Journal
BIOGEOCHEMISTRY
Volume 149, Issue 3, Pages 239-250Publisher
SPRINGER
DOI: 10.1007/s10533-020-00672-9
Keywords
Nitrous oxide; Nitric oxide; NOx; N2O; Drying-rewetting; Nitrogen deposition
Funding
- National Science Foundation [DEB 1405525, 1656062, 1916622]
- Environmental Protection Agency STAR Graduate Fellowship
- Ford Foundation
- USDA NIFA [CA-R-PPA-5101-CG]
- NIFA Hatch [CA-R-PPA-5093-H]
- University of California Natural Reserve System [10.21973/N3V66D]
- Direct For Biological Sciences [1916622] Funding Source: National Science Foundation
- Division Of Environmental Biology [1916622] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [1656062] Funding Source: National Science Foundation
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Nitrogen (N) trace gas emission pulses produced after wetting dry soils may be important pathways of ecosystem N loss. However, the rates and mechanisms controlling these emissions remain unclear. We tested whether changes in microbial community structure and increased rates of atmospheric N deposition could explain N emissions at two desert sites differing in atmospheric N deposition by similar to six fold. We measured peak NOx (sum of nitric oxide and nitrogen dioxide) emissions 12 h post-wetting. NOx emissions remained elevated over 24 h and increased after adding N. In contrast, we measured the highest nitrous oxide (N2O) emissions within only 15 min post-wetting. N2O emissions decreased within 12 h, were insensitive to adding N, and were among the highest reported globally. Microbial communities at the high N deposition site were less diverse with higher 16S nitrifier and bacterial amoA gene abundances relative to the low N deposition site, suggesting an increased capacity for nitrification. Nevertheless, N emissions were lower at the high N deposition site. While microbial communities changed after wetting, these changes were not correlated with N emissions. We conclude that desert soils can produce substantial NOx and N2O emission pulses, but that these emissions do not appear directly governed by changing microbial community characteristics or higher atmospheric N inputs. These findings highlight the importance of gaseous N loss pathways from dryland ecosystems that may contribute to sustained N limitation, with implications for atmospheric chemistry and Earth's climate.
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