CHANGE OF HUMUS STATUS IN CASES OF INTENSIVE CULTIVATED SOIL

To obtain objective data on the changes in the humus status of agrogray soil under the influence of various methods of intensive agriculture, a long - term (1990-2014) field experiment was conducted in the conditions of the Baikal forest-steppe. It was revealed that regardless of the usage practice of arable land (continuous fallow, grain - fallow and grain - row crop rotations), the humus content decreased. Its losses during fallowing and the studied crop rotations were correspondingly 21 and 15% of the initial content. The transformation trend of the system of humus substances in all the variants of the experiment was associated with a decrease in the carbon content in the labile (mobile fractions) and increase in the stable pool (immobile fractions). The humus depletion by the labile components with a decrease in its total content indicates the ‘latent' degradation of the studied soil.