Gradients in the rhizosphere Longitudinal lateral gradients: Nutrient concentration *Depends on balance between soil supply and plant uptake; depending in turn on Concentrations in bulk soil mobility in soil solution mass flow rate water content of soil rate of uptake into roots interactions with microorganismsGradients in the rhizosphere Longitudinal & lateral gradients: Mycorrhizal & other fungi - concentrations & composition - population density & composition Nutrient concentration Depends on balance between soil supply and plant uptake; depending in turn on: • Concentrations in bulk soil • mobility in soil solution • mass flow rate • water content of soil • rate of uptake into roots • interactions with microorganisms