Chestnut Harvest Burr Management

Chestnut Harvest Burr Management

Summary

WORK ACTIVITIES

As described within our grant application, “Our project is to manage burrs from separation of the nuts to removal from the orchard. We will redesign and rebuild a currently owned almond harvester to ensure burr separation after picking them off the ground. Burrs will be blown onto a specially designed trailer using the harvester blower. Nuts will be conveyed to a bin on the same trailer. The burr holding section of the trailer, a burr box, will allow removal and disposal of the burrs outside the orchard.” In our timeline, we proposed, “Oct. 2014 to Jan. 2015; Experiment with the design and efficiency of the burr management and harvest equipment. Collect harvested burr and nut, volume and weight data.”

During this past year we created a PERT chart plan for scheduling the redesign and rebuild an older Weiss McNair harvester. The harvester’s end use is not to simply harvest chestnuts but to separate the burrs from the nuts in order that the burrs can be removed from the orchard. All design activities were complete by July 31.

Rebuilding the harvester involved shortening the machine, replacing the conveyor belt, creating a vacuum chamber within the harvester for burr removal, increasing air speed from a blower to expel the burrs, and combining the air flow from two blowers to create a venturi effect of higher air speed.

We also had a burr box and trailer fabricated to collect the burrs. A frame on the rear of the machine was built to hold a pallet bin for catching the separated nuts. The burr box was built with a drop bottom which allows for easy removal and disposal of the burrs outside the orchard.

The Michigan Nut Growers Association (MNGA) Fall Meeting was hosted at our farm on a rainy Saturday on October 4, 2014 with the intention of demonstrating our burr harvesting machine. The meeting was attended by 35 growers. Due to the weather, we were not able to perform an orchard demonstration but did show the machine, attached to a tractor, and running in place.

We spent $6,140 on redesign and fabrication of the modified harvester plus $100 on the MNGA meeting.

RESULTS

The wet cool summer weather complicated our project. The first nuts were harvested on October 8, well after the October 1 expected date. A trial run of the harvester was conducted on October 1, the beginning of unfilled burr drop. Very few mature nuts were on the ground. Although most of the mature nuts dropped the week of October 13-18, a significant number were harvested around October 22.

The cool wet weather also produced a significant increase of the number of mature nuts dropping without releasing from their burr.

First we learned that burr management is still the major concern. Duds, empty burrs, and burs with nuts must be removed from the orchard to efficiently harvest the nuts. Our hand labor workers were very unhappy when required to contend with burrs that had not been removed.

We learned that nuts and burrs can be separated effectively using air separation techniques. The air speeds needed to separate the burs are 12 meter/sec to separate empty burrs and 14 meter/sec to separate burrs with nuts. A consistent harvester air speed adds to the efficiency. Our machine is not yet doing this efficiently.

To get efficient air speeds at both separation points within the harvester, a large duct was designed on the top of the harvester. That duct scraped many branches and knocked nuts from the tree prematurely. We learned that an efficient machine will require a smaller profile than current design.

We also learned that an efficient method to separate mature nuts from their unopened burrs may be needed, either as part of the harvester or as an additional part of the processing line. Leaving mature nuts in their burrs and disposing of them with the burrs may not be cost effective.

Being unable to get duds out of the orchard before harvest, having an extended harvest season with many mature nuts in their burrs, and having a machine with too large a profile for the orchard, meant that we were unable to use the harvester as anticipated and were unable to collect harvested burr and nut, volume and weight data.

WORK PLAN FOR 2015

The first 2015 step, again, is to create a timeline plan for modifying the machine. The nut bin and burr box/trailer successfully worked as planned requiring no changes. However, modifications are necessary to reduce the physical height of the equipment and increase the fan speed of the second blower. The existing machine’s height is unacceptable causing immature nuts to be knocked off trees and physical tree limb damage. Large burrs and wet burrs were not completely separated from the nuts. Additional wind speed should correct this.

Additionally, the fan speed needs to be made adjustable to compensate for wet or dry burrs. Once set, the air speed needs to be consistent. This will probably require a hydraulic motor system.

After the modifications are made, tests will be conducted during the 2015 harvest season with data on burr and nut, volume and weight collected. Additional demonstrations will be scheduled.

• Burr management PERT chart for redesign and rebuild of Weiss McNair harvester

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