Combined application of calcium carbonate and NPKS fertilizer improves early-stage growth of poplar in acid soils

•The combined effects of calcium carbonate and NPKS fertilizer addition on growth of Populus spp. were assessed based on the results from a field and a pot experiment.•The fertilization effect on poplar growth was strong only if soil conditions in terms of pH and exchangeable Ca were at a sufficiently high level.•Available nutrient concentrations in the soil and foliar nutrient concentrations in the plant suggested co-limitation of poplar growth by N and Ca.•The results of this study emphasize the importance of adapting the level of CaCO3 to the given soil conditions.