Nineteen cultivated soil samples representing alluvial and nonallu­vial soils differing in clay and K content, were tested for K using the most conventional K-extraction procedures, namely: water soluble-K, ammonium acetate, nitric acid and 0/1 measurements. The results were compared and stati:,tically correlated with the EUF-K parameters de-sorbed from the soil samples. The relative yield of the actually uptake-K from those soils by clover plants in a pot experiment was measured, as a biological index, to evaluate the validity of both the EUF and the other methods in describing K status. The EUF-K parameters showed correla­tion with the most important conventional K extraction methods. The bi­ological test revealed that EUF-K parametrs are highly effective in de­scribing soil•K status, comparing with the other used methods. The results ascertained the suitability of the EUF method in order to easily characterizing the K availability status, providing information on K mobili­ty that cannot be obtained by the "static' conventional methods and for saving time and reagents.