Fig. 2.

Schematic of the different regions used in the mathematical formulation of the problem. The bulk and rhizosphere regions are highlighted with the modelling domains ${\Omega }_r,$ ${\Gamma }_{0r},$ ${\Gamma }_{0h},$ ${\Gamma }_{sr},$ ${\Gamma }_{ar},$ and ${\Gamma }_{rb}$labelled for the rhizosphere and ${\Omega }_b,$ ${\Gamma }_{sb}$and ${\Gamma }_{ab}$labelled for the bulk soil. (This figure is available in colour at JXB online.)