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| Titel |
Reducing fertilizer-derived N2O emission: Point injection vs. surface application of ammonium-N fertilizer at a loamy sand site |
| VerfasserIn |
Marianna Deppe, Reinhard Well, Anette Giesemann, Martin Kücke, Heinz Flessa |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082950
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| Zusammenfassung |
| N2O emitted from soil originates either from denitrification of nitrate and/or nitrification of
ammonium. N fertilization can have an important impact on N2O emission rates.
Injection of nitrate-free ammonium-N fertilizer, in Germany also known as CULTAN
(Controlled Uptake Long-Term Ammonium Nutrition), results in fertilizer depots with
ammonium concentrations of up to 10 mg N g-1 soil-1. High concentrations of
ammonium are known to inhibit nitrification. However, it has not yet been clarified
how N2O fluxes are affected by CULTAN. In a field experiment, two application
methods of nitrogen fertilizer were used at a loamy sand site: Ammonium sulphate
was applied either by point injection or by surface application. 15N-ammonium
sulphate was used to distinguish between N2O originating from either fertilizer-N or
soil-N. Unfertilized plots and plots fertilized with unlabeled ammonium sulphate
served as control. N2O emissions were measured using static chambers, nitrate and
ammonium concentrations were determined in soil extracts. Stable isotope analysis
of 15N in N2O, nitrate and ammonium was used to calculate the contribution of
fertilizer N to N2O emissions and the fertilizer turnover in soil. 15N analysis clearly
indicated that fertilizer derived N2O fluxes were higher from surface application plots.
For the period of the growing season, about 24% of the flux measured in surface
application treatment and less than 10% from injection treatment plots originated
from the fertilizer. In addition, a lab experiment was conducted to gain insight into
processes leading to N2O emission from fertilizer depots. One aim was to examine
whether the ratio of N2O to nitrate formation differs depending on the ammonium
concentration. Loamy sand soil was incubated in microcosms continuously flushed
with air under conditions favouring nitrification. 15N-labeled nitrate was used to
differentiate between nitrification and denitrification. Stable isotope analyses of 15N were
performed on N2O in the gas phase and on ammonium and nitrate extracted from soil
samples. |
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