Responses to potassium (K) by potted Sorghum (Sorghum bicolor) were determined in soils taken from four Local Government Areas in Kwara State and regressed with K extracted with five laboratory methods. Results showed that without K application, dry-matter yields were relatively high and responses to 15 kg, 30 kg and 60 kg K ha-1 were negative and not significant in the soils derived from basement complex and sandstones. When dry matter yields without K application were less than 9.00 g/pot, there were no significant responses to K application and responses were significant only when they were more than 9%. Potassium extracted with N NH4OAc pH 7.0 gave the best indication of dry matter yields when K was not applied, with the equation, Y = 0.005X + 3.1902, r = 0.1622. Significant responses were obtained in soil testing with less than 15 kg K ha-1 with this method. Furthermore, K extracted with hot N HNO3 was almost equal with a higher value in virtually all soils to exchangeable K extracted with N NH4OAc and could be used in place of this extractant as it also accounts for the replenishable form of K in soil.