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Hydrogen and Calcium Ion Ratios in Dilute Equilibrium Solutions as Related to Cation Saturation
Author(s) -
Webster G. R.,
Harward M. E.
Publication year - 1959
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/sssaj1959.03615995002300060024x
Subject(s) - saturation (graph theory) , chemistry , soil water , vermiculite , kaolinite , chlorite , clay minerals , calcium , mineralogy , analytical chemistry (journal) , ion , inorganic chemistry , environmental chemistry , soil science , geology , quartz , paleontology , mathematics , organic chemistry , combinatorics
Soil samples were collected from field experiments so as to obtain a range in (Ca + Mg) saturation and pH for each soil type. The effects of equilibrating media were studied by comparing water and 0.01 M CaCl 2 , each at 0.0003 and 0.0108 atm. partial pressure of CO 2 . Linear relationships were found for pH − ½ p(Ca + Mg) in the equilibrium solution vs. (Ca + Mg) saturation of the samples. Correlation coefficients ranged from 0.84 to 0.94 and were higher in every case than for pH of suspension vs. (Ca + Mg) saturation. The highest correlation was obtained with samples equilibrated in H 2 O and at the higher partial pressure of CO 2 . It was also noted that some soils equilibrated in water at the higher level of CO 2 released Ca and Mg to solution more readily than other soils at the same degree of cation saturation. The fact that samples equilibrated in H 2 O revealed differences between soils in amounts of Ca + Mg released, whereas, samples equilibrated in CaCl 2 solutions did not, was regarded as an important advantage for studying ion ratios in H 2 O solutions. Grouping of soils on the basis of their clay mineral content did not materially improve the correlations. The clay minerals in the soils studied were fairly similar, mostly vermiculite, kaolinite and chlorite, probably in differing amounts.