Low-Power Gradient Approach to Measure N2O Fluxes.

Low-Power Gradient Approach to Measure N₂O fluxes

Benjamin G. Conrad, Steve Sargent, Claudia Wagner-Riddle and Shannon E. Brown

Traditional measurements of nitrous oxide (N₂O) emissions from agricultural soils have mostly relied on closed chambers and gas chromatography. With the development of fast response, high precision analyzers additional micrometeorological techniques to measure these emissions have been employed such as flux gradient (FG) and eddy covariance (EC).   These methods provide spatially integrated and high temporal resolution fluxes.  The TGA series of trace gas analyzers manufactured by Campbell Scientific, Inc. (Logan, USA) are based on tunable diode laser absorption spectroscopy and have been used in numerous studies to measure N₂O emissions from agricultural sites using the FG method. One limitation of these analyzers is the requirement of AC mains power to run the pump, electronics and heaters/fans. With recent engineering developments, a TGA100A was set up to measure N₂O emissions in FG mode with a new low power sample pump module giving a complete system power <30 W.   The system was deployed in a field study along-side a TGA200A, with heated vortex intake, measuring EC-N₂O fluxes over corn in Elora, Ontario. The noise of the N₂O measurement on the flux gradient TGA was quantified and compared to the N₂O noise of the EC TGA. Flux calculations from both systems and techniques were compared.