Acidic Properties of Soils as Influenced by Their Mineralogical Characteristics
1965
Page, A. L. | Peterson, F. F. | Martin, J. P.
A number of soils with their clays predominantly composed of biotite, hydrobiotite, and vermiculite or predominantly montmorillonite were treated with 0.1n HCl, washed free of excess acid, and then air-dried. This acid treatment produced soils whose exchange complex was largely saturated with some form of aluminum. When 1n KCl aqueous suspensions of acid-treated montmorillonitic soils were equilibrated with varying amounts of 0.1n NaOH, the reaction of the base with the Al-soil was essentially complete in 30 min. Contrarily, when suspensions of the acid-treated vermiculitic soils were similarly equilibrated, the reaction was less than 50% complete at the end of 30 min. The base-titratable acidities of the acid-treated montmorillonitic soils were essentially the same as their 1n KCl-extractable acidities. The acid-treated vermiculitic soils, on the other hand, had base-titratable acidities that were 1.7 to 2.7 times greater than the acidities extractable with KCl. Results presented suggest that difficultly replaceable Al-polymers form more readily in the interlayer spaces of vermiculitic soils than they do in the interlayer spaces of montmorillonitic soils.
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