Nitrous Oxide Emissions from the Application of Fertilizers: Source Partitioning

Nitrous oxide (N₂O, a potent greenhouse gas (GHG)) emission reduction protocols are being developed by different entities with different interests, several of which rely only on reductions in N rate to achieve reduced N₂O emissions. A project was initiated in late 2011 to perform a meta-analysis of the peer reviewed published science to determine the effects of all four R’s (right source, rate, time, and place of application) on N₂O emissions in corn-soybean or continuous corn systems in North America, with a focus on the U.S.-states of Iowa and Illinois. More than 100 research papers have been assembled for potential inclusion of relevant parameters in the database; including presence and amount of irrigation, soil bulk density, water-filled pore space, and changes in soil organic carbon content or CO₂ emissions where available. The database will also include class variables for N timing (fall, spring, split, side-dress, etc.), placement (surface broadcast, incorporated, banded, etc.) and N source (urea, anhydrous ammonia, ammonium nitrate, urea ammonium nitrate, etc.). Completion of the database is expected by Spring 2012, and actual meta-analyses will follow.

This work helps support the TFI-led USDA Conservation Innovation Grants (CIG) demonstration project which aims to demonstrate that Midwestern corn-soybean producers can be incentivized to adopt new fertilizer management practices that will reduce N₂O emissions, increase crop productivity and nutrient use efficiency through BMP implementation, while also generating revenue from the monetization of carbon-based GHG credits. CA-32