The study compared the yields of a grass called Chloris gayana grown alone versus mixed with a legume called Stylosanthes gracilis in Uganda. The grass/legume mixture gave twice the yield of pure grass, and when fertilized with phosphorus and sulfur, the mixed pasture produced over 3 times as much as the pure grass. The legume in the mixture competed with the grass, reducing its growth. Nitrogen increased grass growth but had no overall effect on total production in the grass/legume mix. The biggest fertilizer effect was sulfur on the legume.