A review of rhizosphere carbon flow modelling

Rhizosphere processes play a key role in nutrient cycling in terrestrial ec osystems. Plant rhizodeposits supply low-molecular weight carbon substrates to the soil microbial community, resulting in elevated levels of activity surrounding the root. Mechanistic compartmental models that aim to model ca rbon flux through the rhizosphere have been reviewed and areas of future re search necessary to better calibrate model parameters have been identified. Incorporating the effect of variation in bacterial biomass physiology on c arbon flux presents a considerable challenge to experimentalists and modell ers alike due to the difficulties associated with differentiating dead from dormant cells. A number of molecular techniques that may help to distingui sh between metabolic states of bacterial cells are presented. The calibrati on of growth, death and maintenance parameters in rhizosphere models is als o discussed. A simple model of rhizosphere carbon flow has been constructed and a sensitivity analysis was carried out on the model to highlight which parameters were most influential when simulating carbon flux. It was obser ved that the parameters that most heavily influenced long-term carbon compa rtmentalisation in the rhizosphere were exudation rate and biomass yield. I t was concluded that future efforts to simulate carbon flow in the rhizosph ere should aim to increase ecological realism in model structure.