|Delahoy, James - PENN STATE UNIVERSITY|
|Muller, Lawrence - PENN STATE UNIVERSITY|
Submitted to: The Scientific World
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 2001
Publication Date: November 20, 2001
Citation: Stout, W.L., Delahoy, J.E., Muller, L.D., Saporito, L.S. 2001. Evaluating nitrogen options for reducing nitrate leaching from northeast u.s. pastures. The Scientific World. 1(s2):887-891. Interpretive Summary: Management options for controlling nitrate nitrogen leaching from intensively grazed pasture in the northeast USA were evaluated using computer models. It was found that controlling stocking rate reduced nitrate nitrogen leaching, but milk production would be reduced. Energy supplementation increased nitrogen use efficiency within the animal, but did not necessarily decrease nitrate leaching. Economic benefits of reducing nitrate nitrogen with either option must be evaluated in light of current milk prices and fertilizer nitrogen costs.
Technical Abstract: Substantial amounts of nitrate nitrogen can leach from intensively grazed pasture in the Northeast U.S., where there is about 30 cm of groundwater recharge annually. Management options for reducing nitrate nitrogen leaching were evaluated for this environment using the Cornell Net Carbohydrate and Protein System Model and a recently developed nitrogen leaching index. Management options utilizing energy supplementation of grazing dairy cows could improve nitrogen efficiency within the cow, but would not necessarily reduce nitrate nitrogen leaching at the pasture scale if stocking rate was not controlled. The management option of using white clover to supply nitrogen to the pasture decreased nitrate nitrogen leaching, but produced less dry matter yield, which in turn reduced stocking rate. The economic returns of reducing nitrate nitrogen with these options need to be evaluated in light of milk prices and commodity and fertilizer nitrogen costs. At current prices and costs, the economic benefit from the energy supplementation options is substantial.