Discrepancies in utilization of density fractionation along with ultrasonic dispersion to obtain distinct pools of soil organic matter

Density fractionation along with ultrasonic dispersion is widely applied in soil science to obtain distinct fractions of soil organic matter. Density cut-off and dispersion energy are crucial parameters to yield fractions closely corresponding to their conceptual definitions. Our literature review revealed methodological discrepancies in the utilization of density-fractionation schemes. Strikingly, reasons for the selection of specific density or dispersion energy were rarely explained. Thus, it is not known how results of different approaches relate to each other. We therefore recommend testing and reporting effects of fractionation parameters on chemical and physical properties of fractions, to achieve agreement and coherence on parameters to be used and facilitate comparability in future studies.