Soil Manganese Oxides

Abstract

Manganese oxide minerals in soils are important as a source of the plant nutrient Mn, and for their interactions with other minerals and with other cations (Adams et al., 1969). Also, the oxidative and catalytic properties of manganese oxides influence humus formation (Shindo and Huang, 1984). The presence of manganese oxide minerals in soils can easily be detected by their dark colour, and by the vigorous reaction of these minerals on addition of H2O2. However, relatively little is known about the manganese minerals in soils. Traditionally soil scientists considered manganese (and iron) minerals to be impurities rather than soil components. Therefore, common mineralogical procedures for clay mineral studies involve steps to remove these minerals rather than for their analysis and identification. This oversight, and the inherent difficulties in separation and identification have delayed investigation of these minerals in the soil environment. Also, the structures of all of the manganese oxides are not known, and only recently have some of the tunnel structures been resolved.