Studies of soil manganese. I. The use of disodium calcium versenate for the extraction of divalent manganese from soils.

Abstract

A new extractant has been developed for the estimation of divalent manganese in soils. The soil is extracted at pH 8.0 with a buffer of calcium and ammonium acetates containing 1 per cent. disodium calcium versenate. The extractant has been shown to give little attack on three precipitated oxides of manganese having respectively the structures of hausmannite, manganite, and manganous manganite. The attack of the extractant on these oxides is not increased in the presence of soils. The new extractant has been found of value for the removal of divalent manganese formed by treatment of soils with reducing agents. Preliminary results with three precipitated oxides indicate that the degree of attack by hydroquinone in the presence of the new extractant at pH 8 reflects the availability of these oxides to oats grown on a fen soil. Some applications of the new reagent are briefly discussed.