Different sites of an iron mining from Mariana, Minas Gerais, Brazil, were evaluated for determining the degree of their degradation or reclamation, using microbial activity of soil, spore numbers of arbuscular mycorrhizal fungi (AMF) and total count of fungi and bacteria. Each site contained a substrate characterized as flotation refuse (Rj), Soil without vegetation (SS), Subsoil (Ss), Subsoil with vegetation (SsV), site under recuperation (AR) and forest (MS), and was sampled at 10-25 cm. Establishment of grasses and "candeia" (Vanillosmopsis erythropappa Schult. Bip.) plants in subsoil samples increased spore number of AMF, organic carbon content and microbial activity obtained by adition of sucrose and sucrose + urea. Spores of AMF were detected in sites with plant growth, only. Topsoil storage reduced organic carbon content, total nitrogen, spore number of AMF and microbial activity. In the material/substrates generated by iron mining, microbial activity responded only after carbon and nitrogen adition. Microbiological parameters evaluated were greater on the (undisturbed) forest site than on the other soils or substrates, indicating that the sites under reclamation were not under the same biological equilibrium. Soil microbiological evaluation could distinguish the degree of degradation or reclamation of the different sites studied.
microbial activity; mycorrhizal fungi; respiration; bacteria