Valpassos, M.A.R. et al. 2001. Effects of soil management systems on soil microbial activity, bulk density and chemical properties. Pesquisa Agropecuaria Brasileira. 36, 12 (Dec. 2001), 1539–1545. DOI:https://doi.org/10.1590/S1678-3921.pab2001.v36.6288.