POTASSIUM-SUPPLYING POWER OF EIGHT ALABAMA SOILS

Abstract

Eight agriculturally important soils representing 4 physiographic regions and a wide range in chem. and mineralogical composition were investigated from the standpoint of the transitions of K that occur between the exchangeable and nonexchangeable forms. Considerable variation exists between the soils studied with respect to their rate of release of K from mineral forms. There was no apparent relationship between the capacity of the soils to release K from nonexchangeable forms and either the total K content or its distribution among the particle size separates. There was no relationship between K release and the original exchangeable K absorbed by 5 crops grown in the greenhouse. Under some conditions field-applied K may accumulate in significant quantities even in coarse-textured soils. There is a wide range in the tenacity with which applied K is retained by the different soils against soln. Of the soils included in this study, those containing montmorillonite released fixed K more readily than did the kaolinitic soils.