High rates of potassium (K) are often applied in an attempt to increase stress tolerance of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] turfs. Two field-grown bermudagrass cultivars, `Tifdwarf' and `Tifway', were used to determine the influence of applied K on plant nutrient content and nutrient retention in two soils. Six rates of K ranging from 0 to 390 kg·ha-1 were applied twice per month each growing season from 1992 to 1994. The cultivars were established on both a sand-peat (9:1 by volume) and loamy sand. Potassium chloride and K2SO4 were compared as sources of K, and were applied simultaneously with N applications. Extractable soil K and leaf tissue K concentrations increased with increasing K rates. There was a critical K fertilization level (74 to 84 kg·ha-1) for each cultivar and medium combination beyond which no increase in tissue concentration was observed. Increasing K fertilization resulted in a decrease in extractable Ca and Mg in both media with corresponding decreases in tissue Ca and Mg concentrations. High K rates appear to increase the potential for Ca and Mg deficiencies in bermudagrass, indicating that rates higher than those that provide sufficient K levels for normal growth should not be used.