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.