Quantifying citrate-enhanced phosphate root uptake using microdialysis.

A single root exuding citrate at a typical rate (4.3 × 10-5 μmol m-1 of root h-1) did not contribute significantly to P uptake. Microdialysis probes show promise for measuring rhizosphere processes when calibration experiments and mathematical modelling are used to decouple microdialysis and rhizosphere mechanisms.