J. Barr, J. Desbiolles, J.M. Fielke, M. Ucgul
No-till seeding operations are typically limited to speeds of 8–9 km h−1 to avoid the excessive soil disturbance caused by straight narrow furrow openers. This study provides a design analysis of a previously identified low disturbance alternative to straight openers – the bentleg opener-in a virtual soil bin constructed with the discrete element method (DEM). DEM modelling results show soil disturbance with bentleg openers is minimised by streamlining the opener, reducing its thickness and maximising its leading chamfer. A curved – rather than angular-transition connecting the side leg to the vertical shank portion further reduces soil disturbance. The bentleg foot initiated soil failure, driving loosening, draught and penetration forces. However, the vertical upheave caused by the foot increases soil throw at shallower settings (<90 mm). Removing the foot reduces the soil upheave height, minimising soil disturbance for shallow (60 mm) and high-speed operation. These characteristics come at the cost of loosening capacity, limiting the use of footless bentlegs to shallower depths (<120 mm). A footless bentleg with a side-leg forward angle greater than 90° offers benefits similar to steep rake angle straight openers, but without the associated penalties of reduced furrow size, increased draught and vertical up forces. Anticipated benefits include the potential to lower field surface roughness improving the harvest-ability of crops and reduce the need for post-seeding rolling operations in stony soils. The results presented increase the understanding of bentleg openers, providing design recommendations for best high-speed performance based on the targeted depth and speed ranges.
Bentleg opener, Discrete Element Method (DEM), Draught force, Furrow opener, No-till seeding, Soil throw