Spatial Pattern Change and Its Driving Factors of Grain per Unit Area Yield in Northeast China

As one of the most important commodity grain bases in China,Northeast China plays a very important role in ensuring national grain security.Based on the statistical data of 183 counties in Northeast China,spatial pattern of grain per unit area yield in the 1980s,1990s and the early 21st was discussed.The purpose of the study is to discover the regional difference and spatial characters of grain per unit area yield change.Five spatial types are divided according to the coupled conditions of grain per unit area yield and its increasing ratio.The results show that: 1) Counties with grain per unit area yield above national average levels are concentrating in black soil zone of Songnen and Liaohe Plain region;but counties with grain per unit area yield below national average levels are concentrating in the northern part of Northeast China,eastern hilly areas and the Sanjiang Plain region.2) Grain per unit area yield takes on increasing trend by and large,and counties that grain per unit area yield increased are in domination,accounting for 83.61% of the total number of the counties.3) Regional difference is very obvious in variations of grain per unit area yield among the counties,inverse to the lower grain per unit area yield counties,regions with higher grain per unit area yield takes on an increasing trend as a whole.However,it takes on a regional difference before and after 1990s: region with grain per unit area yield above 6000 kg/hm2 increases continuously,and region with grain per unit area yield between 3000 kg/hm2 and 6000 kg/hm2 enlarges by and large,but witnessing a course of enlargement to lessen;and region with grain per unit area yield below 3000 kg/hm2 experiences a continuous decreasing course.4) Grey correlation analysis shows that the most important factors affecting variation of grain per unit area yield are the total power of agricultural machine,total consumption of chemical fertilizer,effective irrigated area,and price factors.However,the influence of natural disaster and net income of per farmer should not be ignored.5) According to grain per unit area yield of 1980 and its average increasing ratio from 1980 to 2005 of the counties,five spatial types can be demarcated,which include better foundation-faster development region,better foundation-slower development region,and weaker foundation-faster development region,weaker foundation-slower development region and weaker foundation-minus increase region.It is an important way to improve grain per unit area yield by accelerating construction of agriculture modernization and strengthening reconstruction of medium-low yield farmland in order to ensure progress of comprehensive grain production ability and enhance the ability of ensuring national grain security.