Accounting for Solution Composition in a Plant Roots Active Nutrient Uptake Model

The objective of this study was to include the nutrient uptake deficiency stress in the generic multicomponent transport model, HP1 (the geochemical code PHREEQC coupled to the transient water and solute transport model HYDRUS-1D). The first step was the incorporation of a combined passive- active root nutrient uptake model in HP1 (Jacques et al., 2006). The nutrient uptake model is based on the model of Silberbush et al. (2005). For example, Ca is taken up by passive and active processes, in which the parameters of the Michaelis-Menten active uptake model depend on the solution chemistry. Simulations were compared with experimental data from four irrigation treatments with different Na(-Cl) concentrations. The results are a preliminary attempt to predict uptake of different ions under varying conditions of salinity. Results for Na and K are promising.