Location: Soil and Water Management ResearchTitle: Capture efficiency of four chamber designs for measuring ammonia emissions
|ALEXANDER, JON - University Of Minnesota|
|SPACKMAN, JARED - University Of Idaho|
|WILSON, MELISSA - University Of Minnesota|
|FERNANDEZ, FABIAN - University Of Minnesota|
|Venterea, Rodney - Rod|
Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2021
Publication Date: 8/4/2021
Citation: Alexander, J., Spackman, J., Wilson, M., Fernandez, F., Venterea, R.T. 2021. Capture efficiency of four chamber designs for measuring ammonia emissions. Agrosystems, Geosciences & Environment. 4(3). Article e20199. https://doi.org/10.1002/agg2.20199.
Interpretive Summary: Emissions of ammonia gas from cropped soils represent an economically significant pathway by which fertilizer nitrogen can be lost from the soil-crop system. Also, once emitted to the atmosphere, ammonia can promote the formation of small particles that affect air quality or be deposited downwind and impact ecosystem function. Chambers are a commonly used method to quantify ammonia emissions in plot-scale agricultural research, but there is wide variation in the design and efficiency of chambers. This study compared four different chamber designs, open, open + membrane, semi-open, and closed. Each chamber type was deployed over a dilute ammonia solution for six hours on four dates to determine capture efficiencies. The open design had the greatest capture efficiency relative to the estimated total emissions, while the semi-open chamber was least efficient. The closed chamber reduced emissions by inhibiting gas movement beneath the chamber. These results will be useful for researchers assessing improved measurement methods to accurately quantify ammonia emissions.
Technical Abstract: Chambers are a commonly used method to quantify NH3 emissions in plot-scale agricultural research. While this method is widely used, its accuracy may be influenced by the overall design of the chamber, its components, and its interaction with the environment. Four NH3 chamber designs, including open, open + PTFE, semi-open, and closed, were deployed over a dilute NH3 solution for six hours on four dates to determine the effect of chamber design on NH3 capture efficiency. The solution volume and concentration were measured before and after acid trap deployment and total volatile NH3 emission was assumed to be equal to the mass N loss. The NH3 capture efficiency relative to the estimated total emissions was greatest for the open design (12.9%), while the semi-open chamber was the least efficient (3.5%). The closed chamber reduced NH3 emissions relative to the open and semi-open designs by inhibiting convective gas transport beneath the chamber footprint.