Justification of the Structural and Technological Configuration and Design Parameters of a Heavy Disc Harrow for Resource-efficient Soil Tillage

Wide-cut heavy disc harrows are widely used for tillage of perennial grass sod, summer fallow, and stubble fields; however, imported implements commonly used in Kazakhstan are not always sufficiently adapted to local soil and operating conditions, which may re-sult in incomplete sod undercutting, uneven crop residue incorporation, and increased draft resistance. This study aimed to substantiate the configuration, design parameters, and operating conditions of a wide-cut heavy disc harrow for traction class 5–6 tractors under the soil and field conditions of Northern Kazakhstan. Field experiments were conducted to evaluate the effects of disc arrangement, disc angle, operating speed, and support and finishing elements on tillage quality, draft resistance, and energy consump-tion. The developed configuration consisted of a central frame with folding side wings, eight disc sections arranged in two rows, support and transport wheels, an adjustable hitch, and a rear rod roller, with a 7.0 m working width, 660 mm notched discs, and 210 mm disc spacing. Under the investigated conditions, the harrow operated at speeds of up to 11.5 km h⁻¹ and, at disc section angles of 12°, 15°, and 18°, achieved a surface roughness of 3–5 cm, eliminated clods larger than 100 mm, and required 63.8–78.3 MJ ha⁻¹ of specific energy. The results provide experimental evidence for the suitability of the investigated structural configuration and operating parameters for heavy disc harrowing under the field conditions of Northern Kazakhstan.