The effects of the working speed of a bending subsoiling tool on soil disturbance behaviors and tillage forces

Mechanical subsoiling serves as a highly effective practice for eliminating soil compaction caused by years of consecutive mechanical operations. It also significantly enhances water infiltration and promotes the robust development of crop roots. The bending subsoiling tool (BST), a fundamental implement in subsoiling activities, is employed to optimize soil structure and boost the ability of crops to absorb nutrients and water from the soil. In this study, the discrete element method was utilized to investigate the impacts of the BST's working speed, ranging from 1.5 to 9.5 km/h, on soil disturbance behaviors and tillage forces. The findings revealed that a proper increment in the BST's working speed could elevate a greater amount of moist soils from the deep seed and middle layers into the shallow seed zone, without severely affecting the mixing between the deep layer and other layers. The working speed of the BST had a restricted influence on the lateral soil disturbance range. As the BST's working speed increased from 1.5 to 9.5 km/h, it led to a larger draught force, greater soil surface flatness, a higher soil rupture distance ratio, and a lower soil loosening efficiency. Notably, when the BST's working speed increased from 7.5 to 9.5 km/h, the soil surface flatness increased rapidly. Taking soil layer mixing, soil loosening efficiency, and soil surface flatness into consideration, it is advisable that the BST operate at working speeds lower than 9.5 km/h.