Vacancy: PhD thesis offer: Establish a multi-scale model of the electrical signature of plant root architecture

Scientific context

Geophysical techniques, such as electrical resistivity tomography (ERT), are more and more used as a tool to assess spatio-temporal soil moisture dynamics of cropped soils. Yet, the variability in space and time of the pedophysical relationship remains an important challenge, especially in the presence of growing roots. In most studies, an effect of root biomass on bulk EC is observed, but not yet well understood and thus this effect is not compensated for the estimation of soil moisture content. It has been shown that bulk electrical resistivity from ERT is correlated with root density or root length density. However, the electrical properties of root segments, the effect of the full root architecture and the combination with heterogeneous porous media have not been fully addressed.

This PhD aims at developing a multi-scale model to represent the electrical processes taking place in the soil-plant continuum under an external electric field. At the microscopic scale a novel model that considers polarization from soil over rhizosphere to root tissue, as well as the polarization processes along and around roots, need to be developed. The effect of different root system characteristics on these properties will be addressed. Based on an electrical model for individual root segments, electrical parameterizations of complete, growing root architectures will be developed. Existing root growth and soil water models will have to be combined with the electrical models, allowing the prediction and study of effective soil-root electrical properties as well as the calibration of corresponding biopedophysical relationships. Besides the modelling efforts, the PhD candidate will assist in the execution of experiments on root segments and individual plants with varying root architectures.

Location

Université catholique de Louvain, Earth and Life Institute, Louvain-la-Neuve (Belgium).

The PhD is part of a larger research project in which 3 PhD students will collaborate to understand and quantify the signature of plant roots in electrical, geophysical properties of soils under vegetation with the long-term aim of improved soil moisture and root activity monitoring. Related research topics are investigated by partners at the University of Bonn and the Forschungszentrum Jülich in Germany in close cooperation. Stay abroad at the University of Bonn (Andreas Kemna) and/or Forschungszentrum Jülich (Sander Huisman) of at least 6 months has to be taken into account.

Profile & requested skills

The candidate must hold a Master degree (obtained after 2012) whose training focuses on engineering/bioengineering/physics/geosciences. Aptitude for teamwork, good spoken and written English will be appreciated.

Allowance

Allocation of a PhD grant from the Walloon scientific research fund FNRS.

Supervisors

- Mathieu Javaux (UCL)/ Frederic Nguyen (ULg)

Application Deadline

Candidates must send a detailed CV and a motivation letter to Mathieu Javaux (Mathieu.javaux@uclouvain.be) before the January 8, 2016