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Retention of Boron by Layer Silicates, Sesquioxides, and Soil Materials: III. Iron‐ and Aluminum‐Coated Layer Silicates and Soil Materials
Author(s) -
Sims J. R.,
Bingham F. T.
Publication year - 1968
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1968.03615995003200030029x
Subject(s) - kaolinite , vermiculite , boron , chemistry , montmorillonite , aluminium , clay minerals , mineral , mineralogy , materials science , composite material , organic chemistry
Boron retention as a function of pH was determined for Fe‐ and Al‐coated layer silicates using a previously described procedure (15). Treating the Na + and K + forms of South Africa vermiculite material with Al 3+ prior to B treatment resulted in equivalent B retention by the two forms. Coating kaolinite with hydroxy iron compounds initially decreased B retention in comparison to uncoated kaolinite. However, as the amount of coating was increased to 4.2% Fe 2 O 3 the amount of B retained was slightly greater than that retained by uncoated kaolinite. Boron retention by the Al‐coated kaolinite and by both Fe‐ and Al‐coated montmorillonite was significantly greater than B retention by the uncoated clays. A single regression line represented B retention as a function of Fe 2 O 3 content for both clays. Boron retention as a function of Al 2 O 3 content for the two coated clays fell on two lines which led to the conclusion that hydroxy Fe and Al compounds in the layer silicates dominate over clay mineral species per se in determining B retention characteristics and that B retention characteristics may be conditioned by clay mineral species. Boron retention at pH 6 by nine soil materials was determined from the difference in the initial and final B concentrations of the saturating solutions. Relationships between B retention and various chemical properties of the soil materials were examined statistically. The highest correlations with B retention were found with free iron oxide content and 1.0 N KCl (pH2) extractable Al 2 O 3 . It was concluded that B retention by these soil materials was in response mainly to their free iron oxide and Al 2 O 3 contents.