Physical fractionation techniques

Physical fractionation methods enable the separation of soil organic matter fractions that differ in their function, formation pathways, and persistence in soils. Several different physical fractionation methods have been developed to separate different components of soil organic matter by either particle size, particle density, or a combination of these characteristics. Here we summarize these techniques, providing first a conceptual framework for the fractions that are isolatable, and then describing the variety of methods that have been used by researchers to differentiate various fractions.