Effect of Cover Crops On Nitrous Oxide Emissions, Nitrogen Availability and Carbon Accumulation in Organic Versus Conventionally Managed Systems.

Few studies have investigated the effect of cover crops on N mineralization-immobilization patterns. None have looked simultaneously at long-term N₂O emissions in field systems with cover crop species under conventional and certified organic management.

Here we describe a study investigating the effects of various cover crop species (annual ryegrass, oilseed radish, and red clover), specifically their residue quality and termination time on N₂O emissions, N availability patterns, and C accumulation in a corn-soybean-winter wheat rotation under conventional and certified organic management at two independent sites at the Kellogg Biological Station in SW Michigan. Our hypothesis is that cover crop use in organic and conventional systems can improve N synchrony, decrease N₂O emissions, and better sequester C compared to non-cover crop systems. Major goals of this work are to increase farmer knowledge of cover crop use in relation to N use efficiency and GHG mitigation, improve the accuracy of inventories of agricultural N₂O emissions in the US, and evaluate the economic potential of new market based incentives such as carbon credits to help farmers transition to organic certification.

We will present details of experimental design, field management practices, gas sampling methodologies, and residue analysis as well as preliminary data from the first growing season.