江苏省土壤有机质变异及其主要影响因素

土壤有机质在陆地生态系统中具有重要作用,是估算土壤碳储量、评价土壤肥力和质量的重要指标。从省域尺度上分析土壤有机质的分布和变异,及其影响因素,对节能减排和土壤的可持续利用具有重要的指导意义。以江苏省第二次土壤普查的1519个土壤剖面数据为基础,分析了江苏省表层(0-20 cm)土壤有机质分布、变异及其影响因素。结果表明,全省土壤有机质平均含量为(16.55±8.49) g/kg,变异系数为51.36%,属中等变异水平。不同土壤类型有机质含量差异较大,沼泽土最高,为31.60 g/kg,棕壤最低,为8.69 g/kg;自然土壤的有机质含量变异程度大于耕作土壤。年均温、年均降雨量、成土母质、土地利用、土壤质地和土壤pH对全省土壤有机质含量变异的综合能解释能力为52.6%。土壤质地和年均温是有机质含量变异的主要影响因素,土壤质地对其变异的影响大于年均温,二者能够独立解释其变异的32.0%和23.4%。

Variability of soil organic matter and its main factors in Jiangsu Province

In the terrestrial ecosystems, soil organic matter (SOM) plays an important role in estimating soil C sequestration potential, soil fertility and quality, etc. In this study, Jiangsu Province was chosen as an example in eastern China and a total of 1519 soil profiles were collected from the Second National Soil Survey of Jiangsu Province. And furthermore, the variability of SOM in the surface layer (0-20 cm) of Jiangsu Province was analyzed; and its main factors, too, by means of variance analysis and regression analysis. The results show that the SOM content of the region varied in the range of (16.55±8.49) g/kg, with a coefficient of variation of 51.36%, both belonging to a moderate level. SOM content of different types varies widely, with the maximum value of 31.60 g/kg in boggy soil, and with the minimum value of 8.69 g/kg in brown soil. The variation degree of SOM in natural soil was higher than that in cultivated soil. Analysis of variance suggests that mean annual temperature (MAT), mean annual precipitation (MAP), parent material, land use, soil texture and pH significantly affected the variability of SOM in Jiangsu Province. All these 6 natural factors can explain 52.6% variability of SOM. Soil texture and MAT are the main factors controlling variability of SOM. The effect of soil texture on SOM variation is stronger than that of MAT, and two factors can independently explain about 32.0% and 23.4% variability of SOM, respectively.