Premium
Effects of Saline Water on the Chemical Properties of Some Tropical Soils
Author(s) -
ElSwaify S. A.,
Swindale L. D.
Publication year - 1970
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/sssaj1970.03615995003400020011x
Subject(s) - chemistry , salinity , soil water , dilution , soil salinity , electrolyte , sodium , cation exchange capacity , environmental chemistry , salt (chemistry) , soil science , geology , thermodynamics , oceanography , physics , organic chemistry , electrode
Surface and subsurface samples of soils representing the Tropical Red Earths and Tropical Red Deserts were equilibrated with unbuffered salt solutions which had the composition of sea water and ranged in concentration between 0.61 N and 0.0061 N . The effects of these treatments on soil pH, the concentration of soil solution, and exchangeable sodium percentages were subsequently characterized. The original acidities of these soils were highly resistant to change. Neither soil showed a tendency to accumulate salts by extraction from percolating solutions. Studies of exchangeable sodium percentages at the various concentration levels supported the valance‐dilution principle. At high salt concentrations, however, the observed affinities of these soils for divalent cations were higher than those predicted by the commonly used US Salinity Laboratory regression equation. To eliminate the possible interference by CaCO 3 in observed ionic equilibria, Na‐Ca exchange studies were conducted on carbonate‐free soil samples. Isoconcentration isotherms were constructed at electrolyte concentrations of 0.01, 0.1, and 1.0 N , compared with isotherms calculated from the US Salinity Laboratory's regression equation. Large discrepancies were observed at 1.0 N concentration, particularly for the lowest soil horizons. For that concentration, it was found that predictions of ionic distribution based on the theory of the diffuse double layer can closely describe Na‐Ca equilibrium when large values of surface charge densities are assumed.