The high organic matter soil (50 -80%) in the Holland Marsh, Ontario, Canada, is ideal for growing root and bulb vegetables but weeds also thrive. There are few registered herbicides and increasing herbicide resistance necessitates hand-weeding, but labor shortages and increased costs increase the interest in alternative methods. The solar-powered FarmDroid FD20 is one option, if adapted to work in vegetables. The FarmDroid was used to seed and weed onions on 2.8 ha of a commercial farm with weed control issues. The robot seeded 21 beds ~800 m long, with 4 single rows in each bed, and seeds 3.4 cm apart within the row, at 225 meters per hour. Seeding took 81 hours. Weeding was done with using a cultivator with metal tines to remove weeds growing between the rows it had seeded, at a speed of 500 m/hr. Weed counts were consistently higher in the robot-weeded than conventional-farmed sections (408 and 186 weeds/m, respectively), largely because of the inability of the robot to weed within the rows. There were no differences in yield. Small scale trials were conducted to compare conventional seeding of four double rows, with single rows as above and clusters of 3 seeds, 12 cm apart in the row. Emergence was 25, 35 and 17 plants/m for single, double and triple cluster seeding, respectively. There were no differences in yield at harvest (73-76 t/ha) but there were significantly more jumbo onions (42%) in those seeded in clusters, compared to the others (9 and 1%). A separate trial assessed seeding accuracy with increased speed. Emergence was highest for onions seeded at 200 m/hr with a significant decrease at speeds of 300 – 500 m/hr. Seeding in clusters shows promise for faster seeding and larger onions. Modifications to improve the configuration of tines for weeding are ongoing.
