This study was conducted to ascertain the percent of available K, Cl, and SO4‐S recovered by alfalfa (MedicagosativaL. cv. ‘Vernal') herbage when various rates of K as KCl and K2SO4were topdressed and also to determine where residual K, Cl, and SO4‐S accumulated in the soil profile. An established stand of alfalfa growing on low fertility silt loam soil was topdressed in the spring of each of two harvest years with 0, 448, 896, 1344, and 1792 kg/ha of K as KCl or K2SO4. Four harvests were taken during each harvest year (1972 and 1973). Soil samples were taken during the autumn of 1973 to a depth of 91.4 cm in KCl‐fertilized plots, and to a depth of 76.2 cm in K2SO4‐fertilized and control plots.