Verification techniques for N2O emission at the paddock scale in New Zealand: FarmGas2006
Mike Harvey A E , Elizabeth Pattey B , Surinder Saggar C , Tony Bromley A , Dave Dow B , Michael Kotkamp D , Ross Martin A , Rowena Moss A and Jagrati Singh CA National Institute for Water and Atmospheric Research, Wellington, New Zealand.
B Agriculture and Agri-Food Canada, Ottawa, Canada.
C Landcare Research Ltd, Palmerston North, New Zealand.
D National Institute for Water and Atmospheric Research, Lauder, New Zealand.
E Corresponding author. Email: m.harvey@niwa.co.nz
Australian Journal of Experimental Agriculture 48(2) 138-141 https://doi.org/10.1071/EA07243
Submitted: 6 August 2007 Accepted: 1 November 2007 Published: 2 January 2008
Abstract
High-precision micrometeorological measurement with tunable diode laser (TDL)-based trace gas analysers provides a continuous spatially integrating and non-intrusive measurement technique that is capable of detecting and quantifying episodic N2O emission at the paddock scale. Results are presented from the FarmGas2006 measurement campaign conducted on a commercial dairy farm in North Canterbury, New Zealand, over 3 weeks in October 2006. This was the first field deployment of a TDL instrument for paddock-based N2O flux measurement in New Zealand. A goal of this campaign was assessment of a range of atmospheric N2O sensing technologies and micrometeorological approaches. In this paper the capabilities of TDL technology are compared with gas chromatography (GC) in flux-gradient measurements. Baseline emission was <100 ng N/m2.s and increased to <250 ng N/m2.s following grazing by the dairy herd. There was very good correlation between GC- and TDL-determined fluxes and also good agreement between the instruments in the mean emission in 10 days before (45–50 ng N/m2.s) and after (75–80 ng N/m2.s) paddock grazing. The flux was characterised by events of high emission lasting several hours such that half of the total N2O was emitted in ~10% of the time over the duration of the campaign. We discuss the implications of this and advantages of high-precision techniques as tools for ‘top-down’ verification and for the assessment of N2O emission mitigation options.
Acknowledgements
The FarmGas2006 campaign was funded by through MRST CRI Capability Fund contract ‘New technologies for on-farm greenhouse gas emission assessment and mitigation studies’, and the Foundation for Research Science and Technology Public Good Science Fund under contracts CO9X0212 ‘Reducing Greenhouse Gas Emissions from the terrestrial biosphere’, Landcare Research and CO1X0204 ‘Drivers and Mitigation of Global Change’, NIWA. Field work was made possible through the kind support of the owners and management of Medcroft Dairy Farm.
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