Preprints
https://doi.org/10.5194/bg-2018-280
https://doi.org/10.5194/bg-2018-280
05 Jul 2018
 | 05 Jul 2018
Status: this preprint was under review for the journal BG but the revision was not accepted.

A mechanistic model for electrical conduction in soil–root continuum: a virtual rhizotron study

Sathyanarayan Rao, Félicien Meunier, Solomon Ehosioke, Nolwenn Lesparre, Andreas Kemna, Frédéric Nguyen, Sarah Garré, and Mathieu Javaux

Abstract. Electrical Resistivity Tomography (ERT) has become an important tool to study soil water fluxes in cropped field. ERT results translates to water content via empirical pedophysical relations that take soil physical properties into account, usually ignoring the impact of roots. Studies shows high root dense soils behaves quite differently than less root dense soils in terms of bulk electrical conductivity. Yet, we do not completely understand the impact of root segments on the ERT measurements. In this numerical study, we coupled an electrical model with a plant-soil water flow model to investigate the impact of plant root growth and water uptake on the ERT virtual experiment. The electrical properties of roots were explicitly accounted in the finite element mesh and we obtained the electrical conductivities of root segments by conducting specific experiments on real maize plants. The contrast between electrical conductivity of roots and soil depends on factors such as root density, irrigation, root age, and root water uptake pattern. Root growth and water uptake processes thus affect this contrast together with the soil electrical properties. Model results indicate a non-negligible anisotropy in bulk electrical conductivity induced by root processes. We see a greater anisotropy in a sandy medium when compared to a loamy medium. We find that the water uptake process dominates the bulk electrical properties. The Gauss-Newton type ERT inversion of virtual rhizotron data demonstrate that, when root-soil electrical conductivity contrasts are high, it can lead to error in water content estimates since the electrical conductivity is partly due to root. Thus, incorporating the impact of root in the pedophysical relations is very important to interpret ERT results directly as water content.

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Sathyanarayan Rao, Félicien Meunier, Solomon Ehosioke, Nolwenn Lesparre, Andreas Kemna, Frédéric Nguyen, Sarah Garré, and Mathieu Javaux
 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Sathyanarayan Rao, Félicien Meunier, Solomon Ehosioke, Nolwenn Lesparre, Andreas Kemna, Frédéric Nguyen, Sarah Garré, and Mathieu Javaux
Sathyanarayan Rao, Félicien Meunier, Solomon Ehosioke, Nolwenn Lesparre, Andreas Kemna, Frédéric Nguyen, Sarah Garré, and Mathieu Javaux

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Latest update: 23 Jun 2024
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Short summary
This paper illustrates the impact of electrical property of maize root segments on the Electrical Resistivity Tomography (ERT) inversion results with the help of numerical model. The model includes explicit root representation in the finite element mesh with root growth, transpiration and root water uptake. We show that, ignoring root segments could lead to wrong estimation of water content using ERT method.
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