Automated intelligent rotor tine cultivation and punch planting to improve the selectivity of mechanical intra-row weed control

There is much emphasis on technical aspects related to sensor or mapping techniques, which enable so-called intelligent cultivators to target the intra-row spaces within crop rows. This study investigates (i) an expected advantage of an intelligent rotor tine cultivator (the cycloid hoe) in terms of crop-weed selectivity and (ii) an expected synergistic effect between punch planting and post-emergence weed harrowing in terms of improved crop-weed selectivity. Selectivity is defined as the relationship between weed control and associated crop density decline one week after cultivation, and punch planting is a sowing technique where holes are created in the ground with a minimum of soil disturbance and seeds are inserted into them, without soil disturbance outside the holes. Two experiments were carried out with the cycloid hoe in organic sugar beets. The rotation tines were guided by RTK-GPS relative to geo-referenced sugar beets, and tines were moved into the row when there was enough space between crop plants to cultivate, and kept outside, when they were predicted to strike a crop plant. The selectivity of the cycloid hoe was tested against two machine variants without intelligent guidance: the rotor tine cultivator in a locked mode, where tines rotate within the crop row without taking crop plants into consideration, and an ordinary flex tine weed harrow. The experiments showed no differences between the three machine variants in terms of selectivity. Five experiments with punch planting in sugar beets and carrots showed no synergistic effects between plant establishment procedures and selectivity of post-emergence weed harrowing. Even if punch planting and automated intelligent rotor tine cultivation were not combined, the results indicate that there is no reason to believe that a combination contributes significantly to the solution of the main problem in mechanical intra-row weed control in direct sown crops, low selectivity, which still remains a major challenge. Future studies on precision intra-row cultivation should focus on cutting implements instead of tine implements which manly works through soil burial.