Characterization of indigenous glauconitic sandstone for its potassium-supplying potential by chemical, biological, and electroultrafiltration methods

Chemical and biological extraction and electroultrafiltration (EUF) desorpt ion of potassium (K) from four size-fractions of indigenous glauconitic san dstone were studied to assess its K-supplying potential. Potassium extracte d by chemical extractants showed an increase in K release with decrease in size of the particle. At high acid strength and high temperature and voltag e in EUF, the K release was substantially greater, particularly from fine-s ized fractions. About 7 to 9% of the total K in the glauconite was released in 12 consecutive boiling 1M nitric acid (HNO3) extractions. Kinetic studi es indicated that the release of K from glauconite was a diffusion-controll ed phenomenon. Pearlmillet biomass, K concentration in plant tissue, and to tal K uptake were significantly increased by the addition of fractions of d ecreasing size. Thus, prospects exist for use of indigenous glauconitic san dstone as a source of K.