BAR‐TAL, A., Volcani Center, Bet Dagan, 50250, Israel
BAR‐YOSEF, B., Volcani Center, Bet Dagan, 50250, Israel
CHEN, Y., Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel

Zinc movement in soils is influenced by soil pH, the presence of organic chelators, the total quantity of Zn in the soil and by root exudates. The effect of these factors on Zn uptake by a single plant root was simulated mathematically by Bar‐Yosef et al. (1980). The objective of this paper was to validate this simulation model and evaluate the relative importance of soil chemical properties, the stability of Zn complexes and the soil pH in determining Zn transport in soil and absorption by plant roots. To avoid problems of soil and plant variability, an artificial root, namely a ceramic tube through which solutions of known composition flowed, was used. The soil was a montmorillonite‐sand mixture of known Zn adsorption characteristics. The model satisfactorily described the decline in net Zn influx into the root (Fzn as soil pH increased or as total Zn in soil (Qzn) decreased, and also described Fzn, as a function of time. Addition of fulvic acid (FA) to the soil decreased Fzn. The decreased uptake rate stemmed from the lower permeability of the root to the large Zn‐FA molecule. When the pH of the solution that flowed inside the tube was decreased from 5.0 to 2.0, thus generating a greater efflux of H+ by the roots, Fzn, increased four‐to six fold, depending on the time. The model satisfactorily described the decline in Fzn, as the clay fraction in the soil increased, while maintaining the same quantity of Zn per volume of soil. Copyright © 1991, Wiley Blackwell. All rights reserved