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| Titel |
Suppression of N2O and NO from denitrification by biochar: the role of pH |
| VerfasserIn |
Alfred Obia, Gerard Cornelissen, Jan Mulder, Peter Dörsch |
| 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 |
250114772
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| Publikation (Nr.) |
 EGU/EGU2015-15587.pdf |
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| Zusammenfassung |
| Denitrification reduces NO3- to N2 and returns excess nitrogen to the atmosphere. NO and N2O are gaseous intermediates of denitrification which, once escaped to the atmosphere, have adverse effects on chemistry and radiative forcing in the atmosphere. We studied the effect of biochar on denitrification and its gaseous intermediates in two acidic soils and tried to distinguish between the alkalizing effect of biochars on soil pH, and other, unknown effects of biochar on denitrification. Anoxic soil slurries were incubated with untreated biochars or biochars from which part of the alkalinity had been removed by water- and acid leaching. Soils amended with NaOH and uncharred cacao shell were used as controls. Biochar addition stimulated overall denitrification depending on biochar and soil type. This stimulation was not strictly coupled to pH increase, suggesting that biochar fueled respiration processes by contributing microbially available C. High resolution gas kinetics of NO, N2O and N2 showed that biochar amended soils induced denitrification enzymes earlier and with higher activity, resulting in less NO and N2O accumulation relative to N2 production. The extent to which biochar suppressed NO and N2O was dose-dependent and clearly related to the effective pH increase during incubation. Acid leaching of BC reduced or eliminated its ability to suppress N2O and NO net production. Comparison of BC with NaOH-amended soils showed that the reduction of N2O and NO net production was mainly an effect of increase in soil pH. Even though other factors supporting N2O reductase activity could not be excluded, our results indicate that soil pH increase might be an important driver behind the often-reported suppression of N2O emissions after biochar addition. |
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