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| Titel |
A systematic study of pre-incubation on the release of nitric oxide from arid soils |
| VerfasserIn |
T. Behrendt, M. Bruse, B. Mamtimin, M. O. Andreae, F. X. Meixner |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250065091
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| Zusammenfassung |
| There is microbial activity in nearly in all terrestrial soils, since primeval times. During the
last decades, an increasing number of laboratory studies on biogenic nitric oxide (NO)
emission from dryland became available. However, the fast adaptation of microbes to
changing environmental conditions, which is known as the “lab rat effect”, may cause a series
of problems for these studies. Particularly, the question of initial conditions and standardized
preparation (e.g. pre-incubation) is not well investigated. These parameters are very
important to make different studies comparable, especially for a comparison between usually
dry arid soils and organic rich, usually wet mid-latitude soils. The length of the
pre-incubation period, the (controlled) soil temperature and soil water content seem to be the
most variable parameters. Pre-incubation of (air-dried) soil samples from semi-arid, arid, and
hyper-arid regions has been considered as an effective measure to avoid the so-called
“pulsing effect”, a strong and sudden enhancement of NO release from re-wetted
of completely dry soil. However, in a lot of previous studies, the increase of NO
release after rewetting is considered generally as “pulsing”. However, this could be
misleading, because NO release depends strongly on the initial soil water content
before re-wetting. For that reason, we define “pulsing” more specifically: it is the
increase of the NO release rate over the entire range of soil water content during an
experiment with a given (non-zero) pre-incubation length compared to the NO
release rate over the entire range of soil water content during an experiment of no
pre-incubation.
We present results of a systematic study on different soil samples from the Gobi desert
(Mongolia) and from the Taklimakan desert (NW-China). These samples have been exposed
to different time periods of pre-incubation (0, 3, 12, 48 and 192 hours) under constant soil
temperature (25Ë C) and soil water content (field capacity, pF1.8). Afterwards, the soil
samples have been fumigated within an automated dynamic soil chamber system and the net
release of NO has been determined as a function of soil temperature and soil water content
(WFPS). While the NO release shows an exponential relationship on soil temperature (Q10
about 2), the dependence on WFPS follows an optimum curve with a single maximum at
WFPS |
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