EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Determination of nitrous oxide processes in soil from depth profiles of natural abundance stable isotope values by diffusion-reaction-fractionation modelling 

Reinhard Well1, Dominika Lewicka-Szczebak2, Martin Maier3, and Amanda Matson1
Reinhard Well et al.
  • 1Thünen Institute, Climate-Smart Agriculture, Braunschweig, Germany (
  • 2Laboratory of Isotope Geology and Geoecology, Institute of Geological Sciences, University of Wrocław, Wrocław, Poland (
  • 3Department of Soil and Environment, The Forest Research Institute Baden-Württemberg, Freiburg, Germany (

Analysing isotopocule values of nitrous oxide (N2O) produced in soil can be used to distinguish N2O production pathways and to quantify N2O reduction to N2. In the field, this is typically accomplished by analysing gas samples collected from closed chambers and calculating the isotopocule values of soil-emitted N2O taking into account the fraction of atmospheric N2O. Accuracy of this approach is often limited when N2O fluxes are low, leading to small fraction of soil-derived N2O in the chamber gas. To overcome this limitation, some studies used N2O isotopocules of soil air, assuming that these reflected N2O produced in soil (Gallarotti et al., 2021, Zou et al., 2014). However, this can lead to inaccurate results because (i) due to bi-directional diffusive gas exchange with the atmosphere, soil air is a mixture of soil-derived and atmospheric N2O and (ii) isotopic fractionation during diffusive flux to the atmosphere leads to enrichment of residual N2O in soil air. To evaluate these confounding factors and develop an approach to determine isotopocules of N2O produced in soil from soil air samples, we compared surface fluxes of N2O isotopocules determined by the closed chamber method (Lewicka-Szczebak et al. 2020) with gas probe data. Moreover, a diffusion-reaction model (Maier et al., 2017, Well et al., 2019) will be extended to include isotopic fractionation in order to determine isotopocule values of produced N2O from soil air data. Scenarios varying in depth–dependent N2O production and diffusivity will be analyzed. Results will show to which extent soil air and production values differ, which bias is obtained by using uncorrected soil air values, how well values can be corrected by modeling, and under which conditions soil air sampling might lead to better performance than closed chamber sampling. We expect that soil air sampling can lead to improved sensitivity for isotopocule values of soil-derived N2O in certain cases, but correction of data is obligate to obtain useful results.



End Text



Gallarotti N, Barthel M, Verhoeven E et al. (2021) In-depth analysis of N2O fluxes in tropical forest soils of the Congo Basin combining isotope and functional gene analysis. The ISME Journal, 15, 3357-3374.

Lewicka-Szczebak D, Lewicki MP, Well R (2020) N2O isotope approaches for source partitioning of N2O production and estimation of N2O reduction – validation with the 15N gas-flux method in laboratory and field studies. Biogeosciences, 17, 5513-5537.

Maier M, Longdoz B, Laemmel T, Schack-Kirchner H, Lang F (2017) 2D profiles of CO2, CH4, N2O and gas diffusivity in a well aerated soil: measurement and Finite Element Modeling. Agricultural and Forest Meteorology, 247, 21-33.

Well R, Maier M, Lewicka-Szczebak D, Köster JR, Ruoss N (2019) Underestimation of denitrification rates from field application of the N-15 gas flux method and its correction by gas diffusion modelling. Biogeosciences, 16, 2233-2246.

Zou Y, Hirono Y, Yanai Y, Hattori S, Toyoda S, Yoshida N (2014) Isotopomer analysis of nitrous oxide accumulated in soil cultivated with tea (Camellia sinensis) in Shizuoka, central Japan. Soil Biology & Biochemistry, 77, 276-291.

How to cite: Well, R., Lewicka-Szczebak, D., Maier, M., and Matson, A.: Determination of nitrous oxide processes in soil from depth profiles of natural abundance stable isotope values by diffusion-reaction-fractionation modelling , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7043,, 2022.