Comparison of different soil organic matter fractionation methodologies: Evidences from ultrasensitive 14C measurements

In this study we present a series of Accelerator Mass Spectrometry (AMS) 14C measurements on SOM samples obtained by means of different laboratory protocols used for the isolation of soil pools from bulk soil (fractionation protocols). Radiocarbon signature of SOM fractions is used as a keyhole to look at the more effective fractionation procedure and comparison among measured 14C on SOM fractions revealed important indications for the proposal of a novel fractionation protocol. Our data put in evidence how particle size controls the recalcitrance of ancient SOM carbon pools.