Petromagnetic Properties of Fallow Soils as an Indicator of the Organic-Matter Content

The magnetic properties of chernozem soils, dark and light gray forest soils, and sod-podzolic soils present in the Republic of Tatarstan have been researched and described using the petromagnetism method, coercive spectrometry, and X-ray phase analysis with the purpose of improving the soil monitoring system in relation to fallow and virgin soils. In the course of soil genesis, iron compounds undergo transformations and the magnetic parameters of the soil profile change in comparison with the parent rocks. It can be said that the magnetic profile reflects the pedogenesis processes. A statistically significant relationship between the humus content on the one hand and the susceptibility and intensity of remanent saturation magnetization (J(rs)) on the other hand has been identified. A technique making it possible to separate the contributions of lithogenic and pedogenic magnetic minerals to the saturation remanence (J(rs)) intensity has been developed on the basis of coercive spectrometry. In the studied soils, the pedogenic component primarily consists of the organogenic extracellular constituent of the magnetite-maghemite association, which is the best candidate to proxy in assessments of the humus concentration in soils at various depths with magnetic methods.