江苏省粮食单产空间差异的因素分解

Decomposition Analysis for Spatial Variation of Grain Yield Per Hectare in Jiangsu Province

区分粮食单产空间差异的来源,是粮食单产空间特征和成因机制研究的一个基础问题,可以为粮食促产政策的制定提供较为可靠的依据。基于粮食作物配置的视角,以江苏省为例,运用因素分解法,探讨粮食单产空间结构及单产变化空间差异的贡献因素。结果表明:1)当前江苏省粮食作物配置结构的空间差异可以说明近80%的粮食单产的空间差异,而江苏省粮食生产力的空间分布与粮食单产空间差异仅低度相关。2)1990s中期以来,江苏省粮食单产增幅有南弱北强的倾向,主要来源是生产力效应,结构效应对这种空间分化起到强化作用。因此,相对于笼统的粮食单产指标,排除结构因素的粮食生产力因素能更为准确地体现粮食现实生产力的变化。

Spatial variation in grain yield per hectare comes from two sources： differences in the yield levels of each crop, and differences in the composition of cropping types. To discern such two sources is the basis for the study about spatial characters, mechanisms or zonal policies of grain yield. Grain yield and its change are decomposed into productivity effect and composition effect with the case of Jiangsu province. The results show that variance in composition of grain crops accounts for nearly 80 per- cent of the variance in grain yield, while there is a weak positive correlation between productivity index and grain yield. North Jiangsu has more grain yield increment than South Jiangsu since mid-1990s due to productivity effect, which strengthened by composition effect. It is thus argued that the productivity measure excluded from the influence of composition factor could in- crease the precision of estimate compared to the average grain vield that are used in much of the literature.