[en] Potassium (K) and radiocaesium (RCs) were chemically extracted from soils derived from granite (G soils) and sedimentary rock (S soils) in Fukushima, Japan. The extractants employed were 1 M HNO₃, concentrated HNO₃, and HF + HClO₄. As S soils contain a lower amount of trioctahedral 2:1 phyllosilicates than G soils, the RCs/K ratio was higher in S soils than in G soils with 1 M HNO₃ extraction, indicating that the potential risk of soil-to-plant transfer of RCs is higher in S soils than in G soils. In conclusion, information about surface geology is important in predicting the spatial pattern of soil characteristics related to transferability of RCs. (author)