Reducing Agricultural Emissions

Problem

How can growers help to reduce potent greenhouse gas (GHG) emissions that may result from organic agriculture practices?

• Organic agriculture relies on microbial cycling of nutrient inputs from legume cover crops and applications of animal manure, a combination of practices that can curtail nutrient runoff and soil erosion but at the same time release nitrous oxide.
• Nitrous oxide is a greenhouse gas that is about 300 times better at trapping heat than carbon dioxide.

Findings

Researchers measured soil nitrous oxide emissions for two growing seasons in four corn-soybean-winter grain rotations, with tillage, cover crop, and manure-management variations typical of North American organic agriculture.

• They found a significant "leak" from the combination of nitrogen inputs from the cover crops and the manure prior to corn planting due to the soil's inability to hold nitrous oxide and convert it to harmless nitrogen before escaping to the atmosphere.

Impact

As a result of their findings, the researchers proposed several strategies to reduce those unintended consequences, including removing a fraction of the cover crop's aboveground biomass before corn planting. By preventing the co-location of fresh biomass and manure they decreased nitrous oxide emissions by 60 percent.

Research Credit

Team

• Debasish Saha, Jason Kaye, Arnab Bhowmik, Mary Ann Bruns, John Wallace, Armen Kemanian

Participating Departments

• Ecosystem Science and Management
• Plant Science

Competitive Funding

• USDA NIFA (Organic Transitions)
• USDA NIFA (AFRI)

Federal and State Appropriations

• USDA NIFA Hatch Project PEN04571, Accession #1003346

Emerging Discoveries

Nitrous oxide emissions, coming from legume cover crops, manure, can be reduced

August 02, 2021

The application of manure after the growth and demise of legume cover crops in rotations is a recipe to increase nitrous oxide releases during ensuing corn growth, according to a team of Penn State researchers who conducted a new study. They suggest that innovative management strategies are needed to reduce these emissions.

Published Research

Organic fertility inputs synergistically increase denitrification-derived nitrous oxide emissions in agroecosystems

• Saha, D., Kaye, J. P., Bhowmik, A., Bruns, M. A., Wallace, J. M., & Kemanian, A. R. (2021). Organic fertility inputs synergistically increase denitrification-derived nitrous oxide emissions in agroecosystems. Ecological Applications, 31(7), [e02403]. https://doi.org/10.1002/eap.2403