Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting

E Harris, E Diaz-Pines, E Stoll, M Schloter, S Schulz, C Duffner, Kexue Li, Katie Moore, J Ingrisch, D Reinthaler, S Zechmeister-Boltenstern, S Glatzel, N Bruggemann, M Bahn

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Abstract

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N 2O emissions result from soil N fertilization, which is converted to N 2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N 2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N 2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N 2O emission pathways are sufficient to account for the accelerating N 2O growth rate observed over the past decade.

Original languageEnglish
Article numbereabb7118
JournalScience Advances
Volume7
Issue number6
DOIs
Publication statusPublished - 5 Feb 2021

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