Modelling oxygen transport in soil with plant root and microbial oxygen consumption: Depth of oxygen penetration

Cook F.J., Knight J.H. and Kelliher F.M. (2013) Modelling oxygen transport in soil with plant root and microbial oxygen consumption: Depth of oxygen penetration. Soil Research, 51 6: 539-553. doi:10.1071/SR13223


Author Cook F.J.
Knight J.H.
Kelliher F.M.
Title Modelling oxygen transport in soil with plant root and microbial oxygen consumption: Depth of oxygen penetration
Journal name Soil Research   Check publisher's open access policy
ISSN 1838-675X
1838-6768
Publication date 2013-11-01
Year available 2013
Sub-type Article (original research)
DOI 10.1071/SR13223
Open Access Status
Volume 51
Issue 6
Start page 539
End page 553
Total pages 15
Place of publication Collingwood, Australia
Publisher C S I R O Publishing
Language eng
Abstract A set of equations governing oxygen diffusion and consumption in soils has been developed to include microbial and plant-root sinks. The dependent variable is the transformed oxygen concentration, which is the difference between the gaseous concentration and a scaled value of the aqueous oxygen concentration at the root-soil interface. The results show how, as the air-filled porosity decreases, the reduced oxygen flux causes the depth of extinction to decrease. The results also show how the depth of extinction at a particular value of soil water content decreases with increasing temperature, due to increased microbial respiration. The critical value of water content at which the oxygen concentration goes to extinction at a finite depth was compared with alternative calculations with only a microbial sink. By ignoring the feedback of oxygen concentration on root uptake, the alternative calculations yielded substantially higher critical values of water content at all temperatures. Two soil oxygen diffusion coefficient functions from the literature were compared and shown to give significantly different critical values of water content for fine-textured soils, one more realistic than the other. A single relationship between the extinction depth and the ratio of the water content to the critical value was shown to apply for all temperatures and soil textures. The oxygen profiles were used along with a function relating redox potential to oxygen concentration to generate redox potential profiles. This application of the model could be useful in explaining soil biochemical processes in soils. For one such process, denitrification, the depth at which a critical oxygen concentration is reached was calculated as a function of the air-filled porosity and temperature of the soil. The implications of the critical value of soil water content in terms of water-filled pore space and matric potential are discussed in relation to the diffusion coefficient functions and recent literature. Journal compilation
Keyword Air-filled pore space
Denitrification
Diffusion coefficient function
Oxygen transport
Redox potential
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2014 Collection
 
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