Minimising soil disturbance and reaction forces for high speed sowing using bentleg furrow openers

Australian no-till farmers often use narrow point openers to create furrows for seed and fertilizer placement. However, operational speeds are limited due to excessive lateral soil throw reducing furrow backfill and causing interactions between adjacent furrows. This study measured the effects of speed (8, 12 and 16 km h(-1)) on soil disturbance and tillage forces for five different openers, aiming to evaluate suitable options for high speed seeding. Three straight shank openers, 90 (blunt and chamfered face) and 53 rake angles were compared to two bentleg geometries (45 and 95 mm offsets), in a dry silt-loam field soil. The 53 straight opener showed the largest response to speed, reducing furrow backfill and increasing lateral soil throw (from furrow center). The addition of a double sided chamfer reduced lateral soil throw and maintained 100% backfill at 8 km h(-1) but soil disturbance increased at 12 and 16 km h(-1). Both bentleg openers maintained 100% backfill and operated with a lateral soil throw less than half the straight openers at 8 km h(-1) However, the 45 mm offset bentleg opener had more soil throw at speed. This resulted in reduced furrow backfill and increased lateral soil throw at 16 km h(-1) (reaching similar to the straight shank openers). The 95 mm offset bentleg was able to maintain its low soil disturbance characteristics at speeds up to 16 km h(-1) The findings show potential for new opener technology to increase operating speeds of no-till seeding operations by minimising soil disturbance and draft, therefore improving work-rate and timeliness of sowing. (C) 2016 IAgrE. Published by Elsevier Ltd. All rights reserved.