Hazelnut Combine Development

View the project final report

Commodities

• Nuts: hazelnuts

Practices

• Crop Production: mechanical harvesting

For this SARE project, a self-propelled, over-the-row hazelnut harvester was designed and has been largely fabricated.  The machine uses a pair of rotary shakers to dislodge hazelnut clusters from plants.  These clusters fall onto a collection platform and then into augers on each side of the machine.  The augers move the clusters to the rear of the machine where they are drawn by vacuum to a chamber on the top of the machine.  An auger in this chamber moves the clusters to a threshing mechanism (a.k.a. a green cluster husker) that frees the in-shell nuts from their husks.  Upon discharge from the thresher, a winnowing fan and a rotary drum sorter separate the in-shell nuts from their husks and other debris.  The in-shell nuts are then moved to a storage bin on the machine.  Given that this harvester combines reaping, threshing and winnowing operations, it is referred to as a hazelnut combine.

The original goal of this project was to develop a pull-type combine; however, after some initial design work, it became apparent that such a combine would have some major shortcomings.  A decision was then made to instead develop a self-propelled combine.  This decision added to the overall complexity of the project, significantly extending the time needed for both design and fabrication.  This in turn made it impossible to complete the combine and then test it within the originally-proposed project time frame.

The combine has some unique characteristics that enable it to effectively handle a variety of plant sizes and structure, as well as orchard terrain.  The picking tunnel is relatively large, and the height of each rotary shaker is hydraulically adjustable. The latter enables the shakers to be optimally located with respect to the plant canopy.  The combine has two rear wheels and a single front wheel that provides a very tight turning radius.  Lift cylinders on each wheel enable the machine to be raised 30 inches, and individual control of these cylinders allows the operator to level the machine during operation.  Overall machine length and width are 22 feet and12 feet, respectively.  Transport height is 10.5 feet, which (in combination with out-to-out rear wheel width) enables the machine to be transported on a flat bed trailer with a standard width of 8.5 feet and deck height 3 feet or less.  In harvest mode, the minimum clear height of the picking tunnel in front of the shakers is 12.5 feet, and can be increased to 15 feet with the wheel lift cylinders.  Considerable effort went into minimizing overall machine weight to minimize compaction, rutting, and other damage to the orchard floor, and to enable transport with lighter, and less expensive equipment.

It is important to recognize that this project is an applied research project, with the ultimate goal of developing a more sustainable method for harvesting hazelnuts. Currently, the vast majority of the world’s hazelnuts are collected only after they have fully ripened and fallen to the orchard floor. In the Willamette Valley of Oregon—where approximately 99 percent of U.S. hazelnuts are produced—nuts on the orchard floor are windrowed and collected using specialized equipment. To support this practice, orchard floors are typically raked, tilled, and press-rolled prior to nut drop in order to create a flat, bare surface free of rodent holes. These prepared surfaces are highly susceptible to wind and water erosion and are largely devoid of biodiversity. Nuts resting on the orchard floor are in direct contact with soil moisture and various contaminants and are therefore more likely to be lost to mold, wildlife, and other pests. Bins of nuts collected from the orchard floor are also more likely to contain stones, animal feces, and other unwanted materials. Washing these nuts increases post-harvest processing costs and can contribute to the spread of harmful pathogens. Largely because of these concerns (as well has sloping terrain and measureable rainfalls during harvest season), hazelnut growers in the Upper Midwest have chosen to mechanically remove and collect nut clusters from plants before they are fully abscised and fall to the ground. To accomplish this efficiently, effectively, and ecologically, growers are planting hazelnuts in hedgerows while maintaining significant biodiversity on the orchard floor. Central to this entire production system is the development of an over-the-hedgerow hazelnut combine capable of rapidly and efficiently producing bins of in-shell nuts that have not been contaminated through ground contact.

The original objectives of this project where to design, fabricate and test a hazelnut combine, and then broadly share design details and testing results with farmers and potential equipment manufacturers.  However, largely because of the switch from a pull-type to a self-propelled unit, the combine is unlikely to be ready for testing until the summer of 2027.  For this reason, the remainder of this report is focused on design and fabrication details. This is not meant to lessen the importance of testing.  Once machine fabrication is complete, extensive and comprehensive field testing will be required to answer numerous questions related to its design and operation. Most importantly, this testing will determine optimal harvest speeds and the percentage of crop harvested as a function of plant variety, size, maturity, structure, pruning, and other management practices. In addition, any irreversible damage to plants and the orchard floor must be evaluated, and both the degree of nut damage and the volume of unwanted debris in the nut bin must be recorded. At a more fundamental level, testing is necessary to assess how each unit operation—including shaking, cluster collection and transport, threshing, and cleaning—performs individually and in combination. Field testing will also evaluate overall machine stability and maneuverability across varying terrain and weather conditions; ergonomic considerations related to operator safety, comfort, and visibility during both day and night operation; the structural integrity of the frame and components; the adequacy of hydraulic pumps, motors, cylinders, and cooling systems; the sufficiency of the engine and drivetrain; the speed and responsiveness of hydraulic controls; and the ease, safety, and cost of over-the-road transport.