Development and Experimental Analysis of a Pneumatic Based Dibbling Machine for a Forestry Nursery

The rejection rate of tree stock in a forestry nursery can be as high as 35%. This is attributed to plant physiology, poorly trained seasonal workers and unsophisticated equipment. It is estimated that approximately 5% of seedling rejection in the pilot nursery (approximately 220,000 per year) is due to poorly dibbled holes. These holes are typically dibbled using a spiked wheel, which produces crooked and imprecise holes. The poor-quality holes cause bends in the stems, resulting in rejection. This article presents a tractor-drawn mechatronic dibbling machine that can produce precise vertical holes of a specified depth, spacing and diameter. Both hole quality and dibbling efficiency are greatly improved. The machine was tested at a nursery and produced 98% of the holes at the desired angle and 94% at the desired depth. The unwanted stem bends were eliminated with a subsequent reduction in rejects. Furthermore, it was found that worker productivity increased, as they did not have to spend time setting seedlings vertically.