Cite as:
Moser, G.; Gorenflo, A.; Brenzinger, K.; Keidel, L.; Braker, G.; Marhan, S.; Clough, T.J. &amp; M&uuml;ller, C. (2018): <b>Explaining the doubling of N2O emissions under elevated CO2 in the Giessen FACE via in-field 15N tracing</b>. <i>Global Change Biology</i> <b>24</b>, 3897-3910<br>DOI: <a href="" target="_blank"></a>.

Resource Description

Title: Explaining the doubling of N2O emissions under elevated CO2 in the Giessen FACE via in-field 15N tracing
F2Fdw ID: 131
Publication Date: 2018-01-12
License and Usage Rights: FACE2FACE data user agreement.
Resource Owner(s):
Individual: Moser, Gerald
Individual: Gorenflo, André
Individual: Brenzinger, Kristof
Individual: Keidel, Lisa
Individual: Braker, Gesche
Individual: Marhan, Sven
Individual: Clough, Timothy J.
Individual: Müller, Christoph
Rising atmospheric CO2 concentrations are expected to increase nitrous oxide (N2O)<br/> emissions from soils via changes in microbial nitrogen (N) transformations. Several<br/> studies have shown that N2O emission increases under elevated atmospheric CO2<br/> (eCO2), but the underlying processes are not yet fully understood. Here, we present<br/> results showing changes in soil N transformation dynamics from the Giessen Free Air<br/> CO2 Enrichment (GiFACE): a permanent grassland that has been exposed to eCO2,<br/> +20% relative to ambient concentrations (aCO2), for 15 years. We applied in the field<br/> an ammonium-nitrate fertilizer solution, in which either ammonium (NHþ<br/> 4 ) or nitrate<br/> (NO<br/> 3 ) was labelled with 15N. The simultaneous gross N transformation rates were<br/> analysed with a 15N tracing model and a solver method. The results confirmed that<br/> after 15 years of eCO2 the N2O emissions under eCO2 were still more than twofold<br/> higher than under aCO2. The tracing model results indicated that plant uptake of NHþ<br/> 4<br/> did not differ between treatments, but uptake of NO<br/> 3 was significantly reduced under<br/> eCO2. However, the NHþ<br/> 4 and NO<br/> 3 availability increased slightly under eCO2. The<br/> N2O isotopic signature indicated that under eCO2 the sources of the additional emissions,<br/> 8,407 lg N2O–N/m2 during the first 58 days after labelling, were associated<br/> with NO<br/> 3 reduction (+2.0%), NHþ<br/> 4 oxidation (+11.1%) and organic N oxidation<br/> (+86.9%). We presume that increased plant growth and root exudation under eCO2<br/> provided an additional source of bioavailable supply of energy that triggered as a priming<br/> effect the stimulation of microbial soil organic matter (SOM) mineralization and<br/> fostered the activity of the bacterial nitrite reductase. The resulting increase in incomplete<br/> denitrification and therefore an increased N2O:N2 emission ratio, explains the<br/> doubling of N2O emissions. If this occurs over a wide area of grasslands in the future,<br/> this positive feedback reaction may significantly accelerate climate change.
| climate change | elevated CO2 | grassland | free air carbon dioxide enrichment | long-term response | N transformation | N2O emission | positive climate change feedback |
Literature type specific fields:
Journal: Global Change Biology
Volume: 24
Page Range: 3897-3910
Metadata Provider:
Individual: Toelle, Merja
Online Distribution:
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