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| Titel |
Source portioning of N2O emissions after long term elevation of soil temperature in a permanent grassland soil |
| VerfasserIn |
Anne Jansen-Willems, Gary Lanigan, Timothy Clough, Louise Andresen, Christoph Müller |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250137184
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| Publikation (Nr.) |
 EGU/EGU2016-18388.pdf |
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| Zusammenfassung |
| Several methods, such as source portioning, have been used to quantify the contributions of
individual N pools to N2O emissions. These methods however, assume the absence of hybrid
reactions such as co-denitrification, which were previously identified as important. A straight
forward method portioning N2O fluxes into four different production processes, including a
hybrid reaction, was therefore developed. This method portioned the N2O fluxes in
nitrification, denitrification, oxidation of organic matter and co-denitrification, using data
on 45R and 46R of the N2O flux and the 15N content of the NO3− and NH4+ in
the soil. This newly developed method was used to analyse the N2O emissions
from incubated soil, which was previously subjected to 6 years of elevated soil
temperature of +0, +1, +2 or +3 ˚ C. N2O emissions were measured and analysed at four
time points in the six days following, NO315NH4 Gly or 15NO3NH4 Gly, label
addition. The oxidation of organic N was found to be the main source of N2O fluxes at
all sampling dates, comprising between 63 and 85% of the total N2O flux. The
percentage contribution made by organic N to N2O fluxes increased over the sampling
period, rising from a minimum of 40% in the control treatment, to virtually 100%
across all treatments by Day 6. Compared to the control treatment, denitrification
contributed less to N2O from soil subjected to +2 and +3 ˚ C warming (p <0.0001 and
p=0.002, respectively). Co-denitrification only contributed to the N2O flux during
the first day after substrate addition. The highest amount of N2O produced via
co-denitrification was found under the control treatment. From soil subjected to +2 and +3 ˚
C treatments, the contribution of co-denitrification was minor. However, these differences in
co-denitrification were not significant. This research showed the importance of the
oxidation of organic N in N2O emissions. It should therefore not be omitted as a
potential source in source portioning. Emissions of N2O in the first six days after
fertilisation decreased for soils previously subjected to higher temperatures as a
consequence of a reduction in the rates of denitrification and the oxidation of organic N. |
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