ABSTRACT
Ion uptake from the soil by plant roots entails several biological, chemical, and physical processes taking place concomitantly in a variable and changing environment. The processes themselves are not only complex and often nonlinear, but they also interact with and affect each other. Therefore, simulation of such these processes is complicated, and even today one fails to describe them in detail. Computer models are intended for one of two purposes. On one hand, they serve as research tools, summarizing the scientific understanding of the processes in question. On the other hand, they can serve as tools for decision makers, in agriculture (fertilization management, water consumption), environmental protection (contamination by fertilizers, decomposition of residues), and ecology (e.g., cycling of nutrient in an ecosystem, limiting growth factors). Models are tools for description of reality and prediction of outcomes of various changes. Thus, they may vary according to their purpose, treating in detail some parts of the soil-plantatmosphere system, whereas simplifying other components the detailed description of which seems to be less crucial. This is usually done because the more complex a model is, the more room it has for errors and deviations from the actual behavior of the real case. Yet, a model is useless unless it is verified by actual data of the real system. In the following the basic structure of the different types of models will be presented (cf. Silberbush, 1996), but the emphasis is on recent approaches to modeling of nutrient uptake from the soil, and recent development in modeling.
