High rates of N and P fertilizers and manure changed the botanical composition and increased hay yields from native flood meadows. Rush and sedge composed 62, 54, 12, and 4% of the hay at 0, 200, 400, and 600 lb. N/acre, while grasses composed 20, 44, 88, and 96% with the same rates of N. Yields of hay were significantly increased with N, P, and manure. The treatments had little effect on the crude-protein content in the hay. Increasing rates of N decreased the P content in the forage.