Measuring soil microbial biomass using an automated procedure

Here we outline the development of the first automated procedure for measuring soil microbial biomass carbon (biomass C) by Fumigation–Extraction (FE) and on which this Citation Classic is based. The method (and its later variations) has been used widely since it was published. It gives essentially the same results as the Fumigation–Incubation (FI) method on which it was based and which it has now largely replaced. Analysis of the current data clearly showed that the calibration value to convert extracted organic C to biomass C (kEC = 0.45) using FE is still valid and that there was no need for a change. We also review some of the previous discussions about the method and outline future prospects for microbial biomass measurements in soil microbial ecology.