Wednesday, November 7, 2007 - 3:15 PM
291-7

Reducing Nitrous Oxide (N2O) Gas Emissions in Agricultural Crop Production.

Neville Millar1, G. Philip Robertson1, Peter G. Grace2, David Rowlings2, and Andrew T. Corbin1. (1) Michigan State University Kellogg Biological Station, Michigan State University - KBS, 3700 E. Gull Lake Drive, Hickory Corners, MI 49060, (2) Institute for Sustainable Resources, Queensland University of Technology, Brisbane QLD 4001, Australia

Nitrous oxide is a significant contributor to global climate change, with each ton emitted into the atmosphere equivalent in terms of global warming potential to 296 tons of CO2 emissions. Nitrous oxide is emitted from cultivated soils, animal wastes and biomass burning, with agricultural activities responsible for 65-80% of total global fluxes. Soil nitrogen (N) availability is the best predictor of soil N2O flux, with total N inputs used to estimate soil N2O contributions to national gas inventories. Increasing crop N use efficiency by altering N management practices is likely to be the most promising strategy for large scale mitigation of N2O production from agriculture.

Previous research at Kellogg Biological Station shows a non-linear response of N2O flux to N-fertilizer inputs, with similar crop yields following both modest and high N fertilizer application, but with much greater N2O fluxes from high N fertilizer application. This suggests great potential for management of N2O fluxes by altering N inputs – a modest reduction in N-fertilizer application may result in little or no crop yield reduction, but have a major impact on reducing N2O fluxes. New research at KBS in 2007 will further investigate these findings.

Field experiments have been set up to provide data for comparison of N2O fluxes (automated chamber methodology) with multiple fertilizer-N rates (0, 34, 67, 134, 168 and 246 kg N ha-1) soil N, moisture and temperature, and crop yield. Results from this first season will be presented, along with progress on the development of quantitative regional and national models to predict relationships between N2O flux, crop yield and soil / climate regimes. Identification of factors that may lead to farmer acceptance of new fertilizer-N management strategies resulting from this research and the potential of these practices as greenhouse gas offset options will also be discussed.


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