The potential of soil microbial biomass measurements as indicators of soil bioactivity and interferences in this environment can be verified by the amount of published papers on the subject. Nevertheless, a comparison among data from different authors, regions, and soils is only possible when the methodology employed in the determinations is the same. Several papers, however, propose different methodologies and calculations. This study evaluated the results of microbial carbon determination by different extraction and digestion methodologies in two distinct soils. It was also performed biomass calculations, besides calculations for indirect transformation of CO2 from basal and induced respiration into microbial carbon in the two soils. Results varied greatly among methods and calculations, and the conclusion was drawn that the most frequently used methodology (Vance et al., 1987) should be adopted for a valid comparison of the amount of microbial carbon among soils and literature data.
microbial carbon; extraction; digestion; respiration
