Large nitrogen oxide emission pulses from desert soils and associated microbiomes
- Author(s): Eberwein, JR
- Homyak, PM
- Carey, CJ
- Aronson, EL
- Jenerette, GD
- et al.
Published Web Locationhttps://doi.org/10.1007/s10533-020-00672-9
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 ~ 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.