A mesocosm experiment was set up to investigate how maize responds to the application of basalt, concrete fines, and steel slag, using a dose–response approach. Biomass increased with basalt application but did not change with concrete fines or steel slag, except for increased tassel biomass. Mg, Ca, and Si generally increased in the crops, whereas toxic trace elements remained unaffected or even decreased in the plants. Overall, crops were positively affected by the application of silicate materials.