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| Titel |
CO2 emissions from organic soils under agricultural use |
| VerfasserIn |
Cédric Bader, Jens Leifeld, Moritz Müller, Rainer Schulin |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250101638
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| Publikation (Nr.) |
 EGU/EGU2015-822.pdf |
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| Zusammenfassung |
| The organic soils of peatlands represent a major global sink for terrestrial carbon.
Agricultural use of organic soils requires drainage, changing conditions in these soils from
anoxic to oxic. As a consequence, the organic carbon that had been accumulated often over
millennia is rapidly mineralized, so that these soils then are no longer a sink but become a
source of CO2. The aim of our study is to analyse the amount and origin of CO2 emitted from
organic soils under three land-use types (forest, arable cropland and grassland). Our study
area is located in the Bernese Lakeland (CH). The peatlands of this region were drained in the
1870ies, and the site as well as the surrounding area are now managed by a state
prison. Since decades our study site is under the same land-use. In Oktober 2013 we
took 4 replicate soil cores of all land-uses with respect to a certain distance from
a major drainage ditch. Each core was analysed for its bulk density and carbon
content. 9 soil samples from a depth of 20-30 cm were analysed for their F14C
and /13C values and later divided into 18 subsamples. Half of them were mixed
with 0.2-0.4 g of labelled corn stalk enriched in /13C (/13C=2000) in order to
mimic plant residue inputs in the field. The moisture content of these samples was
equilibrated at a pF-value of 2 before incubating the samples in a Respicond VII
analyser for several weeks at 20Ë C. By trapping the respired CO2 in NaOH and
precipitating it as BaCO3 we were able to analyse its F14C and /13C value. This
enabled us to determine to what extent the CO2 originated from old peat, young
plant residues or the added maize stalk. Generally the cropland samples showed
the highest respiration rates, lowest F14C values and highest carbon stocks. The
organic soils under the forest were degraded the most and showed low respiration
rates. Analyzing the F14C values of the CO2 revealed that peat contributes most to
the respiration and its degradation is fastest in the cropland. Our findings suggest
that peat respiration must have been more intense under forest during the past 140
years. The addition of fresh plant material resulted in increased respiration rates but
supressed the respiration of old peat in the cropland and grassland (negative priming). |
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