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| Titel |
Influence of 13 different biochars on N2O production and its sources during rewetting-drying cycles |
| VerfasserIn |
Nicole Wrage-Mönnig, Sebastian Fiedler, Teresa Fuertes-Mendizábal, José-Maria Estavillo, Jim A. Ippolito, Nils Borchard, Maria Luz Cayuela, Kurt Spokas, Jeff Novak, Claudia Kammann |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142021
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| Publikation (Nr.) |
 EGU/EGU2017-5592.pdf |
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| Zusammenfassung |
| Biochars have been found to have variable impacts on nitrous oxide (N2O) emissions. The
variability has been attributed to differences in soil – biochar properties and microbial
communities. While some information exists on biochar and soil properties, the effect of
biochars on microbial sources of N2O is still a matter of speculation. In this study, we tested
these effects for12 biochars prepared from cypress, loblolly pine and grape wood produced at
four different controlled temperatures (350, 500, 700 and 900˚ C), respectively, plus a
grapevine Kontiki biochar (600-700˚ C).
The biochars were added (2%) to a loamy sand brought to pH 7.1 with CaO. The
treatments plus one control were pre-incubated at 40% water holding capacity (WHC) for
four days. Then, they were brought to 80% WHC and 15N-nitrate was added (50 mg NO3−-N
kg−1 soil, 10% enriched in 15N). All treatments were set up with four replicates. In total,
three cycles of (re)wetting – drying (80 to 40% WHC, total duration 20 days) were
monitored. Samples for analyses of N2O concentrations and stable isotope signatures
were taken daily (except for weekends) after closing the incubation vessels for 90
minutes.
N2O emissions increased with each addition of water and decreased during drying to
background values. Each rewetting led to larger emissions than measured in the previous
cycle for all treatments including controls. All biochars decreased total N2O emissions
compared to the control treatments. The higher the production temperature of the biochar, the
larger usually the emission reduction. Largest effects were found for the grape wood and the
Kontiki biochars. Interestingly, the addition of biochars also changed the isotopic signatures
of the emitted N2O. Whereas emissions in the controls were enriched to about 5
atom% 15N excess at peak emissions, the enrichment was usually less after addition
of biochars (1-5 atom% excess). Again, this effect tended to be larger at higher
production temperatures of the biochars and was greatest for the grape wood and Kontiki
biochars.
The results indicate that NO3− was an important source for N2O emissions under the
conditions of the study, probably by denitrification. The addition of biochars changed not
only the amount of emissions, but also the N source of emissions. In this study, N2O
production from labelled NO3− was a smaller source of emissions after addition of biochars
(especially produced at high temperatures) than in control treatments. This indicates that the
15N-NO3− source was diluted by (accelerated) mineralization-nitrification or that microbial
sources using other substrates but added NO3− contributed more to N2O production.
Whether potential capture of NO3− by biochars could contribute to this, needs to be further
investigated.
Acknowledgements: This contribution was made possible by the ‘DesignChar4Food’
project (D4F) funded by the BLE and FACCE-JPI (German partners), by FACCE-CSA
nº 276610/MIT04-DESIGN-UPVASC and IT-932-16 (Spanish partners), and the
USDA-National Institute of Food and Agriculture (Project # 2014-35615-21971; US
colleagues) plus USDA-ARS CHARnet and GRACENetprograms. CK gratefully
acknowledges funding by DFG grant KA3442/1-1 and “OptiChar4EcoVin” (Hessian
Ministry for Higher Education, Research and the Arts). |
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