Evaluating nitrogen management options for reducing nitrate leaching from northeast U.S. pastures

Area of Science:

• Environmental Science
• Agricultural Science
• Animal Science

Background:

• Intensively grazed pastures in the northeastern U.S. experience significant nitrate nitrogen (NO3-N) leaching due to high groundwater recharge.
• Nitrate leaching poses environmental risks to water quality.

Purpose of the Study:

• To evaluate management strategies for reducing NO3-N leaching in intensively grazed pastures.
• To assess the efficacy of energy supplementation and white clover use in mitigating nitrogen loss.

Main Methods:

• Utilized the Cornell Net Carbohydrate and Protein System Model.
• Employed a recently developed nitrogen leaching index.
• Simulated various management options for grazing dairy cows.

Main Results:

• Energy supplementation improved nitrogen efficiency in cows but did not guarantee reduced NO3-N leaching at the pasture scale without stocking rate control.
• Incorporating white clover decreased NO3-N leaching but resulted in lower dry matter yield and reduced stocking rates.
• Economic analysis indicated substantial economic benefits from energy supplementation options at current prices.

Conclusions:

• Management strategies like energy supplementation and white clover have varying impacts on NO3-N leaching and pasture productivity.
• Economic viability of NO3-N reduction strategies depends on milk prices and nitrogen costs.
• Controlling stocking rate is crucial for effective NO3-N leaching reduction with energy supplementation.