Fertilizer recommendations for forage hay production in Florida have been based on moderate yields and have not taken soil type into account. With increased concerns over mineral fertilizer costs and the potential for nutrient losses to the environment, the fertility requirements of some high-yielding subtropical forages were examined on a kandiudult, paleudult, and alaquod soil. Bermudagrass (Cynodon dactylon L.), bahiagrass (Paspalum notatum Flueggé), and perennial peanut (Arachis glabrata Benth.) were grown in 3 m x 6 m plots at three different locations and soils. Fertilizer was split applied at two different K (90 or 180 kg ha^-1), Mg (11 or 22 kg ha^-1), and S (22 or 44 kg ha^-1) concentrations. Grass forages were clipped every four weeks to a 7 cm height. Perennial peanut was clipped every eight weeks. Plant available (Mehlich III) P, K, Mg, and S were analyzed from 15 to 120 cm depth yearly. Treatment K and S fertilization was reflected in forage K and S concentrations for all plant species and soil types. However, forage responses were not readily observed with Mg fertilization. There was no yield response to fertilization practices for bahiagrass or perennial peanut during the first season. Bermudagrass grown on the alaquod (spodic) soil with supplemental K, Mg and S tended to have greater yields during the first season and had significantly greater yields during the second season. The alaquod soil had the lowest plant available S (< 20 mg kg^-1 in the upper 15 cm). Whereas the kandiudult had increasing plant available S with increasing soil depth (nearly 80 mg kg^-1 at 120 cm depth for bermudagrass). Supplemental S fertilization may improve high yielding bermudagrass production in some subtropical soils.