Articles

The evidence and factors of the formation of compact horizons in haplic chernozems are discussed. They include a complicated combination of agronomical consolidation, modern solonetzization, and residual alkalinity. It is shown that the combination of physicomechanical and chemical properties (high content of physical clay and clay fraction, low portion of aggregate openness and high interaggregate porosity, the presence of exchangeable sodium in the soil adsorbing complex, alkaline reaction (pH 8.3), mobility of the clay-humus fraction, etc.) favor the formation of overcompacted plow and subplow horizons and their dynamic stability independently of regular mechanical cultivation.

The features of the distribution of the stable isotope composition of carbon and nitrogen for saprotrophic and mycorrhizal macromycetes growing on an oligotrophic peatland were characterized for the first time. The molecular identification of the free-growing mycelium of mycorrhizal fungi detected the presence of both ecto- and arbuscular mycorrhizal fungi. Stable isotope composition of fruiting bodies and mycelium of mycorrhizal fungi of peatland differed fractionally. The fruiting bodies of saprotrophic fungi growing on the surface of the moss cover were enriched in ¹³С, but not in ¹⁵N, compared to their main substrate, sphagnum. Differences in the isotopic composition of functionally different parts of the fruiting bodies of macromycetes (hymenophores and stipes) were minor. The mycelium of mycorrhizal fungi of the peatland is enriched in ¹⁵N by 1,4 to 9,5 ‰ compared to the tissues of host plants. These values noticeably exceeds similar values, that were previously shown for forest ecosystems.