The effect of a constant efflux on solute movement to a root

This paper presents two analytical solutions to solute uptake and release by a root (the root exhibits efflux) when both mass and diffusive flows are considered and the water content of the soil is maintained constant. The first solution is for a constant solute concentration at some finite distance from the root, while the second is when there is no solute recharge from the soil outside a cylinder coaxle with the root.Several examples are presented to show the effect of the effluxive term. It is shown that the point where the ratio of efflux to initial ion concentration in solution is equal to the difference between root absorbing power and water flux at the root, is critical to nutrient depletion or buildup at the root surface. It is also shown for the case of no recharge that the concentration profiles when efflux is considered are markedly different than where efflux is not considered.Contribution from the Purdue Agric. Exp. Stn., West Lafayette, IN, 47907. Journal Paper Number7458.