Strip-tillage using rotating straight blades: Effect of cutting edge geometry on furrow parameters

• Blades with an inside chamfer or square cutting edge tilled a quality seedbed.
• Outside chamfered blades did not create a furrow, instead produced smeared slots.
• Double-side chamfered blades produced a coarser soil tilth and smeared furrow walls.
• Double-side chamfered blades reduced the furrow centre depth due to bottom ridges.
• Blades with inside chamfered cutting edges are recommended for use in strip-tillage.

Efforts to develop strip-tillage drills for two-wheeled tractors have often used conventional bent rotary blades designed for full disturbance soil tillage which have resulted in poor furrow backfill and smeared furrows. This soil bin study examined the use of rotating straight blades with a range of cutting edge geometries for cutting a 50 mm wide strip-till furrow. Results showed that a set of rotating straight blades can only create a furrow if the blade set exerts sufficient strain onto the soil volume between the blades. The furrow formation was aided when using either inside chamfered or square edged blades. For the same thickness of blades, double-side chamfered blades, due to applying a reduced strain, resulted in an uneven furrow of shallower depth at its centre along with a coarser soil tilth, and additionally produced smeared furrow walls. For the inside chamfered and the square edged cutting edge geometries the furrow backfill was the highest with only 20–26% of loosened soil ending outside the furrow. The outside chamfered blades applied a soil strain outward from the blade set which was not able to produce a furrow and only created two smeared slots in the soil. The study recommends inside chamfered blades be used for strip-tillage, with their optimum thickness related to the targeted furrow width, in order to apply the minimum strain required for achieving a targeted loosening result.