Nitrous Oxide Emissions From Cover Crop Systems in the US Midwest Under Conventional and Organic Management.

N₂O is the largest contributor to the GHG burden of cropping systems in the US, with emissions primarily due to N fertilizer inputs and other soil management activities. The practice of including winter cover crops in corn-based row-crop systems is not widely adopted but rising, with cereal grains, legumes, forage grasses and Brassicas planted.

The beneficial impacts of cover crops on agro-ecosystem functioning that include reduced soil erosion, increased SOM, and weed suppression are well known. However, no studies have investigated the effect of cover crops and their residue quality (e.g., C:N ratio, lignin content) on N₂O emissions in systems with multiple cover crop species under Conventional and Certified Organic management. Quantifying N₂O emissions under varying management is important for improving the accuracy of inventories of agricultural GHG emissions, evaluating their potential as a GHG mitigation strategy and will help evaluate the potential of new market based incentives such as carbon credits to help farmers transition to organic certification.

Here we present N₂O emissions from a corn-soybean-winter wheat rotation with varying cover crops (Annual Ryegrass, Oilseed Radish, Red Clover) under Conventional and Certified Organic management at the Kellogg Biological Station in SW Michigan. The impacts of variation of N fertilizer formulation, tillage, cover crop type, and termination practice within and between the systems sites will be presented.