The change of soil density in the crop rotation of oil crops under different systems of primary tillage

The systems of primary tillage (intensive, allope-lagic, minimum and surface) in a crop rotation of oil crops (sunflower, castor-oil plant, soybean, winter and spring rapeseed) were studied during 1971-2011 in a VNIIMK stationary experiment in 4 rotations of ten-field grain-tilled crop rotation. Long-term application of minimum tillage for oil crops instead of annual plowing during 8-9 years didn’t result in excessive soil consolidation and wasn’t followed by significant soil consolidation of plow layer during the next years. However, under all systems of primary tillage there was an increase of a layer density of 10-30 cm (by 0.07 g/cm 3) to 1.35 g/cm 3 which is the maximum accepted value for the most crops.