Ferromanganese concretionary neoformations: A review

Based on the original and published data, the results of studying the properties, composition, genesis, and information significance of ferromanganese concretions in the soils of the taiga, broadleaved forest, and forest-steppe zones are summarized. The role of these neoformations in the field and analytical diagnostics of soils is analyzed. Some regularities of the changes in the chemical composition of ferromanganese concretions as related to the degree of the soil bogging or profile drainage were revealed. Under the regular increase in hydromorphism of the soils, the content of iron increases and that of manganese decreases. In this case, the ratio between the iron and manganese contents extracted by 1 N H 2 SO 4 also increases. This ratio was named the coefficient of bogging. This coefficient is used in practice to assess the expediency of drainage of mineral soils. The participation of ferromanganic concretions in the accumulation of macro- and micro-elements is shown. A model experiment has revealed that ferromanganese nodules can be formed during a rather short time (1–2 years).