AbstractTo improve the quality of forest soils by applying basic rock powders tests were carried out in Vorarlberg (Austria) in 1987: in the vicinity of Möggers on Stagno‐Mollic Gleysol underAbieti‐Fagetum luzuletosum, in Nenzing on Calcaric Regosol and Cambisol underAbieti‐Fagetum luzuletosumand in Montafon on Stagno‐Dystric Gleysol underHomogyno‐Piceetum. The effects of a low dosage of rock powder application on nitrification, basal respiration, microbial biomass, xylanase, phosphatase and protease activities, the amount of nitrate nitrogen (NO3−‐N), and the soil pH were investigated. Additions of rock powder increased protease, NO3−‐N content and pH, but decreased phosphatase in the Ah‐horizon of the Stagno‐Mollic Gleysol. After 3 years the Ah‐horizon from the experimental site Nenzing showed statistically verified differences of all investigated parameters except xylanase. In the acid spruce forest soils of the Montafon site the rock powder had no statistically significant effect on microbiological parameters. Only the soil pH increased. It can be postulated that the application of rock powders furthered C‐ and N‐mineralization. In the long run this affects the turnover of mineral nu