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Stable isotopic analyses of soil-emitted N₂O (<i>δ</i>¹⁵N^bulk, <i>δ</i>¹⁸O and <i>δ</i>¹⁵N^sp = ¹⁵N site preference within the linear N₂O molecule) may help to quantify N₂O reduction to N₂, an important but rarely quantified process in the soil nitrogen cycle. The N₂O residual fraction (remaining unreduced N₂O, <i>r</i>_N₂O) can be theoretically calculated from the measured isotopic enrichment of the residual N₂O. However, various N₂O-producing pathways may also influence the N₂O isotopic signatures, and hence complicate the application of this isotopic fractionation approach.<br><br> Here this approach was tested based on laboratory soil incubations with two different soil types, applying two reference methods for quantification of <i>r</i>_N₂O: helium incubation with direct measurement of N₂ flux and the ¹⁵N gas flux method. This allowed a comparison of the measured <i>r</i>_N₂O values with the ones calculated based on isotopic enrichment of residual N₂O. The results indicate that the performance of the N₂O isotopic fractionation approach is related to the accompanying N₂O and N₂ source processes and the most critical is the determination of the initial isotopic signature of N₂O before reduction (<i>δ</i>₀). We show that <i>δ</i>₀ can be well determined experimentally if stable in time and then successfully applied for determination of <i>r</i>_N₂O based on <i>δ</i>¹⁵N^sp values. Much more problematic to deal with are temporal changes of <i>δ</i>₀ values leading to failure of the approach based on <i>δ</i>¹⁵N^sp values only. For this case, we propose here a dual N₂O isotopocule mapping approach, where calculations are based on the relation between <i>δ</i>¹⁸O and <i>δ</i>¹⁵N^sp values. This allows for the simultaneous estimation of the N₂O-producing pathways' contribution and the <i>r</i>_N₂O value.