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| Titel |
Nitrification and N2O production processes in soil incubations after ammonium fertilizer application at high concentrations |
| VerfasserIn |
Marianna Deppe, Reinhard Well, Anette Giesemann, Heinz Flessa |
| 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 |
250131837
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| Publikation (Nr.) |
 EGU/EGU2016-12282.pdf |
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| Zusammenfassung |
| High concentrations of ammonium as they occur, e.g., after point-injection of ammonium
fertilizer solution according to the CULTAN fertilization technique may retard nitrification.
Potential advantages in comparison to conventional fertilization include a higher N efficiency
of crops, reduced nitrate leaching, and lower N2O and N2 emissions. Dynamics of
nitrification due to plant uptake and dilution processes, leading to decreasing ammonium
concentrations in fertilizer depots, has only poorly been studied before. Furthermore, there is
little information about the relative contribution of different N2O production processes
under these conditions. To elucidate the process dynamics a laboratory incubation
study was conducted. After fertilization with ammonium sulfate at 5 levels (from
0 to 5000 mg NH4+-N kg−1; 20mg NO3−-N kg−1 each), sandy loam soil was
incubated in dynamic soil microcosms for 21 days. N2O, CH4 and CO2 fluxes
as well as isotope signatures of N2O and, at three dates, NO3− and NH4+ were
measured. To identify N2O production processes, acetylene inhibition (0.01 vol.%),
15N tracer approaches, and isotopomer data (15N site preference and δ18O) were
used.
N2O emissions were highest at 450mg NH4+-N kg−1 and declined with further increasing
concentrations. At 5000 mg NH4+-N kg−1 nitrification was completely inhibited. However,
approximately 90% of N2O production was inhibited by acetylene application, and there was
no change in the relative contribution of nitrification and denitrification to N2O production
with N level.
Applying the non-equilibrium technique to our 15N tracer data revealed heterogeneous
distribution of denitrification in soil, with at least two distinct NO3− pools, and spatial
separation of NO3− formation and consumption. In comparison with the acetylene inhibition
and 15N tracer approaches the results of the isotopomer approach were reasonable and
indicated substantial contribution of nitrifier-denitrification (10-40%) to total N2O
production. |
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