Abstract. The inv estigations were carried out in the Perm Krai to determine the tillage method, providing a favourable structural and aggregate state of the soil and the formation of high yields. We studied three tillage methods: ploughing by PLN-4-35 at 20–22 cm; subsurface loosening by KPE-3.8 at 16–18 cm, followed by disking by BDT-3 at 8–10 cm; subsurface loosening by KPE-3.8 at 16–18 cm. Treatments were carried out in autumn and spring. In total, the experiment design included 6 variants in 4-fold replication. The soil of the experimental plot was sod-podzolic, slightly cultured, heavy loamy. Its initial structural composition corresponded to a poor and unsatisfactory state. The tillage contributed to the change in the structural and aggregate composition of the soil. In the variants with the autumn tillage, the highest content of valuable structural aggregates with a size of 0.25–10.00 mm was noted with an optimal content of macro-aggregates (less than 25%). In general, the structural condition in the variants with autumn tillage was characterized as excellent, and in spring it was good. The tillage method influenced in the greatest degree the content of waterresistant meso-aggregates in the soil; the time of tillage influenced the content of water-resistant micro-aggregates. As a criterion for assessing the structural state, we used the entropy index and its change from the use of tillage methods. Entropy was calculated by the content of structural aggregates for all variants of the experiment. Its increment was determined by the difference of entropies: 1 – between the initial soil and the variants of the experiment; 2 – between processing options and traditional autumn ploughing. All tillage methods influenced the structural state of the soil in the layers of 0–10 cm, 10–20 cm and 20–30 cm. Spring tillage had a smaller impact on the structural state in the layers of 0–10 cm and 10–20 cm, than autumn processing. In terms of the entropy increment, it can be concluded that the rate of change of the structural and aggregate composition in the variants with spring treatments was lower than during autumn ploughing, despite the greater influence of spring tillage than standard autumn ploughing. An economically advantageous method of tillage in the cultivation of oat on sod-podzolic soil in the Non-Chernozem zone is the subsurface loosening by KPE-3.8 at 16–18 cm.