Synthesis of Global Soil‐Emitted N 2 O Isotopic Signatures: Geoclimatic Patterns and Influential Factors

Abstract Nitrous oxide (N 2 O) is a potent greenhouse gas and major driver of stratospheric ozone depletion. Isotopic data constrain bottom‐up models, yet global natural‐abundance patterns remain poorly resolved. We compiled a global database of in situ soil‐emitted N 2 O isotopes from chamber‐ or probe‐based studies to examine the spatiotemporal variability and environmental controls. Croplands showed the greatest variability, with mean δ 15 N bulk , δ 18 O, and δ 15 N SP values of −15.0‰, 35.3‰, and 13.7‰; natural soils were slightly 15 N‐enriched, consistent with less anthropogenic influence. Using the Time‐resolved Fractionation and Mixing Evaluation (TimeFRAME) model, we estimated bacterial denitrification as the major N 2 O source process (45%–63%) and found a mean N 2 O reduction potential of 43%. Global distribution of isotope signatures reflected the edaphic drivers including positive δ 15 N SP –pH and negative δ 15 N bulk –moisture relationship. Overall, this global inventory provides empirically constrained isotopic end‐members for improved source–sink attribution, new insights into terrestrial N 2 O cycling, and a benchmark for model evaluation.