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Title:Infrared Study of Oxidized and Reduced Nontronite and Ca-K Competition in the Interlayer
Author(s):Huo, Dongfang
Doctoral Committee Chair(s):Stucki, Joseph W.
Department / Program:Agronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
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.
Issue Date:1997
Description:139 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.
Other Identifier(s):(MiAaPQ)AAI9812635
Date Available in IDEALS:2015-09-28
Date Deposited:1997

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