| Bioavailability of metals has always been a complicated concept because many chemical, physical and biological processes are involved, such as metal speciation, soil and solution chemical kinetics, solute flow to (metal) and from (exudates) the root surface, plant genotype specific responses to stress and microbial processes. A full understanding of the concept, and of determining factors needs an integrating approach using models to bridge the gap between spatial resolution of sampling techniques and the supposed scale of heterogeneity of rhizosphere processes. This project aims to identify processes controlling metal bioavailability in the rhizosphere by integrating chemistry, physics and biology. A unique combination of a new powerful and flexible modelling framework (ORCHESTRA), unbiased rhizosphere sampling, the Donnan Membrane Technique in combination with high resolution analyses of metals will elucidate the governing processes in the rhizosphere complex and lead to an integrative understanding of the concept of bioavailability that has long been plead for, but has never been feasible before. Zinc bioavailability in Zn deficient soils will be investigated as a case study. The methodology, however, will be generalized such that it can be used to unify competing claims that are based on simplified approaches and to evaluate the concept of bioavailability in a much broader context. |
