Advance of Research on Fractionation Methods of Soil Organic Matter

Soil organic matter(SOM) consists of various functional pools that are stabilized by specific mechanisms and have certain turnover rates.In the past,numerous fractionation schemes have been developed to separate and analyse such SOM fractions.Fractionation methods include physical and chemical separation of SOM Furthermore,combinations of fractionation methods are evaluated.The active SOM pool may best be represented by the soil microbial biomass,the light fraction organic matter and particulate organic matter.Most chemical and physical fractionations as well as combinations of methods yield SOM fractions that are not homogeneous in terms of turnover rates.The available fractionation methods do not correspond to specific stabilization mechanisms and hence do not describe functional SOM pools.The use of microbial biomarkers and compound-specific isotope analysis is important for future differentiation and evaluation of functional SOM fractions.