AbstractInteracting effects of phosphorus, potassium and sodium on the growth and nutrient uptake inStylosanthes fruticosawere studied in its native sandy soil and solution culture. High phosphorus in the medium had adverse effects on growth. High potassium level completely masked or lessened adverse effects of high phosphorus. High sodium level adversely affected growth only in combination with high phosphorus and low potassium. Shoot nutrient content data indicated that phosphorusper semay not inhibit growth. Selective uptake of potassium against sodium was eliminated by high phosphorus. It is suggested that high concentration of phosphorus in the medium effects membrane permeability and the effect of phosphorus on plant growth is primarily through its influence on uptake of other ions.