Influential factors decomposition for China's grain yield based on logarithmic mean Divisia index method

Abstract: The premise for establishment of appropriate grain production policies is to analyze the contributions of different influence factors to the variation of grain production. However, the existing studies focus on the overall comparison of influence factors affecting the grain production in China, and thus cannot reflect the annual differences or changes. Therefore, in this study, we built a complete (zero residual) decomposition model based on logarithmic mean Divisia index (LMDI) method for investigation into grain production in China. With this model, the changes of grain production were decomposed into the contributions from four factors, including yield per cultivated area, planting structure, multi-cropping index, and changes of cultivated land area. Based on the data from 1996 to 2012, we decomposed and analyzed the factors affecting the changes of grain production in China during this period. The results showed that the total grain production in China generally increased from 1996 to 2012, but it also fluctuated at a severe rate inter-annually. From the perspective of increments, the effect size of yield per cultivated area was 85.9225 million t, and yield per cultivated area was a major influence factor promoting the increments of grain production in China. The effect size of planting structure was -39.0911 million t, and planting structure was a major influence factor inhibiting the increments of grain production in China. However, the effect of planting structure on grain production became strongly positive from 2004 to 2006, and planting structure was a major influence factor promoting the increments of grain production during this period. From the perspective of fluctuation, the fluctuation of grain production in China from 1996 to 2003 was mainly attributed to the effect of yield per cultivated area and the effect of planting structure. From 2004 to 2007, the effects of yield per cultivated area, planting structure and multi-cropping index on grain production were contributive alternatively, but no effect was absolutely dominant. Since 2008, the effect of yield per cultivated area and the total effect changed in very similar ways. The results above show that the effect of yield per cultivated area is mainly responsible for the changes of grain production in China at the current stage, while the effect of planting structure can be enhanced greatly in the future. Moreover, the effect of multi-cropping index will not bring about great changes, but its sudden reduction may cause fluctuation. In comparison, the effect of cultivated land area can be ignored. Thus, regarding how to enhance China's grain production ability in the future, the main developing trends are to stably improve the yield per cultivated area, to raise the enthusiasm of peasants for grain production, to modify the planting structure, to prevent natural disasters, and to avoid the abrupt changes of multi-cropping index. These findings provide some valuble information for relevant governmental departments to establish grain production development plans and to formulate related industrial policies.