ИСТИНА

The use of heavy agricultural machinery, climate changes and other factors cause mechanical deformation of the soil humus horisons which often aren't found out by traditional methods of soil physics. Rheological approaches allow to estimate inter-partial interactions, micromechanical behavior and, hence, to receive the information l of soil structure deformations and its consequences. The humus horizons of typical chernozem (Kursk region) of the arable field, an adjoining forest belt, chernozems under fallow during 40 years and under natural oak forest have been investigated. Rotational viscosimeter with the cylindrical measuring device was used to study rheological behavior of soil samples. The preliminary capillary humidified samples were used. Complete rheological curves (direct and return branches) have been received. Dependences of viscosity of soil on speed of shear in half-logarithmic scale have been constructed. The received dependences looked like power-low behavior. The investigated samples on viscosity value have arranged in a following decreasing order: oak forest – a virgin soil – a forest belt - fallow – an agricultural arable land. The strongest inter-partial interactions have remained in soil under oak wood and on a virgin soil. The carbon content in the investigated number of soils decreases in the same order, as well as viscosity. Possibly, the content and quality of organic matter of chernozem soils is the main factor of soil structure stability, but constant plowing and agricultural use have led to the accelerated mineralization of organic substances and accordingly to degradation of soil structure.