Developing climate-friendly farming practices to reduce nitrous oxide emissions

Nitrous oxide is a greenhouse gas that is about 300 times better at trapping heat than carbon dioxide, so even small emissions of nitrous oxide affect the climate. Organic agricultural practices, such as legume cover crops and applications of animal manure, can curtail nutrient runoff and soil erosion when combined but at the same time release nitrous oxide.

Researchers at Pennsylvania State University are addressing this leak by identifying nitrous oxide-production pathways and mitigation opportunities. They measured emissions over two growing seasons in four corn-soybean-winter grain rotations with tillage, cover crop and manure-management variations typical of North American organic agricultural practices.

The research identified key moments when nitrous oxide emissions significantly increased. For instance, nitrogen input from legume cover crops and manure prior to corn planting make the corn phase of three-year crop rotations the main source of nitrous oxide emissions. When preventing the co-location of fresh biomass and manure, the researchers found they could decrease the nitrous oxide emissions by 60%.

The findings from this research provide innovative management strategies that require no additional technologies or investments from growers. These recommendations can help producers to reduce unintended consequences presented by organic agricultural practices and provide readily adoptable pathways to mitigate the overall contributions to greenhouse gas emissions.

Project supported by USDA Competitive funds. Photo courtesy Pennsylvania Agricultural Experiment Station.