Details
| Original language | English |
|---|---|
| Pages (from-to) | 278-287 |
| Number of pages | 10 |
| Journal | Journal of Plant Nutrition and Soil Science |
| Volume | 178 |
| Issue number | 2 |
| Publication status | Published - 1 Apr 2015 |
| Externally published | Yes |
Abstract
Oxygen (O2) supply and the related redox potential (EH) are important parameters for interactions between roots and microorganisms in the rhizosphere. Rhizosphere extension in terms of the spatial distribution of O2 concentration and EH is poorly documented under aerobic soil conditions. We investigated how far O2 consumption of roots and microorganisms in the rhizosphere is replenished by O2 diffusion as a function of water/air-filled porosity. Oxygen concentration and EH in the rhizosphere were monitored at a mm-scale by means of electroreductive Clark-type sensors and miniaturized EH electrodes under various matric potential ranges. Respiratory activity of roots and microorganisms was calculated from O2 profiles and diffusion coefficients. pH profiles were determined in thin soil layers sliced near the root surface. Gradients of O2 concentration and the extent of anoxic zones depended on the respiratory activity near the root surface. Matric potential, reflecting air-filled porosity, was found to be the most important factor affecting O2 transport in the rhizosphere. Under water-saturated conditions and near field capacity up to -200 hPa, O2 transport was limited, causing a decline in oxygen partial pressures (pO2) to values between 0 and 3 kPa at the root surface. Aerobic respiration increased by a factor of 100 when comparing the saturated with the driest status. At an air-filled porosity of 9% to 12%, diffusion of O2 increased considerably. This was confirmed by EH around 300 mV under aerated conditions, while EH decreased to 100 mV on the root surface under near water-saturated conditions. Gradients of pO2 and pH from the root surface indicated an extent of the rhizosphere effect of 10-20 mm. In contrast, EH gradients were observed from 0 to 2 mm from the root surface. We conclude that the rhizosphere extent differs for various parameters (pH, Eh, pO2) and is strongly dependent on soil moisture. Copyright
Keywords
- Air-filled porosity, Hotspots, Oxygen diffusion, Rhizosphere, Soil aeration
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Soil Science
- Agricultural and Biological Sciences(all)
- Plant Science
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In: Journal of Plant Nutrition and Soil Science, Vol. 178, No. 2, 01.04.2015, p. 278-287.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Oxygen and redox potential gradients in the rhizosphere of alfalfa grown on a loamy soil
AU - Uteau, Daniel
AU - Hafner, Silke
AU - Pagenkemper, Sebastian Kouso
AU - Peth, Stephan
AU - Wiesenberg, Guido L.B.
AU - Kuzyakov, Yakov
AU - Horn, Rainer
N1 - Publisher Copyright: © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - Oxygen (O2) supply and the related redox potential (EH) are important parameters for interactions between roots and microorganisms in the rhizosphere. Rhizosphere extension in terms of the spatial distribution of O2 concentration and EH is poorly documented under aerobic soil conditions. We investigated how far O2 consumption of roots and microorganisms in the rhizosphere is replenished by O2 diffusion as a function of water/air-filled porosity. Oxygen concentration and EH in the rhizosphere were monitored at a mm-scale by means of electroreductive Clark-type sensors and miniaturized EH electrodes under various matric potential ranges. Respiratory activity of roots and microorganisms was calculated from O2 profiles and diffusion coefficients. pH profiles were determined in thin soil layers sliced near the root surface. Gradients of O2 concentration and the extent of anoxic zones depended on the respiratory activity near the root surface. Matric potential, reflecting air-filled porosity, was found to be the most important factor affecting O2 transport in the rhizosphere. Under water-saturated conditions and near field capacity up to -200 hPa, O2 transport was limited, causing a decline in oxygen partial pressures (pO2) to values between 0 and 3 kPa at the root surface. Aerobic respiration increased by a factor of 100 when comparing the saturated with the driest status. At an air-filled porosity of 9% to 12%, diffusion of O2 increased considerably. This was confirmed by EH around 300 mV under aerated conditions, while EH decreased to 100 mV on the root surface under near water-saturated conditions. Gradients of pO2 and pH from the root surface indicated an extent of the rhizosphere effect of 10-20 mm. In contrast, EH gradients were observed from 0 to 2 mm from the root surface. We conclude that the rhizosphere extent differs for various parameters (pH, Eh, pO2) and is strongly dependent on soil moisture. Copyright
AB - Oxygen (O2) supply and the related redox potential (EH) are important parameters for interactions between roots and microorganisms in the rhizosphere. Rhizosphere extension in terms of the spatial distribution of O2 concentration and EH is poorly documented under aerobic soil conditions. We investigated how far O2 consumption of roots and microorganisms in the rhizosphere is replenished by O2 diffusion as a function of water/air-filled porosity. Oxygen concentration and EH in the rhizosphere were monitored at a mm-scale by means of electroreductive Clark-type sensors and miniaturized EH electrodes under various matric potential ranges. Respiratory activity of roots and microorganisms was calculated from O2 profiles and diffusion coefficients. pH profiles were determined in thin soil layers sliced near the root surface. Gradients of O2 concentration and the extent of anoxic zones depended on the respiratory activity near the root surface. Matric potential, reflecting air-filled porosity, was found to be the most important factor affecting O2 transport in the rhizosphere. Under water-saturated conditions and near field capacity up to -200 hPa, O2 transport was limited, causing a decline in oxygen partial pressures (pO2) to values between 0 and 3 kPa at the root surface. Aerobic respiration increased by a factor of 100 when comparing the saturated with the driest status. At an air-filled porosity of 9% to 12%, diffusion of O2 increased considerably. This was confirmed by EH around 300 mV under aerated conditions, while EH decreased to 100 mV on the root surface under near water-saturated conditions. Gradients of pO2 and pH from the root surface indicated an extent of the rhizosphere effect of 10-20 mm. In contrast, EH gradients were observed from 0 to 2 mm from the root surface. We conclude that the rhizosphere extent differs for various parameters (pH, Eh, pO2) and is strongly dependent on soil moisture. Copyright
KW - Air-filled porosity
KW - Hotspots
KW - Oxygen diffusion
KW - Rhizosphere
KW - Soil aeration
UR - http://www.scopus.com/inward/record.url?scp=84926162263&partnerID=8YFLogxK
U2 - 10.1002/jpln.201300624
DO - 10.1002/jpln.201300624
M3 - Article
AN - SCOPUS:84926162263
VL - 178
SP - 278
EP - 287
JO - Journal of Plant Nutrition and Soil Science
JF - Journal of Plant Nutrition and Soil Science
SN - 1436-8730
IS - 2
ER -