Evaluation of an autonomous GPS-based system for intra-row weed control by assessing the tilled area

An automatic tillage system for inter- and intra-row weed control based on real-time kinematic GPS navigation and control has been used to address the problem of mechanically removing weeds within rows of precision seeded crops. The system comprised a side-shifting frame with an attached tine-rotor (cycloid hoe) with eight sigmoid-shaped, vertically directed tines. The individual tines can be released for individual rotation in order to avoid collision with geo-referenced crop plants. The system navigated with reference to pre-defined waypoints for tillage parallel to crop rows and around individual crop plants. The system evaluation was based on quantification of treated areas for uprooting and burial and the corresponding prediction of weed control efficiencies. A single pass of an 80 mm wide row band provided tillage of 30–49% of the intra-row area, with highest coverage at a speed of 0.32 m s⁻¹ and at even plant spacing. A double pass, once on each side of the row in opposite directions, provided higher soil disturbance intensity and resulted in tillage of 31–58% of the intra-row area with highest coverage at a speed of 0.32 m s⁻¹. The intra-row weed control effect was predicted to be up to 20% for a single pass and up to 29% for a 2-way pass treatment both at the white thread to the two-leaf stage of weeds. The result of the prediction is of crucial importance for the considerations of tool designs at the current conceptual stage of the system.