increasing while that of the dominant soybean decreased.(3) The dominant maize area widely spread from Liaoning province and Jilin province to the center and east of Heilongjiang province while the dominant soybean area narrowed to Xing'an Mountains regions.Therefore, the crop structure obviously transferred to maize, which happened in the center and east of Heilongjiang province, eastern Jilin province and Hulunbuir of Inner Mongolia.