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Dispersion of Pure Clay Minerals as Influenced by Calcium/Magnesium Ratios, Sodium Adsorption Ratio, and Electrical Conductivity
Author(s) -
He Yangbo,
DeSutter Tom M.,
Clay David E.
Publication year - 2013
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/sssaj2013.05.0206n
Subject(s) - kaolinite , dispersion (optics) , illite , montmorillonite , clay minerals , adsorption , sodium adsorption ratio , magnesium , chemistry , mineralogy , soil water , sodium , electrical resistivity and conductivity , analytical chemistry (journal) , materials science , soil science , geology , environmental chemistry , physics , agronomy , organic chemistry , quantum mechanics , optics , drip irrigation , irrigation , biology
Sodium concentration and the soil solution Ca/Mg ratio may influence soil dispersion and water movement. This study investigated the impact of electrical conductivity (EC), Na adsorption ratio (SAR), and Ca/Mg ratios on dispersion thresholds of pure clay minerals (montmorillonite, illite, and kaolinite). Replicated laboratory studies were conducted where the impact of SAR (1, 5, 12, or 24), EC (0–16 dS m −1 ), and specific Ca/Mg ratios on clay dispersion was determined. The results showed that Ca/Mg ratios did not influence clay dispersion of montmorillonite and kaolinite. For illite at a SAR of 12, however, dispersion was reduced by reducing the Ca/Mg ratio from 1/0, 2/1, and 1/2 to 0/1. Dispersion thresholds were <6 dS m −1 across all clays. At a SAR of 12, dispersion occurred for EC < 2 dS m −1 . Kaolinite exhibited little, if any, dispersion. These results indicate that in soils having little or no organic C (i.e., subsoils), Mg does not influence dispersion thresholds and that dispersion risks can be reduced by adopting practices that maintain the EC > 2 dS m −1 .