Transformation of clay-sized minerals in soils exposed to prolonged regular alternation of redox conditions

Abstract The direction of the transformation of Fe-bearing minerals under harshly changing redox conditions is still under debate. Some studies suggest preferential accumulation of weakly crystalline Fe oxides while other studies showed that repeated redox cycles favour the presence of crystalline phases. Since characterized by distinct redox cycles, paddy soils are ideal for studying redox-related transformations of Fe oxides and Fe-bearing clay minerals. We analysed changes in the Fe mineral assemblage upon long-term reduction–oxidation cycles along a chronosequence of 100, 700, and 2000-year-old paddy soils developed on comparable parent material relative to two non-irrigated counterpart…