Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2000
Publication Date: N/A
Interpretive Summary: Animal wastes from chickens and pigs are often applied to pastures and hayfields in the southeastern U.S. Nutrients in these animal wastes, such as nitrogen and phosphorus, are often applied in amounts greater than plant needs and buildup within the soil occurs. Hay production and sale of hay off-farm could help remove these excess nutrients from the soil. Our research seeks to maximize nutrient uptake in forage crops to help remove excess nutrients such as nitrogen, phosphorus, potassium, copper, and zinc from the field. The correct choice of forage species is important. Forages vary in concentration and amount of nutrients retained in the plant. Forage stems contain the greatest amount of the plant's nitrogen, phosphorous, potassium, copper, and zinc so forages with upright stems should be grown to maximize nutrient removal. Forages with runners that grow along the ground, such as bermudagrass, should be managed to minimize runner formation and maximize forage that can be harvested to obtain the greatest nutrient removal. Cultivars differ in nutrient uptake through the differences seen among cultivars so far have not been great. Forages should be harvested at full maturity to maximize dry matter yield and achieve maximum nutrient uptake.
Technical Abstract: Animal wastes, such as poultry litter and swine effluent, are often applied to pastures and hay fields in the southeastern U.S. Our research aims to maximize uptake of nutrients in forages grown for hay to facilitate removal of excess nutrients from these fields. Selection of proper forage species is important in maximizing nutrient removal since forages differ in concentration and uptake of major nutrients (N, P, K) and metals (Cu, Zn). Different management practices are required to maximize nutrient uptake depending on where within the plant the nutrients of main interest are located. For example, a majority of P in forages is located in stems and runners. For maximum P removal in upright forages such as annual ryegrass, Lolium multiflorum Lam., management practices should maximize stem production. In species with prostrate runners such as bermudagrass, Cynodon dactylon (L.) Pers., runner formation should be minimized since prostrate runners will not be harvested for hay. Cultivars can differ in nutrient uptake and removal, though the differences we have observed so far have not been great. Nutrient concentration in forages decreases with maturity, but nutrient uptake increases to full maturity. Forages should be harvested at full maturity to maximize dry matter production and nutrient uptake.