Humic Acids of Leached Chernozems of Western Siberia as Influenced by Human Impact

As it is known, the formation of soil humus as well as soil formation is controlled by Dokuchaev’s five soil-forming factors, i.e by climate, vegetation, relief, soil-forming rock and age of the landscape. In connection with fact that the soil has been subjected by heavy human impact during latest one and a half century, it became necessary to take into account the sixth factor, i.e. the anthropogenic one. As for Western Siberia, despite the relatively young farming (mean age of ploughland is about 80-90 years) as compared to other parts of the planet, appreciable humus losses have been progressed from the soils. It is especially observed in the soils of chernozem type widely spread in the forest steppe belt. Along with humus losses, the changes of quality of soil organic matter and structure of its principal constituents are in progress. The paper in question deals with the change of the nature of the most sustainable constituent of soil humus such as humic acids (HA). The study has been performed by the example of leached chernozems (Luvic Chernozem) which are widely spread in Western Siberia and used in long-term dry farming as well as under influence of irrigation