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Sodium‐Calcium Exchange Behavior in Organic Soils
Author(s) -
Naylor D. V.,
Overstreet Roy
Publication year - 1969
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/sssaj1969.03615995003300060016x
Subject(s) - chemistry , soil water , ion exchange , calcium , cation exchange capacity , leaching (pedology) , sodium , selectivity , adsorption , inorganic chemistry , san joaquin , environmental chemistry , ion , soil science , geology , organic chemistry , catalysis
The exchange complex of two organic soils from the Sacramento‐San Joaquin delta of California was easily saturated with calcium. However, the Ca 2+ of the calcium‐saturated soil was difficult to replace with Na + even when the calcium‐saturated soils were leached with 1 N NaCl. Exchange of the Ca 2+ by Na + was found to be reasonably stoichiometric and complete after extensive leaching of the calcium‐saturated soils with the 1 N NaCl solution. A large fraction of the adsorbed Ca 2+ was extremely difficult to replace with Na + when the soils were leached with large volumes of 0.01 N NaCl. The Ca‐Na ion‐exchange isotherms of the soils were determined through the use of Vanselow's and Gapon's ion‐exchange equations. Vanselow's ion‐exchange “constant” indicated an increased selectivity for Ca 2+ over Na + as the amount of exchangeable Na + increased while Gapon's equation yielded a constant selectivity throughout the isotherms. Both equations suggested that the soils exhibit a very large selectivity for Ca 2+ over Na + , especially as the amount of exchangeable sodium becomes appreciable.