Application of Cavity-ring Down Spectroscopy to Quantify NH3 Fluxes from Fertilizer Application in the Midwestern U.S.

Tuesday, 16 December 2014
Jason Anthony Caldwell1, Daryl Sibble1, Mark Heuer2, Elijah Johnson1, Mark J Rood3, Sotiria Koloutsou-Vakakis4 and LaToya Myles5, (1)Florida Agricultural and Mechanical University, Tallahassee, FL, United States, (2)NOAA/ATDD, Oak Ridge, TN, United States, (3)University of Illinois, Urbana, IL, United States, (4)Univ of IL--Civil & Envir Engr, Urbana, IL, United States, (5)NOAA Oak Ridge, Oak Ridge, TN, United States
Ammonia (NH3) emissions from managed agriculture in the Midwestern region of the U.S. contribute to increased levels of particulate matter in the atmosphere and detrimental ecological changes. To better understand the exchange of ammonia between the atmosphere and biosphere and identify the drivers of these processes, measurements of NH3 flux were conducted over a 200 m2 fertilized maize field in Illinois. A flux-gradient system paired with a cavity-ring down spectrometer measured fluxes from pre-cultivation through senescence of the crop. The use of a custom automated exchange mechanism allowed for continuous sampling, both above-canopy and in-canopy. Results indicated diurnal cycling of NH3 with higher concentrations in the early afternoon, although the pattern was not consistent. As expected, fertilization of the field at planting produced a marked increase in NH3 emission from the field.