Basalt rocks are one of the most common parent materials of large areas of soil in southern Brazil. Several major plant nutrients are present in its composition. The objective of this study was to evaluate the effect of the addition of increased rates of ground basalt rock on the nutrient availability of soil, during three periods of incubation. The rocks tested were a microcrystalline and an olivine-basalt. The rates of basalt rock, corresponding to 0, 5, 10, 25, 50 e 100 t ha-1, basalt were incubated in a Dark Red Latosol and a Red Yellow Podzolic soil. The experiment was carried out under greenhouse conditions at the Agronomy School of Federal University of Rio Grande do Sul. After 30, 150 and 300 days of incubation, the contents of K, Ca, Mg, pH, H + Al, P and CEC of the incubated soils were determined. The different rates tested caused an increase in these variables. However, the increases observed were small, except for P, the value of which may have been overestimated by the extractor used. The release of these elements to the soil varied with incubation period, but not with rock type, with the exception of the concentrations of Ca and P, which were higher for the olivine-basalt. The small release of nutrients from the rocks indicates that these materials cannot be used as the major source of plant nutrients.
powdered basalt; soil characteristics; and fertilizers