The structure dynamics of leached chernozem under long-term application of different systems of primary tillage in oil crops rotation

In 1971-2011, the systems of primary tillage (intensive, plowing on different depth, minimum and surface) in oil crops rotation (sunflower, castor, soybean, winter and spring rapeseed) were studied in a VNIIMK stationary experiment in 4 rotations of ten-field grain-tilled crop rotation. Long-term application of minimum and surface tillage for oil crops instead of annual plowing didn’t result in deterioration of soil structure and contributed to some content decrease of clay fraction in the upper layer (0-10 cm). Dispersion of leached chernozem as a result of mechanic tillage is taking place only to a certain limit. If tillage is carried out on time in the conditions of optimum moisture then the content of silt doesn’t exceed 8-10 % from overall mass even under the long-term replacement of minimum and surface plowing with the tillage. The tendency toward increase of water stability of lower layers structure of plowing layer was observed as a result of replacement of plowing with shallow plowing in crop rotation system.