A Dynamic Modeling of the PH of Soils Around Roots of Plants

Abstract

The relations between nutrients uptake, metabolism of the plants and pH are central in the study of the nutrition of plants and in particular the pH of the soil near the roots of plants has a great effect on different processes that occurs in the root rhizosphere. This work examines the capacity by the roots to change the pH of the soil around the roots by means of the formulation of a model of convectiondiffusion for a growing root system. Unlike previous models (Nye, Plant and Soil, 61:726 (1981); Kim and Silk, Plant, Cell & Environment, 22: 1527-1538 (1999)), the model is formulated through a one-dimensional moving boundary model. The same is solved by immobilization of the domain and application of the finite element method. Using typical experimental values predictions for the profile of pH between the root surface and the outer edge of the rhizosphere versus the time as a function of typical parameters as the Peclet number and the initial pH of the soil are obtained. The obtained graphs show similar values in the magnitude of the change of pH predicted by previous models although a greater acidified volume is predicted as consequence of the increase of root density of the radical system.