Field studies were conducted for three years in North Alabama on a Dewey silt loam (Typic Paleudults) to determine K fertilizer rates and application time for cotton (Gossypium hirsutum L.) following alfalfa (Medicago saliva L.). The site selected had been in alfalfa production for 5 years. Potassium was applied to cotton at rates ranging from 0 to 180 lbs K2O ac-1. The fertilizer was broadcast in the spring or split applied in the fall and spring. Treatments included two cotton varieties: 1) Deltapine 50 and 2) Stoneville 825. The experiment was a split-plot design and varieties were the whole plots. During the first year of the study (1987) seed cotton yields were not affected by any treatment. In the second year of the,study (1988) annual applications of 60 lbs K2O ac-1 in the spring increased seed cotton yields 192 lbs ac-1. The greatest response was obtained during the third year of the study (1989). In 1989, seed cotton yields were increased 872 lbs ac-1 by applying 60 lbs K2O ac-1 in the spring. Results from the study show that rates above 60 lbs ac-1 did not result in further yield increases. Split and timing of application did not affect yields. Differences between the two varieties were inconsistent. Mehlich I extractable K was increased by the application of K and an average of 5.8 lbs K2O as needed to increase the soil test K by 1 lb ac-1. The results from this study suggest that multiple annual applications of K may be needed to maximize cotton yields when following alfalfa.