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 Hanway, J. J. Articles by Stanford, G. Search for Related Content PubMed Articles by Hanway, J. J. Articles by Stanford, G. Agricola Articles by Hanway, J. J. Articles by Stanford, G.

Replaceability of Ammonium Fixed in Clay Minerals as Influenced by Ammonium or Potassium in the Extracting Solution¹

ABSTRACT

Fixed NH₄ in vermiculite and bentonite was completely released by distillation in NaOH solutions. Small amounts of K in the solutions, however, blocked this release of NH₄. If the amount of K was in excess of 2 K ions per 100 Na ions, no fixed NH₄ was released from vermiculite. With smaller amounts of K present, the amount of fixed NH₄ released decreased as the K/Na ratio in solution was increased. In an equilibrium NaCl extraction, small amounts of either fixable ion, NH₄ or K, in the solution prevented the release of fixed NH₄. There was no blocking from the NH₄ in the NaOH distillations since it was lost from the alkaline systems. In the salt solutions, NH₄ was more effective than K in blocking the release of fixed NH₄. The blocking effect of a gixen fixable/nonfixable ion ratio in the neutral salt solutions increased as the amount of salt extractant per gram of mineral was increased. This is due to the preferential adsorption of the fixable cations. Higher K/Na ratios were required to block the release of fixed NH₄ in neutral salt solutions than in alkaline solutions. Ten K ions per 100 Na ions in NaCl were not as effective as 2 K ions per 100 Na ions in NaOH. Higher K/Na or NH₄/Na ratios were required to block the release of fixed NH₄ from bentonite than from vermiculite. The NH₄/Na ratio required to completely prevent the release of fixed NH₄ from bentonite by NaCl was 0.04 as compared to 0.02 for vermiculite.

¹ Journal Paper No. J-2868 of the Iowa Agr. Exp. Sta., Ames, Iowa, Project No. 1234, Department of Agronomy. Presented at the North Central Branch meeting of the American Society of Agronomy, Ames, Iowa, June 29, 1955.

² Associate Professors and Professor in Soils, respectively.

Received for publication January 9, 1956. Accepted for publication April 11, 1956.