Slags, consisting of calcium silicate, are an alternative for the correction of Ca and Mg requirements in soils. This study was done at Fazenda Floresta do Lobo - Uberalndia-MG, to evaluate the effect of slag application as a source of Si, Ca and Mg for the growth of eucalypt in comparison to lime. The experiment was done in a typical dystrophic red latosol, on November 30 2005, in a completely randomized design, as a 5x2 factorial to compare two sources of soil correctives in five doses, with five replications. The treatments of slag and lime were applied in the proportion of 0, 1/4, 1/2 1 (1.5 t ha(-1)) and 2 time the corrective requirement. Slag supplied more Si than lime, showing a linear response. In contrast, magnesium was supplied in greater amounts by dolomitic lime. No differences were found for Ca contents and the DBH (diameter at breast height) between the two sources, and both of them had linear responses. It can be concluded that the correctives increased the contents of Ca, Mg and the DBH.