RATIONALE: The emission of dinitrogen (N ₂ ) gas from soil is the most poorly constrained flux in terrestrial nitrogen (N) budgets because the high background atmospheric N ₂ concentration makes soil N ₂ emissions difficult to measure. In this study, we tested the theoretical and analytical feasibility of using the N ₂ /Ar technique to measure soil‐atmosphere N ₂ fluxes. METHODS: Dual inlet isotope ratio mass spectrometry was used to measure δAr/N ₂ values of gas sampled from surface flux chambers. In laboratory experiments using dry sand in a diffusion box, we induced a known steady‐state flux of N ₂ , and then measured the change in the N ₂ /Ar ratio of chamber headspace air samples to test our ability to reconstruct this flux. We m\odeled solubility, thermal, and water vapor flux fractionation effects on the N ₂ /Ar ratio to constrain physical effects on the measured N ₂ flux. RESULTS: In dry sand, an actual N ₂ flux of 108 mg N m ^–2 day ^–1 was measured as 111 ± 19 mg N m ^–2 day ^–1 (± standard error (SE)). In wet sand, an actual N ₂ flux of 160 mg N m ^–2 day ^–1 was measured as 146 ± 20 mg N m ^–2 day ^–1 when solubility and water vapor flux fractionation were taken into account. Corrections for thermal fractionation did not improve estimates of N ₂ fluxes. CONCLUSIONS: We conclude that our application of the N ₂ /Ar technique to soil surface fluxes is valid only above a detection limit of approximately 108 mg N m ^–2 day ^–1 . The N ₂ /Ar method is currently best used as a validation tool for other methods in ecosystems with high soil N ₂ fluxes, but, with future improvements, it holds promise to provide high‐resolution measurements in systems with low soil N ₂ fluxes. Copyright © 2012 John Wiley & Sons, Ltd.

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