Premium
Gypsum applications to aggregated saline—sodic clay topsoils
Author(s) -
ARMSTRONG A. S. B.,
TANTON T. W.
Publication year - 1992
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.1365-2389.1992.tb00133.x
Subject(s) - phosphogypsum , gypsum , sodic soil , sodium adsorption ratio , dissolution , chemistry , sodium , cation exchange capacity , environmental chemistry , soil water , soil science , mineralogy , geology , agronomy , irrigation , paleontology , organic chemistry , drip irrigation , biology , raw material
SUMMARY Gypsum application was highly efficient as a treatment for reducing amounts of exchangeable sodium and inhibiting clay dispersion in highly structured saline‐sodic clay topsoils. Phosphogypsum, applied to the surfaces of aggregates in soil columns treated with simulated rainfall, was dissolved efficiently by frequent intermittent ‘rainfall’. The calcium released by dissolution displaced sodium on the exchange complex within soil aggregates ranging from 7.5 mm to 45 mm in diameter. Of the applied calcium, 64–74% was transferred to ion exchange sites; however, almost one‐third of this adsorbed calcium displaced exchangeable magnesium. Comparison of three gypsum treatments, phosphogypsum, rock gypsum, and a saturated gypsum solution (representing a top dressing of highly soluble gypsum), showed that the effectiveness of calcium uptake on the exchange complex followed the order: rock gypsum < saturated solution < phosphogypsum, but differences were small. Application of phosphogypsum caused a 90% reduction in the total amount of dispersed clay released in column leachates, and decreased the maximum clay concentration in the effluents by at least 80%, when compared to soils leached without gypsum treatment.