Infrared Study of Oxidized and Reduced Nontronite and Ca-K Competition in the Interlayer

Huo, Dongfang

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Description

Title

Infrared Study of Oxidized and Reduced Nontronite and Ca-K Competition in the Interlayer

Author(s)

Huo, Dongfang

Issue Date

1997

Doctoral Committee Chair(s)

Stucki, Joseph W.

Department of Study

Agronomy

Discipline

Agronomy

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Geochemistry

Language

eng

Abstract

Ca and K selectivity in the interlamaller space of the unaltered, reduced, and reoxidized ferruginous smectite (SWa-1) was studied. The results of this study can be applied to estimate fertilizer K availability in the production field. Cation exchange method was used in this study. In the unaltered clay mineral, Ca displayed a strong preference over K. This preference, however, was reversed when the clay was chemically reduced with sodium dithionite. When the reduced clay was reoxidized, Ca, again, displayed a preference over K, but the ratio of Ca to K was not restored to the original extent. The selectivity of cations in the interlamaller space of SWa-1 also depended on the ratio of Ca to K in the exchanger solution, and on the total concentration of the exchanger solution. Those results indicate that the conventional estimation of the available K based solely on the mineral composition of the soil-clay fraction is insufficient. The redox state of soil-clay and the competing cations (Ca and Mg most common) also play very important roles in controlling K availability.

Graduation Semester

1997

Type of Resource

text

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