The response of Norway spruce seedlings to 157 samples of upper soil layers obtained from 66 forest sites with Norway spruce distributed throughout Switzerland was examined during a 4 months growth chamber study. The pH values of the soil samples ranged from 2.95 to 7.41, with 43% of the samples being acidic (pH<4.75) and with high concentrations of exchangeable Al. A comparison of two soil extraction methods, the NH₄Cl-extraction representing the `exchangeable' fraction of cations in soils and the NH<sub>4</sub>-acetate–EDTA-extraction representing the `extractable' (potentially plant available) fraction, revealed similar results only for the cation K. With the NH₄-acetate–EDTA-extraction, slightly more Al was extracted in nearly all the samples, and distinctly more Ca was extracted from samples with pH>6. Seedlings growing in these soil samples showed clear differences in biomass responses, when soils were arranged in classes according to the pH, the sum of `exchangeable' basic cations (BC), or the BC/Al molar ratio. Reduced biomass was observed at pH<4.75, at BC<100 mmol<sub>c</sub> kg<sup>−1</sup>, and at a BC/Al ratio <1. Additionally, a significant positive relationship occurred between root biomass and BC/Al ratio in soils with a low BC/Al ratio (<10), indicating a potential for the use of the BC/Al ratio of soil extracts to assess the risk of Al stress. In acidic soils, Ca concentrations in the shoots were reduced but Al concentrations were enhanced. This trend was also apparent when soils were arranged according the BC/Al ratio. Here, Ca concentrations in the shoots were steadily enhanced from BC/Al <1 to >1000, whereas Al was reduced. The Ca concentrations in the shoots were similar to the `exchangeable' amount of Ca in the soils, whereas for K and Mg an accumulation in the shoots occurred. The Al concentrations in the shoots, on the other hand, indicated a constant translocating rate of Al from the roots to the shoots independent of the `exchangeable' amounts of Al in the soils.