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MECHANISMS OF FORMATION OF SODIUM CARBONATE IN SOILS
Author(s) -
WHITTIG L. D.,
JANITZKY P.
Publication year - 1963
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1963.tb00956.x
Subject(s) - soil water , carbonate , bicarbonate , chemistry , environmental chemistry , sulfate , sulfide , sodium , organic matter , sodium bicarbonate , geology , soil science , organic chemistry
Summary Mechanisms of formation and accumulation of Na 2 CO 3 have been studied in a graded sequence of salt‐affected soils of the Sacramento Valley, California. The soils are confined within a drainageway which is inundated during winter with flood waters containing relatively low concentrations of neutral sodium, calcium, and magnesium salts. Heavy inundations and high water tables within the basin lead to microbiological reduction of sulfate and ferric iron. The resulting sulfide is held within the soil as FeS whereas the CO 2 released by biological oxidation of abundant organic matter forms bicarbonate. Lateral and upward migration of bicarbonate‐charged water from the drainageway basin to soils nearer the basin rim results in yearly increases in concentration of soluble salts within these soils. Ca(HCO 3 ) 2 and Mg(HCO 3 ) 2 migrate from the zones of maximum CO 2 production and precipitate as carbonates. NaHCO 3 continues to move, along with the capillary water, and accumulates in the rim soils. As water evaporates or is used by growing plants, loss of CO 2 from the NaHCO 3 occurs, resulting in the formation of Na 2 CO 3 . The high Na 2 CO 3 concentration at these rim positions has resulted in removal of divalent bases from the exchange complex, an equivalent increase in exchangeable sodium, and high pH.