Space-time Change And Convergence Of Rice In Lowland Rice Farming System

Food security is the fundamental basic for ensuring healthy and rapid development of China's economy.China is a big country either in grain production and consumption,or population.Rice,as one of the most important food crops,plays an important role in maintaining China's food stability and national security.Lowland rice farming system is an important rice production system in China.Analysis on yield change and growth patterns of this system helps to observe the national dynamic changes of rice production.Based on the research outcome raising the rice production capacity of the system is of great significance for further safeguarding regional and national food security,increasing farmer household income,and promoting rural economic development.In this paper,the ESDA and spatial convergence methods are used to analyze the yield changes of rice in more than 400 counties in the Lowland Rice Farming System from 1980 to 2014.The descriptive statistics,Moran statistics and LISA cluster diagram are used to investigate the convergence of rice yield.The spatial-temporal evolution,spatial autocorrelation and spatial differences of rice yield per unit area in the county of the system,and county spatial absolute β convergence test have been done in the system.The spatial club convergence test was performed on two different spatial autocorrelation regions of H-H and L-L.Based on the spatial convergence test,typical cities and counties are selected for convergence verification in the two agglomeration areas.The analysis of the convergence from qualitative and quantitative aspects of Jiangsu Province,a representative province of H-H cluster,and Jiangxi Province,the representative province of L-L cluster,are carried out.Finally,we make trend judgments on regional future rice yields and analyze the risks and challenges that rice production may encounter.The results of the study show that the overall rice yield in the lowland rice farming system increased significantly from 1980 to 2014,and the sown area and yield of rice increased significantly.In the four time periods of 1980-1982,1990-1992,2000-2002,and 2012-2014,the change in yield of the county appeared obvious spatial agglomeration,but it also show significant spatial differences.There is a range attenuation effect on the spatial distribution of rice yield.An absolute β convergence and spatial club convergence in rice yield has been observed in the county level.Compared with the H-H autocorrelation region,the rice yield in the L-L autocorrelation region converges to a lower level,and the rice yield in the two regions is faster than the average convergence rate in the entire region.The results also show that the differences in rice yields between regions are affected by various factors such as the technical level,cooking system and climate.Though the regional differences in yields still exist,but this difference has gradually narrowed.In the area of H-H agglomeration of rice yield,we should expand the radius of influence of rice yield-benefit area,promote the transfer of agricultural technology,and increase the yield of rice in the surrounding areas.Minimize intra-group and inter-group gaps of the rice yield in both H-H and L-L areas as much as possible to improve the overall capacity of regional rice production.In recent years,rice production has been affected by many factors.It is necessary to stabilize rice sowing area,use production factors such as chemical fertilizers and pesticides reasonably,increase R&D and promotion of new rice varieties,reduce the instability of rice production due to climate warming to excavate rice production potential and promote rice yield increase.