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

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agronomy

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Huo, Dongfang

Contributors dc:contributor

• Stucki, Joseph W.

• Geochemistry

Language dc:language

eng

Identifier

(MiAaPQ)AAI9812635

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87667