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| Titel |
Controls on microbial nitrogen use efficiency in soil |
| VerfasserIn |
Shasha Zhang, Lisa Noll, Qing Zheng, Yuntao Hu, Wolfgang Wanek |
| 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 |
250144093
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| Publikation (Nr.) |
 EGU/EGU2017-7878.pdf |
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| Zusammenfassung |
| Microbial nitrogen use efficiency (NUE) reflects the partitioning of organic N taken up
between (i) incorporation into microbial biomass and (ii) mineralization and release of N in
excess of microbial demand to the environment in the form of ammonium. Microbial NUE
therefore determines the availability of inorganic N in soils, influences subsequent inorganic
N transformation processes (e.g. nitrification) and may affect soil organic N sequestration
through assimilation and microbial turnover. While many studies in the past focused on
inorganic nitrogen transformation processes very few assessed microbial NUE and organic N
cycling processes. A recent study found that microbial NUE was strongly related to
resource C:N stoichiometry. However, if and how soil temperature and moisture
may affect microbial NUE and subsequent inorganic N processes has not yet been
studied.
To this end, mineral soils (0-10 cm) from an arable field, pasture and forest were sampled
from two adjacent sites differing in geology, Moarhof (limestone; 47˚ 31’N, 14˚ 4’ E) and
Gumpenstein (gneiss; 47˚ 30’ N, 14˚ 6’ E), Austria. Three short-term temperature (5, 15 and
25˚ C) and three soil moisture (30%, 60% and 90% water holding capacity) treatments
were applied to the soils in four replicates, respectively and gross rates of protein
depolymerization, N mineralization and nitrification and the corresponding immobilization
processes were measured with 15N-isotope pool dilution techniques. Three different 15N
tracers (mixture of 20 amino acids, (NH4)2SO4 and KNO3, 98 atom% 15N) were
added to the corresponding N pools and labeled soils were extracted with 1M KCl
solution after two incubation times for further analysis of N content and isotope
ratios.
We will present the data from these experiments and discuss major effects of soil
temperature and moisture on microbial NUE and soil inorganic N availability. This study will
thereby provide important parameters for terrestrial N cycle models where microbial NUE is
(if represented) often assumed as constant. |
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