EFFECT OF TYPE OF CLAY MINERAL ON THE UPTAKE OF ZINC AND POTASSIUM BY BARLEY ROOTS

Abstract

Zn and K ions adsorbed on clay particles are readily utilized by excised barley roots. Under comparable exptl. conditions, the roots tend to remove more cations from bentonite sols than from kaolinite sols. This is especially true for low conc. of cations. At higher conc. no difference was found. The same behavior was observed with suspensions of Yolo silt loam and Aiken clay. The former contains montmorillonitic clay, the latter, kaolinitic clay. These findings cannot be explained by the current CO2 theory and soil soln. concepts, for hydrolysis, carbonic acid, and NaNO3 bring about a greater release of cations from kaolinite than from bentonite. Some additional factor, not yet fully evaluated, but associated with the nature of the colloidal clay, comes into play.