AbstractObjectives of the study were to determine K rate and source optima for bromegrass (Bromus inermis Leyss.) and effect of treatments on uptake and balance of K and other nutrient elements. A 2‐year field study compared six rates of two K sources on bromegrass grown on a K‐deficient area. Dry matter yields were determined and the forage analyzed for N, P, K, Ca, Mg, AI, Ba, B, Fe, S, Sr, Cu, Zn, and Mn concentration.Each K rate increased K concentration of each cutting both years and decreased the Ca and Mg percentages. KCI increased K percentages, but had little effect on forage color, yield, or mineral uptake. Potassium sulfate increased both yields and mineral uptake. All K2SO4 rates eliminated the yellow foliage color. Each K increment of this K source increased the K and S percentages and uptake.Results indicate that both K and S deficiencies were present. Of the applied N, P, K, and S brome foliage removed 70 to 194%, 36 to 76%, 109 to 155%, and 19 to 95%, respectively.