For many years it has been suggested that the two major limiting factors to alfalfa (Medicago sativa) growth in the upper Midwest are soil pH and exchangeable soil potassium (Brown, 1928; Hull, 1934). Recent research reaffirms the benefits of raising pH to near neutral by adding lime to fields where alfalfa is to be grown in Wisconsin (Peters and Kelling, 1989; Peters and Kelling 1997). Potassium is removed from the soil by alfalfa in amounts greater than any other nutrient and there is substantial documentation of the benefits of adding supplemental potash to soils where alfalfa is to be raised (Attoe and Truog, 1950; Peterson et al., 1975; Smith and Powell, 1979; Erickson et al., 1981; Kelling, 1995). Research from Wisconsin has shown that potassium is required to enhance resistance to disease and lodging, and winter hardiness of alfalfa (Kelling, 1991; Schulte and Walsh, 1993). Additionally, potassium is involved in carbohydrate production and transport, enzymatic activity, and stomatal function in alfalfa (Munson, 1985). Potassium also balances the negative charges of organic and inorganic anions within the plant and may be involved in metabolic processes including the formation of starch and assimilation of nitrogen (Peters et al., 2000).