We ascertained the relationship between the zonal pattern and the pasture vegetation of a volcanic soil polluted with dust from a cement factory after 70 years of operation, with parameters linked to soil microbial activity (soil basal respiration and hydrolases) and physical–chemical properties. Six sampling zones were established at distances of 1, 2, 3, 4, 5 and 6 km away from the cement plant, considering the latter one as the zone where the pastures were unaffected by the cement dust. Plant cover was negatively affected by cement dust, showing a sharp decline with decreasing distance to the cement factory. The values of pH and extractable K were two units and 2·3‐fold higher, respectively, in the sampling zone nearest to the factory, in comparison with those in the unaffected zone. The levels of total Cr, Pb, Ni and Cd were normal and did not vary significantly with distance to the cement factory. Soil respiration and the protease, phosphomonoesterase and β‐glucosidase activities declined significantly with decreasing distance to the cement factory. Urease activity was only decreased in the zone nearest to the factory, in comparison with that in the unaffected zone. The soil respiration and hydrolase activities were correlated positively with soil organic matter and plant cover and negatively with soil pH and extractable K concentration. The prolonged exposure to cement dust has resulted in shifts in the soil microbial function, which follows a spatial pattern related to soil alkalization and the decrease in pasture production. Copyright © 2016 John Wiley & Sons, Ltd.