Analysis of effect of bentleg opener geometry on performance in cohesive soil using the discrete element method

Abstract

Bentleg furrow openers can significantly reduce soil disturbance and reaction forces relative to conventional narrow point openers used in no-tillage farming. The effect of bentleg opener geometry on soil disturbance and reaction forces in a cohesive soil was assessed in a virtual soil bin using the discrete element method. Soil disturbance and reaction forces at an operating depth and a speed of 100 mm and 8 km h −1 , were shown to be minimised by using (1) a shank lateral offset of 70 mm, (2) a side leg bend angle that ensures the elbow, which is the transition between the side leg and vertical shank, is not located below the soil surface, (3) an arched instead of angled elbow, (4) a cutting edge chamfer angle as low as practical, and (5) tine thickness as small as practical. Furrow size was found to be more dependent on shank lateral offset and side leg bend angle than side leg forward angle. Though side leg forward angles >90° reduce particle displacement and will work better in fields with stones and roots, they also considerably increase draught and penetration resistance. A low rake angled foot minimises soil reaction forces and drives soil loosening. Reducing foot height and interaction of the vertical shank with soil particles minimises surface soil displacement. These results have expanded the understanding of bentleg opener mechanics and are in close agreement with those reported for sandy soils. Therefore, similar criteria can be followed to optimise bentleg opener design for different soil types. • Discrete element method predicted bentleg opener geometry effects in Black Vertosol. • Geometries that cause minimum soil disturbance and reaction forces were identified. • Shank lateral offset should be large and arched elbow protrude above soil surface. • Cutting edge chamfer angle and thickness as small as practical are recommended. • Low foot rake angle and foot height reduce soil forces and soil throw, respectively.