Ammonia flux measurements above a corn canopy using relaxed eddy accumulation and a flux gradient system

Andrew J. Nelson, Nebila Lichiheb, Sotiria Koloutsou-Vakakis, Mark J Rood, Mark Heuer, La Toya Myles, Eva Joo, Jesse Miller, Carl Bernacchi

Research output: Contribution to journalArticle

Abstract

Studies of NH3 flux over agricultural ecosystems in the USA are limited by low temporal resolution (typically hours or days) and sparse spatial coverage, with no studies over corn in the Midwest USA. We report on NH3 flux measurements over a corn canopy in Central Illinois, USA, using the relaxed eddy accumulation (REA) and flux gradient (FG) methods, providing measurements at 4 h and 0.5 h intervals, respectively. The REA and FG systems were operated for the duration of the 2014 corn-growing season. Flux-footprint analysis was used to select data from both systems, resulting in 82 concurrent measurements. Mean NH3 flux of concurrent measurements was 205 ± 300 ng m−2 s−1 from REA and 110 ± 256 ng m−2 s−1 from FG for all concurrent samples. Results from both methods were not significantly different at a 95% confidence level for all concurrent measurements. The FG system resolved NH3 emission peaks at 0.5 h averaging time that were otherwise un-observed with 4 h REA averaging. Two early-season peak emission periods were identified (DOY 130-132 and 140-143), where the timing and intensity of such emissions were attributed to a combination of urease inhibitor, applied as a field-management decision, and localized soil temperature and precipitation. Given the dependence of NH3 fluxes on multiple parameters, this study further highlights the need for increased spatial coverage and high temporal resolution (e.g., <1 h) of measurements to better understand the impact of agricultural NH3 emissions on air quality and the global nitrogen cycle. Such measurements are also needed for evaluation of models describing surface-atmosphere exchange of NH3.

LanguageEnglish (US)
Pages104-113
Number of pages10
JournalAgricultural and Forest Meteorology
Volume264
DOIs
StatePublished - Jan 15 2019

Fingerprint

flux measurement
eddy
ammonia
maize
canopy
corn
agricultural emission
nitrogen cycle
agricultural ecosystem
footprint
soil temperature
inhibitor
air quality
growing season
urease inhibitors
emissions factor
atmosphere
agroecosystems
duration
method

Keywords

  • Ammonia
  • Bi-directional flux
  • Corn
  • Flux gradient
  • Relaxed eddy accumulation
  • Urease inhibitor

ASJC Scopus subject areas

  • Forestry
  • Global and Planetary Change
  • Agronomy and Crop Science
  • Atmospheric Science

Cite this

Ammonia flux measurements above a corn canopy using relaxed eddy accumulation and a flux gradient system. / Nelson, Andrew J.; Lichiheb, Nebila; Koloutsou-Vakakis, Sotiria; Rood, Mark J; Heuer, Mark; Myles, La Toya; Joo, Eva; Miller, Jesse; Bernacchi, Carl.

In: Agricultural and Forest Meteorology, Vol. 264, 15.01.2019, p. 104-113.

Research output: Contribution to journalArticle

Nelson, Andrew J. ; Lichiheb, Nebila ; Koloutsou-Vakakis, Sotiria ; Rood, Mark J ; Heuer, Mark ; Myles, La Toya ; Joo, Eva ; Miller, Jesse ; Bernacchi, Carl. / Ammonia flux measurements above a corn canopy using relaxed eddy accumulation and a flux gradient system. In: Agricultural and Forest Meteorology. 2019 ; Vol. 264. pp. 104-113.
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