IMPORTANCE OF ROOT SYSTEMS FOR SOIL FORMATION IN DRY STEPPES

The effect of tree roots on initially forest-free light chestnut soils of Volgograd district Has been assessed, based on observations under experimental forest shelter belts organized by N.A. Kachinskiy more th an 40 years ago. Major changes in soils caused by tree roots consist i n increased soil water permeability and decreased soil density. The fo rmer contributes to desalinization of soil ingredients of the ''light chestnut complexes'' due to elevated soil moisture content in winter a nd spring. The increase in soil moisture content is accompanied by an increase in humus; the contribution of roots is not, however, evident, as there is no organic-substances increment within the rhizosphere. S oil volumes that are reclaimed (inhabited) by roots should be specifie d separately from those that are in direct contact with roots.