02477naa a2200217 a 450000100080000000500110000800800410001902400430006010000160010324501580011926000090027752017750028665000220206165000240208365000170210765000130212465000260213770000170216370000160218077300630219618686392017-08-03       2010    bl uuuu     u00u1 u    #d7 adoi:10.1016/j.soilbio.2009.08.0202DOI1 aKASCHUK, G.  aThree decades of soil microbial biomass studies in Brazilian ecosystemsblessons learned about soil quality and indications for improving sustainability.  c2010  aSoil microbial biomass plays important roles in nutrient cycling, plant?pathogen suppression, decomposition of residues and degradation of pollutants; therefore, it is often regarded as a good indicator of soil quality. We reviewed more than a hundred studies in which microbial biomass-C (MB-C), microbial quotient (MB-C/TSOC, total soil organic carbon) and metabolic quotient (qCO2) were evaluated with the objective of understanding MB-C responses to various soil-management practices in Brazilian ecosystems. These practices included tillage systems, crop rotations, pastures, organic farming, inputs of industrial residues and urban sewage sludge, applications of agrochemicals and burning. With a metaanalysis of 233 data points, we confirmed the benefits of no-tillage in preserving MB-C and reducing qCO2 in comparison to conventional tillage. A large number of studies described increases in MB-C and MB-C/TSOC due to permanent organic farming, also benefits from crop rotations particularly with several species involved, whereas application of agrochemicals and burning severely disturbed soil microbial communities. The MB-C decreased in overgrazed pastures, but increased in pastures rotated with wellmanaged crops. Responses of MB-C, MB-C/TSOC and qCO2 to amendment with organic industrial residues varied with residue type, dose applied and soil texture. In conclusion, MB-C and related parameters were, indeed, useful indicators of soil quality in various Brazilian ecosystems. However, direct relationships between MB-C and nutrient-cycling dynamics, microbial diversity and functionality are still unclear. Further studies are needed to develop strategies to maximize beneficial effects of microbial communities on soil fertility and crop productivity.  aMicrobial biomass  aSoil microorganisms  aSoil quality  aBiomassa  aMicrobiologia do solo1 aALBERTON, O.1 aHUNGRIA, M.  tSoil Biology & Biochemistry, Oxfordgv. 42, p. 1-13, 2010.