K:\17-4\BALASHOV.VP

A b s t r a c t. The objectives of our studies were to: 1) estimate the effects of compaction of sandy loam and clayey loam soils on growth parameters of winter wheat plants, 2) evaluate the resilience capacity of the root system for the water-stable aggregation of compacted soils. Soil samples at field capacity were placed into pots with an initial bulk density of 1.2 Mg m -3 and compacted with ground contact pressures of 51, 103 and 154 kPa using a hydraulic compressor. Five plants in each pot were allowed to grow for 7 weeks till the boot stage. Results showed that wheat roots increased the water-stable aggregation of both soils in respect to treatments without plants. The dry weight of the roots was less affected by the increasing bulk density of the clayey loam soil than it was by the sandy loam. The resilience capacity of the root system for the water-stable aggregation in the sandy loam and clayey loam soils decreased only after applying a ground contact pressure of 154 kPa. The roots affected differently the distribution of separate size fractions of water-stable aggregates of 0.25-0.5 to 5.66-9.51 mm in both soils. K e y w o r d s