EFFECT OF FERTILIZERS AND BLACK FALLOW ON SMALL-PARTICLE FRACTION OF CHERNOZEM SOILS

The heterogeneous system of the soil and its mineral components are altered by prolonged application of mineral and organic fertilizers and by constant black fallow condition. These procedures result in a decrease in the strength of bonding between mineral components of micron size, the breakup of mica-smectite structures with a high percentage of smectite packets, and accelerated disintegration of clastic minerals. Application of manure prevents mobilization of the clay fraction and the breakup of the smectite component. Increased yields after black fallow result from accelerated weathering of minerals, especially the layered clay minerals.