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| Titel |
The effect of biological activity on soil water retention and diffusivity |
| VerfasserIn |
Burhan U. Choudhury, Stefano Ferraris, Rhys W. Ashton, David S. Powlson, William R. Whalley |
| 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 |
250126405
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| Publikation (Nr.) |
 EGU/EGU2016-6120.pdf |
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| Zusammenfassung |
| Root exudates of both living and artificial origins are known to affect various rhizosphere
microbial and micro-faunal activities. However, information on effects on root exudates on
soil hydraulic properties responsible for water transmission and distribution in the vadose
zone is inadequate, especially in dry soils. To study the effect of artificial root exudates
(carbohydrate, amino acids and organic acids mixture) on soil water retention and diffusion
process, a laboratory experiment was carried out using soil cores filled with air dried 2-mm
sieved loamy sand soils of Cambric Arenosol subclass. Root exudates at three concentrations
(1.25, 2.5 & 5.0 g C kg−1 dry soil) were added and the soil cores were saturated in distilled
water for 48 hours at 20 oC together with a control. To determine whether microbes have any
influence on diffusivity, two additional treatments with sterilization of microbes using
mercuric chloride solution (0.10%) in root exudates (2.5 g C kg−1 dry soil) and
distilled water saturated soil cores were studied. The water in the soil cores was
allowed to evaporate at constant temperature (20 ± 1oC) and at a relative humidity
of 0.3. The evaporation loss in terms of volumetric water content in the core was
measured regularly until the water content was constant with time. Soil water diffusivity
was determined numerically. To determine the water retention properties, soils
were saturated and incubated for 14 days at 20 oC with the same six treatments and
retention curves were generated for 8 different suctions, ranging from 0.01 bars to 15
bars.
Results revealed that evaporation from soil cores, initially at a uniform moisture content
of saturation, initially decreased linearly with the square root of time. The rate of decrease
was gradual in the root exudate treated soils but more rapid in soils treated to stop microbial
activity. Addition of root exudates considerably decreased the diffusivity compared to a
control treatment. By stopping soil microbial activity, with the addition of mercuric
chloride, soil water diffusivity increased in comparison with biologically active soils. |
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