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Predicting Exchangeable Sodium Ratios in Irrigated Tropical Vertisols
Author(s) -
Sinanuwong S.,
ElSwaify S. A.
Publication year - 1974
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/sssaj1974.03615995003800050015x
Subject(s) - vertisol , sodium adsorption ratio , chemistry , soil water , dilution , sodium , adsorption , salinity , cation exchange capacity , mineralogy , soil science , analytical chemistry (journal) , environmental chemistry , geology , thermodynamics , agronomy , physics , oceanography , organic chemistry , drip irrigation , biology , irrigation
Batch equilibrium studies were used to investigate Nadivalent exchange and to derive Gapon constants for three Hawaii Vertisols. Obtained regression coefficient values indicated that a linear relationship exists between exchangeable sodium ratios (ESR) and sodium adsorption ratios (SAR) for tropical Vertisols. ESR values obtained for two of the soils were slightly lower than the values predicted by Bower's equation (3) and higher than those predicted by the U.S. Salinity Laboratory's equation (11). ESR values obtained for the third soil were lower than those predicted by either equation. Generally, the higher preferences of surface than of subsurface horizons for Na was confirmed. Prevailing electrolyte concentration levels were found more important than any other experimental variable in affecting the precision of ESR estimates for a given SAR. Although ESR values were generally higher at 0.1 N than at 0.01 N , the valence‐dilution effect was reversed for the surface horizon of one Vertisol during Mg‐Na exchange. While little difference was noted between Ca‐Na and Mg‐Na exchange in one of the soils, in the other two significantly smaller ESR values were obtained for the first than for the second reaction. An unexpected type of hysteresis effect was noted, whereby divalent‐soils exhibited greater preference for Na than did Na‐soils. Possible reasons for this effect are discussed.