K. Trendafilov, G. Tihanov, D. Kadiev
1Department of Mechanical Engineering, Faculty of Techniques and Technologies, Trakia University, 8600 Yambol, Bulgaria
2Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 14 September 2024; accepted for publication 29 January 2025)

Abstract. The publication discusses a study on the granulometric composition of the soil during cultivation with a combined machine consisting of a share plough and an active soil chopper. It has been established that in order to achieve good cultivation of the soil with the combined machine, in which there is a higher proportion of soil particles with sizes up to 50 mm in the surface layer of the soil at a depth of up to 10 cm, the controllable factors should have the following values: operating speed 1.389 m/s; height of the axis of the soil chopper from the bottom of the furrow – 0.36 m; frequency of rotation of the shaft of the soil chopper – 220 – 280 min-1; distance of the axis of the soil chopper from the tip of the plough body share – 0.75 m for the layer with a depth of 10-20 cm, for the surface layer with a depth of 0-10 cm the influence of this factor is not unambiguous and is subject to additional research. It is proven that when ploughing with a soil chopper, soil aggregates with dimensions below 50 mm are 89.4% and 84%, respectively, in the layers with a depth of 0-10 cm and 10-20 cm. The obtained results confirm the hypothesis that the developed combined machine can be used for pre-sowing soil cultivation.