HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by le Roux, F. H. Articles by Coleman, N. T. Search for Related Content PubMed Articles by le Roux, F. H. Articles by Coleman, N. T. Agricola Articles by le Roux, F. H. Articles by Coleman, N. T.

Ion Sorption by Soil Separates and Exchange Equilibria Involving Sodium, Potassium, and Rubidium¹

ABSTRACT

Sodium-potassium exchange reactions were studied with four California soils, utilizing chromatographic and equilibrium procedures. Apparent exchange constants varied with ion saturation and indicated a larger affinity for potassium as its equivalent fraction on exchange sites decreased. This was especially true for soils containing biotite-hydrobiotite-vermiculite in the coarse fractions. Clay and silt-size materials from such a soil were packed into columns, and the sorption-desorption behavior of rubidium was measured using the radioisotope Rb⁸⁶. Irreversible sorption of rubidium with corresponding reductions in cation-exchange capacity was large for silt, intermediate for coarse clay, and negligible for fine clay. Sodium-rubidium exchange isotherms obtained for various size fractions both before and after a portion of the exchange-capacity was "blocked" with Rb or K indicated a quite specific sorption of Rb on certain sites, with "normal" ion-exchange behavior for the remainder of the CEC. X-ray diffraction studies suggested specific sorption of K and Rb by vermiculite and hydrobiotite, irrespective of the Na/K or Na/Rb ratio in saturating solutions. However, even when sites with specific affinity for Rb or K were eliminated, there was significant variation in the apparent exchange constants obtained for different soils. For soil containing vermiculite in the coarse fractions, the specific sorption of radiorubidium may be a conveniently determined guide to potassium fertilizer needs.

¹ Paper No. 1443, University of California Citrus Research Center and Agr. Exp. Sta., Riverside. Presented before the Western Society of Soil Science, Corvallis, Ore., Aug. 28, 1962.

² Graduate assistant and Professor of Soil Science, respectively.

Received for publication December 3, 1962. Accepted for publication March 12, 1963.