Soil microbial biomass plays an important role in nutrient cycling in soils. Among the several methods that have been used to estimate the soil microbial biomass-C (SMBC), chloroform fumigation incubation (CFI) and chloroform fumigation extraction (CFE) are the most studied. Although several studies in the literature have compared the efficiency of these two methods to estimate SMBC, there is little information for the acid soils of the Cerrado region. The present study compared the efficiency of these two methods in cultivated Cerrado soils (a corn-soybean rotation and a legume-based pasture) and neighboyring in soils under three native vegetation types (gallery forest, grassy savannah and woody savannah). Soil samples were collected at two depths: 0-5 cm and 5-20 cm. Sampling times were: August of 1998 and 1999 and January of 1999 and 2000. The results obtained in cultivated soils with the two methods were similar regardless of treatment and sampling time, however the interaction depth x method was significant. There were no differences between depths 0-5 cm and 5-20 cm with the CFI, whereas the differences observed with CFE were statistically significant. For soils under native vegetation, the results obtained with CFI and CFE were similar regardless of treatments, depth and sampling time. The Gallery Forest presented the greatest levels of SBMC as compared to grassy savannah and woody savannah. The interactions depth x methods and sampling time x methods were statistically significant, because differences were more pronounced with CFE. The results showed that both methods were appropriate to determine microbial biomass carbon in Cerrado soils.
soil microbial biomass; cerrado soils; gallery forest; grassy savannah; legume-based pastures; annual crops