For two soil types, loamy degraded chernozem and silty loam, the conversion equations for phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) determined after extraction with Mehlich 1‐, 2‐, and 3‐, and CaCl2‐extractants, for K after extraction according to Schachtschabel‐, and P according to Egner‐, Bray‐, and Olsen‐methods were found out. The results show that for most nutrients, it is possible to use for data‐conversion 1st order equation common for both soil types. For some nutrients and extractions methods, different conversion equations seem to be necessary. Close correlations between organic matter and total carbon (C) (r = 0.929***) and hydrogen (H) (r = 0.912***) and between total C and H (r = 0.857***) were also confirmed. Very close relations were found for pH determined in CaCl2‐ and KCl‐extracts (r = 0.991***). For both soil types, similar curves of relations of soil pH as the functions of Ca‐content (according to Mehlich 1‐, 2‐, and 3‐methods) with typical tendency to saturation were observed. Effects of K, Ca, Mg, pH, and soil organic matter on Mehlich 1‐, 3‐, and CaCl2‐extractable P were studied too.