Diurnality of soil nitrous oxide (N2O) emissions

I. Gelfand, R. Moyer, A. Poe, D. Pan, M. Abraha, J. Chen, M. A. Zondlo, P. Robertson

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Soil emissions of nitrous oxide (N2O) are important contributors to the greenhouse gas balance of the atmosphere. Agricultural soils contribute~65% of anthropogenic N2O emissions. Understanding temporal and spatial variability of N2O emissions from agricultural soils is vital for closure of the global N2O budget and the development of mitigation opportunities. Recent studies have observed higher N2O fluxes during the day and lower at night. Understanding the mechanisms of such diurnality may have important consequences for our understanding of the N cycle. Wetested the hypothesis that diurnal cycles are driven by root carbon exudes that stimulate denitrification and therefore N2O production. Alternatively, we considered that the cycle could result from higher afternoon temperatures that accelerate soil microbial activity. Were moved all plants from a corn field plot and left another plotuntouched. We measured soil N2O emissions in each plot using a standard static chamber technique throughout the corn growing season. And also compared static chamber results to ecosystem level N2O emissions asmeasured by eddy covariance tower equipped with an open-path N2O sensor. We also measured soil and air temperatures and soil water and inorganic N contents. Soil N2O emissions followed soil inorganic N concentration sand in control plot chambers ranged from 10 μg N m-2 hr-1 before fertilization to 13×103 after fertilization. We found strong diurnal cycles measured by both techniques with emissions low during night and morning hours and high during the afternoon. Corn removal had no effect on diurnality, but had a strong effect on the magnitude of soil N2O emissions. Soil temperature exhibited a weak correlation with soil N2O emissions and could not explain diurnal patterns. Further studies are underway to explore additional mechanisms that might contribute to this potentially important phenomena.
Original languageEnglish GB
Title of host publicationAmerican Geophysical Union, Fall Meeting 2015
StatePublished - 1 Dec 2015
Externally publishedYes


  • 0315 Biosphere/atmosphere interactions
  • 0414 Biogeochemical cycles
  • processes
  • and modeling
  • 0469 Nitrogen cycling
  • 0490 Trace gases


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