288-7 Nitrous Oxide Fluxes Measured by Micrometeorological Techniques in a Barley Crop.



Tuesday, October 18, 2011: 9:35 AM
Henry Gonzalez Convention Center, Room 210A, Concourse Level

Andrew C. VanderZaag1, Claudia Wagner-Riddle2, Adriana Furon2 and Rob Gordon2, (1)Agriculture and Agri-Food Canada, Ottawa, ON, Canada
(2)School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
Uncertainty about nitrous oxide (N2O) emission factors remains high and there is a need for more data. In particular, large emission events during spring thaw and after fertilisation contribute greatly to the annual total. Characterising the effect of management practices on N2O emissions is also desirable, which requires measurements on multiple plots.

Much of the data on N2O emissions come from chamber methods, which have advantages but nevertheless disturb the surface environment and are physically difficult to implement at times. Micrometeorological methods have the advantage of not disturbing the surface. Two micrometeorological techniques for measuring N2O emissions are flux-gradient and eddy covariance. The flux-gradient technique is convenient for measuring N2O flux continuously and simultaneously from multiple large plots using a single analyser. However, the technique relies on assumptions about the relationship between vertical gradients and fluxes. Eddy covariance, in contrast, has a robust theoretical basis and requires fewer assumptions. However, it requires the N2O sensor to be located near the measurement tower, limiting measurements to a single plot per analyzer.

In this work we measured N2O flux from winter barley in Ontario, Canada, during spring thaw and after nitrogen fertilisation. Gradient and eddy covariance approaches were used simultaneously with two tunable diode lasers. Fluxes from each method are presented and discussed.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Agriculture, Emissions, and Air Quality