Magnetic Susceptibility of Chernozems of Siberia

A comparative study was carried out for the first time of the magnetic susceptibility for two subtypes of Siberian chernozems, depending on the characteristics of their geographical distribution, formation of properties, and composition. A total of 12 soil profilespit were studied, nine of which are represented by ordinary and three by leached long-term frozen and permafrost chernozems of Western, Middle, and Eastern Siberia. The volumetric magnetic susceptibility (χ) of the studied chernozems was determined using a specially developed and patented, precise, express, and reliable method using a small-sized KM-7 cappameter from the Czech manufacturer StatisGeo. The specific magnetic susceptibility (χ) was calculated using the formula: χ = χ/ρ, where ρ is soil density, kg/m3. It is shown that the studied chernozems of Siberia are formed in contrasting landscape and climatic conditions of soil formation and composition of soil-forming rocks, leading to significant differences in their magnetic susceptibility, manifested both at the subtype level and at the level of individual pedons. Close positive correlations have been established between the specific magnetic susceptibility of these chernozems and the content of humus, coarse and medium sand fractions, as well as of fine sand, and negative ones for pHн2o, easily soluble salts, and CaCO3. While ordinary chernozems in the European part of Russia are characterized by a typically accumulative magnetic profile, those in Siberia, subject to prolonged freezing and on permafrost, are characterized by a regressive-accumulative profile. At the same time, ordinary permafrost chernozems differ from long-term frozen soils in their statistically significant values of specific magnetic susceptibility, which, in our opinion, is associated with the processes of cryogenic ferruginization.