Pull-Type Hazelnut Combine Development

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2023: $30,000.00
Projected End Date: 01/31/2025
Grant Recipient: Happy Roots Farm
Region: North Central
State: Wisconsin
Project Coordinator:
David Bohnhoff
Happy Roots Farm


  • Nuts: hazelnuts


  • Crop Production: mechanical harvesting

    Proposal summary:

    Over 99% of the hazelnuts produced in the United States are grown as a monoculture crop in the Willamette Valley of Oregon. Nuts in Oregon are allowed to fully ripen and fall to the orchard floor, where they are windrowed and swept up using special equipment. To facilitate this practice, the orchard floor is frequently tilled and press-rolled to maintain a flat, bare surface that's void of rodent holes. These flat surfaces are subject to both wind and water erosion and are completely void of bio-diversity. Harvesting hazels in the Oregon manner is not possible in the Upper Midwest given the sloping topography in much of the area - sloping land that requires maintaining a vegetated orchard floor. To: (1) facilitate harvest on sloping terrains, (2) minimize nut predation by animals, (3) eliminate nut contamination via orchard floor contact, and (4) reduce harvest costs, hazel farmers in the Upper Midwest have opted to mechanically remove and collect hazelnut clusters from plants before they are fully abscised by the plant and fall to the ground. To do this efficiently and effectively (and thus drive more cropland toward a more sustainable perennial cropping alternative) requires equipment specifically designed for hazelnut harvesting.

    Project objectives from proposal:


    For the past decade, a handful of growers in the Upper Midwest have used old over-the-row (a.k.a. straddle) blueberry harvesters to mechanically remove and collect hazelnut clusters from plants. Use of these harvesters, along with research recently conducted at UW-Madison with aronia, olive and blueberry harvesters, has demonstrated that hazelnut clusters can be effectively removed by a variety of mechanical shaking devices. At the same time, use of these harvesters has shown they can't adequately handle tall hazel plants, frequently get plugged by dead branches also shook from the plants, and require low-boy trailers for over-the-road transport.  Additionally, these harvesters only remove and collect hazelnut clusters; they don't remove nuts from the clusters [Note: a hazelnut cluster consists of one or more hazelnuts each surrounded by an involucre (a.k.a. husk)]. Instead, clusters are transported to a facility where they are dried, and the nuts then removed from their clusters using specialized husking equipment. 

    The solution to the current mechanical harvesting shortcomings is to design a harvesting machine specifically for hazelnuts that is easily transportable.  In addition to removing clusters from plants, this harvester would also contain a threshing mechanism (a.k.a. a green cluster husker) for freeing nuts from their husks, as well as a system for separating out the nuts (from husks and other debris) and transporting them to a storage bin on the machine.  Given that this machine would COMBINE reaping, threshing and winnowing operations, it is herein refereed to as a hazelnut COMBINE.

    In addition to a green cluster husker and nut cleaning system, the proposed combine would contain a low-cost collection platform that eliminates “stick plugging” issues, and a unique frame with adjustable shaker mechanisms that (1) enable the harvest of taller plants and (2) facilitate long-distance, over-the-road transport without reliance on a low-boy trailer.

    The money secured from this grant would be solely used to pay for a portion of the raw steel and components needed to build the combine.  Additional material/supplies, travel costs, and all labor for the design, fabrication, assembly and testing of the combine will be donated/covered by team members.  The UW-Madison BSE shop will be relied on for parts fabrication when needed (see letter of support).

    It is important to note that team members Bohnhoff, Bashaw and Osterhaus are agricultural engineers, each with a long history of successful product development.  Each has not only designed several different pieces of agricultural equipment, but each (without any outside help and often on a shoe string budget) has used their machining, sheet metal fabrication and welding skills to build the machines.  It is an awareness of, and an appreciation for each other’s engineering talents and fabrication skills, combined with their farming experiences and mutual interest in sustainable crop production (which they share with Ronsheim), that has brought them together over the past few years.  It is an association that will enable attainment of the following objectives at minimal cost.


    1. Fully detail a hazelnut combine harvester using CAD software.  Produce a complete set of shop drawings for machine fabrication. (January – April, 2023)
    2. Fabricate the structural frame, collection platform, shaking mechanisms, cluster transport system and hydraulic power system.  Assemble into a “cluster harvest machine” (combine sans thresher and cleaning systems) (April- August, 2023)
    3. Field test cluster harvest machine, and in separate trials, test an improved green cluster husker and cleaning system (August-October, 2023).
    4. Use knowledge gained from field tests to fabricate and assemble complete hazelnut combine (November, 2023-April, 2024)
    5. Push technology transfer and publicly demonstrate combine (May-December, 2024).


    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.