Inorganic Reactions of Manganese in Soils

Abstract

Manganese participates in numerous and diverse reactions in soils, including oxidation and reduction (redox), ion exchange, specific adsorption, and solubility equilibria. The distribution of Mn between solution and solid phases is intimately related to the pH, redox conditions, and the characteristics of ligands and surfaces. Manganese(II) is the predominant form found in solution and in association with exchange sites on soil surfaces, while Mn(III) and Mn(IV) are found predominately in a variety of oxide-rich solid phases. The emphasis of this chapter is on the solution and surface reactions of Mn2+ and the Mn oxides, including reactions associated with fertilizer additions. Chapters 4 and 5 provide greater emphasis on redox processes and cycles in soils, but the effects of redox on mineral solubility relationships and on several surface reactions are covered here.