FIXATION OF POTASSIUM IN RELATION TO EXCHANGE CAPACITY OF SOILS

Abstract

More K is fixed from alcoholic than from water soln. Anions of highly ionized acids reduce and anions of weakly ionized acids increase the fixation of K. Organic matter in the soil medium decreases the fixation of K by diverting it to the exchange position in the organic matter. A decrease in exchange capacity due to removal of iron and perhaps other members of the R2O3 group results in a lowering of the K fixed. However, the decrease is not proportional to the decrease in exchange capacity. The blocking of K in the fixation process is possible by introducing large organic molecules, such as brucine. The effect of Ca conc. on the fixation of K is related to the pH of the system and not to the additions of lime per se.