ABSTRACT
Threat of global ecological crisis dictates necessity of studying of laws of chemical elements circulations in natural and anthropogenic disturbed ecosystems. The climate change problem is connected with damage of a global carbon cycle. Data of two-year observation over seasonal dynamics of the content and reserves of the total and labile carbon of humus substances of an arable variant of podzolic soils of a southern taiga are presented. It is revealed that arable soils contain insignificant amount of humus carbon; its content and reserves essentially vary not only on depth of a soil profile but also during a growth season. The general scheme of formation of an organic part of aboveground cover inseparably linked with biological circulation of matters and soil formation for which the most essential unit is a decomposition of dead organic rests accompanied by simultaneously going processes: accumulation of a primary organic material, decomposition, microbial synthesis, humification, and mineralization.
