1. Combining the 15 N Gas Flux Method and N 2 O Isotopocule Data for the Determination of Soil Microbial N 2 O Sources.
- Author
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Micucci G, Lewicka-Szczebak D, Sgouridis F, Well R, Buchen-Tschiskale C, McNamara NP, Krause S, Lynch I, Roos F, and Ullah S
- Subjects
- Soil chemistry, Bacteria metabolism, Bacteria classification, Nitrification, Monte Carlo Method, Fungi metabolism, Bayes Theorem, Nitrogen Isotopes analysis, Nitrous Oxide analysis, Nitrous Oxide metabolism, Nitrous Oxide chemistry, Soil Microbiology, Denitrification
- Abstract
Rationale: The analysis of natural abundance isotopes in biogenic N
2 O molecules provides valuable insights into the nature of their precursors and their role in biogeochemical cycles. However, current methodologies (for example, the isotopocule map approach) face limitations, as they only enable the estimation of combined contributions from multiple processes at once rather than discriminating individual sources. This study aimed to overcome this challenge by developing a novel methodology for the partitioning of N2 O sources in soil, combining natural abundance isotopes and the use of a15 N tracer (15 N Gas Flux method) in parallel incubations., Methods: Laboratory incubations of an agricultural soil were conducted to optimize denitrification conditions through increased moisture and nitrate amendments, using nitrate that was either15 N-labeled or unlabeled. A new linear system combined with Monte Carlo simulation was developed to determine N2 O source contributions, and the subsequent results were compared with FRAME, a Bayesian statistical model for stable isotope analysis., Results: Our new methodology identified bacterial denitrification as the dominant process (87.6%), followed by fungal denitrification (9.4%), nitrification (1.5%), and nitrifier denitrification (1.6%). Comparisons with FRAME showed good agreement, although FRAME estimated slightly lower bacterial denitrification (80%) and higher nitrifier-denitrification (9%) contributions., Conclusions: This approach provides an improved framework for accurately partitioning N2 O sources, enhancing understanding of nitrogen cycling in agroecosystems, and supporting broader environmental applications., (© 2024 The Author(s). Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.)- Published
- 2025
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