Postharvest Resource Survey

We are seeking input regarding a research and education project with the goal of consolidating postharvest information in a single set of resources.

Our proposed project aims to consolidate existing knowledge, best practices, and new developments in postharvest equipment, infrastructure, and buildings into a web-based handbook, workshop curriculum / educational materials and recorded videos.

Click here or on the picture to take the survey! 

This survey is voluntary and anonymous. Summarized and anonymized results will be included in a grant project proposal and also on our website ( Please direct any questions to Chris Callahan,, 802-447-7582 x256.

The survey should take an average of 3 minutes to complete.

Thanks for your help.

Produce Safety Record-keeping Requirements & Tools: Presentation

This presentation discusses several different options for record keeping and tracking of produce safety documents and farm logs on an online interface. This was recorded at the Great Lakes Expo in Grand Rapids Michigan December 2017 and given by Chris Callahan UVM Extension, Ag Engineering.

DewRight Debut: From Product to Patent

This video is an episode from Across the Fence! It holds an interview with Judy Simpson as well as a description of the product.

The video below highlights the 9min segment specifically talking about the DewRight.

Read the write up from Vermont Business Magazine here.

Read the press release from UVM’s University Communications here.

Vermont Farmers Food Center Heats with Biomass

Rob Steingress (VFFC), Bill Kretzer (12 Gauge Electric) and Greg Cox (VFFC) perform final inspections before the initial firing of the boiler.
Rob Steingress (VFFC), Bill Kretzer (12 Gauge Electric) and Greg Cox (VFFC) perform final inspections before the initial firing of the boiler.

UVM Extension and others supported the recent installation of a 341,200 BTU/hr (output) multi-fuel biomass boiler at the Vermont Farmers Food Center (VFFC) in Rutland, VT.  The boiler heats the Farmer’s Hall building with the capability to use several alternative fuels to displace propane. The boiler was fueled primarily on wood pellets but was also able to feed and burn grass biomass pucks. This demonstration project carried a cost premium when compared to a typical propane heater installation.  That premium is paid back over time due to recurring fuel cost savings. A simple payback period of 2.2 to 8.0 years is feasible against a cost premium of $51,255 for the boiler depending on the fuel used and the amount of use. For more details about the project and the economic performance please see the report.

Continue reading Vermont Farmers Food Center Heats with Biomass

Grass and “Ag Biomass” Competitive with Wood Chips

Chris Davis (Meach Cove Trust) prepares the boiler and combustion testing equipment for a trial run of the new fuel.
Chris Davis (Meach Cove Trust) prepares the boiler and combustion testing equipment for a trial run of the new fuel.

Recent testing at the Meach Cove Trust has demonstrated strong economic and technical feasibility of grass-based biomass combustion fuels.  The use of solid, densified, cellulosic biomass fuels has been well demonstrated with wood pellets in residential and light commercial systems and wood chips in larger, often centralized systems.  The Grass Energy Partnership of the Vermont Bioenergy Initiative has been exploring an alternative form of fuel; grasses densified in a specially developed processor to take the form of 1.5”-2.0” round cylindrical pucks.  Grass fuels may be produced on otherwise marginal agricultural land, sometimes in perennial production and even in buffer strips offering environmental benefit.  Additionally, fuel can be made by densifying agricultural residue or biomass harvested from idle pasture or fields.  We have referred to this fuel as “Ag Biomass”. The testing summarized in this report has demonstrated the technical and economic feasibility of such fuels.

Continue reading Grass and “Ag Biomass” Competitive with Wood Chips

Final Report – Increasing Supply and Quality of Local Storage Vegetables

We recently completed a project aimed at improving the ability of Vermont vegetable farms to store crops such as beets, carrots, parsnips, potatoes, onions, squash and sweet potatoes, all of which have unmet demand in late winter when local supplies run out.

Beets can be stored in bulk bins for months at the right conditions.
Beets can be stored in bulk bins for months at the right conditions.

The physiology of these crops allows them to be stored for many months after harvest if specific storage conditions are met. However, several distinct sets of conditions are optimal for different groups of crops, and achieving each condition requires careful control and monitoring of temperature and relative humidity in storage. Currently, Vermont’s commercial vegetable farms rarely achieve the optimal conditions due to lack of sufficiently separated storage compartments, and lack of modern environmental monitoring and control equipment.

Installing a remote monitoring system to keep track of temperature and humidity of a storage facility.
Installing a remote monitoring system to keep track of temperature and humidity of a storage facility.

This project installed environmental monitoring equipment to improve storage conditions and ultimately the quality of 1,736 tons of winter storage crops at 9 farms throughout Vermont .  The cumulative market value of these storage crops produced during the 2012-2014 growing seasons was $3.5 million.   Improved storage monitoring led to better control of storage conditions, in part through automated notification to farmers when abnormal conditions were occurring. This allowed for prompt correction of problems such as open doors and failing or inoperative cooling equipment. Losses of storage crops (cull rates) were reduced from ~15% to ~5% of stored volume. Sixty-six  energy efficiency measures were also implemented at 5 of these farms, saving a total of 40,269 kWh of electricity and $5,800 annually.  The systems deployed have increased the confidence of growers to expand their winter storage of Vermont-grown vegetables, leading to an increased supply of local produce outside of the traditional growing and marketing season.

You can download the complete report here.

DIY Auto-fill Humidifier

I recently built a humidifier I think others might find useful.  This could be useful for cheese aging, meat curing, and storage of winter crops all of which require maintaining specific temperature and humidity. The details are available on the Tool Wiki at FarmHack.  Take a look, and let me know if you find ways to improve it or if you have any questions.  As part of this project I also developed this handy spreadsheet that calculates relative humidity based on dry-bulb and wet-bulb temperature and/or calculates wet-bulb temperature based on dry-bulb temperature and relative humidity.  The spreadsheet also helps you tailor the humidifier design to your needs by estimating humidification capacity in gallons of water evaporated per 24 hours.

The idea was to turn a 5 gallon bucket into a high capacity (4 gal/day), automatic fill humidifier. The bucket serves as a reservoir for the water and also as a mounting platform for the parts required to operate the humidifier. Water heated to a know temperature will transfer a predictable amount of water vapor to an air stream of a known temperature and humidity (wet bulb temperature). We use this property to develop a highly controlled humidifier using a temperature control to sense water temperature and control the heater, tank deicer for heat, and a CPU fan for air flow. We also add a toilet fill valve to the assembly to allow for automatic fill of the humidifier.


2013 UVM Mobile Hops Harvester Summary

On the Road Again
On the road with the UVM Mobile Hops Harvester.

The UVM Mobile Hops Harvester visited six hop yards this year, harvesting approximately 400 dry pounds of hops, over a 4 week period plus harvesting the UVM Extension NW Crops and Soils Team’s research hop yard. This harvester, developed as a result of a Northeast Hops Alliance, UVM Extension, VT Agency of Ag Food and Markets, and MA Department of Agriculture sponsored project, aims to provide proof of concept of a mobile hops harvester in support of the re-emerging hop industry in the Northeast US.

The reintroduction of hops to the northeast requires scale-appropriate harvest and processing equipment. At the start of this project there was no feasible mechanized harvest options for a 1-2 acre hop producer. Handpicking is the most wide-spread current practice which is labor intense and time consuming leading to expense and quality impact due to delayed harvest.

As a result of this project, cooperative use of a single, mobile harvester has been demonstrated and logistics for this operation are being continually improved. The harvester has a demonstrated capacity of 60-120 bines per hour compared to 1 bine per hour per person for manual picking. This rate enables the harvest of a 1 acre yard within 8 hours resulting in optimal harvest timing and improved quality. Assuming a harvest team of 4 people in either case, this translates to a harvest labor cost savings of 97% or $3,120 per acre at $15 per hour wage (approximately $2 per lb of dried hops (10-20% of retail price)).

Kris Anderson of Addison Hop Yard and Chris Callahan of UVM Extension.
Kris Anderson of Addison Hop Farm and Chris Callahan of UVM Extension. (Addison, VT)

“The hop harvester significantly sped up harvesting.  With the size of the bines this year, some may not have been harvested at all without it’s use.  Knowing the UVM harvester is available helps me plan for hopyard expansion over time.  Without a large harvester, such a UVM’s, expansion would not be practical.”, notes Kris Anderson of Addison Hop Farm in Addison, VT.

Trevor Lewis of Mad Mountain Hop Farm in Berlin, VT concurs, “Absolutely amazing! My harvest time went from 5 days to 5 hours! Though I am unsure of expansion at this time, this machine makes it possible to expand beyond a half acre which really isn’t an option without a harvester.”

Trevor Lewis and the Mad Mountain Hop Farm crew.
Trevor Lewis and the Mad Mountain Hop Farm crew. (Berlin, VT)

This mobile, trailer-based mechanized hop-harvester was developed and documented as an open-source design for others to replicate and adapt to their needs.  The design was the result of a collaborative design effort involving growers, brewers, agronomists, fabricators and engineers. Additionally, 255 people have downloaded the plans for the machine and 5 others have built harvesters at least partially informed by this work. This harvester pulls a complete bine (central bine/vine, leaves and cones) through a section of stripping fingers that separate the cones and leaves from the bine.  The cones and leaves are conveyed to a secondary sorting section with rolling dribble belts against which the leaves lie flat while the cones roll backward down the belts. In this way the machine takes a loaded bine and produces two output streams of cones and leaves.

We’ve been reasonably pleased with capacity and efficiency of the machine.  There is still room for improvement, and we plan to install chutes and fences over the winter to better contain all matter within the machine, improve separation and, thus, net yield. We also had two bearings fail this harvest season and will likely upgrade them to heavier duty bearing housings.

The entire machine is placed on an 18 foot equipment trailer for ease of transport.  This year, the machine traveled approximately 3,400 miles visiting some yards multiple times as different varieties matured. Each year, the harvester travels further afield for an outreach demonstration.  This year we traveled to Westfield, Maine (Aroostook County) to Aroostook Hops to help with their harvest and to give them some experience with the harvester.

Kathleen, Krista, Marie and Jason Johnson of Aroostook Hops in Westfield, ME with their first bin of cones off the machine.
Kathleen, Krista, Marie and Jason Johnston of Aroostook Hops (Westfield, ME) with their first bin of cones off the machine.

“Having the UVM mobile hops harvester had a HUGE impact on our success this year.  We had a hops picking party the previous weekend (Labor Day) with many volunteers handpicking hops (we estimate about 60 people passed through that weekend) and we got about 40% of our crop harvested,” says Krista Johnston, ” We had two articles in the local press about us and lots of interest was generated, so we couldn’t have done better on “many hands”, but without the harvester here the following weekend we could not have gotten all the hops in this season by handpicking alone.”

Krista and her husband, Jason are thinking ahead to building a harvester of their own.

“We plan to fabricate a version of the mobile machine, so being able to use it ourselves and have our fabricators come out and operate it (for about 2 hours of time x two men) was absolutely invaluable to us.  We had thought that “mobile” was less important to us and that we would build stationary with electric motors, but seeing how convenient it was to move around different locations made us reconsider that.  Also, we recently expanded (last year) 3 acres so can’t even think about getting bigger any time too soon, but having the capacity to harvest at the rate that the harvester can accomplish will remove that as a limiting factor when we catch our breath and consider future operations.  We do plan to contract our harvester to other growers, and had thought we’d have bines come to us, but mobile is looking attractive.”

Others have replicated and adapted the UVM design to their needs for the 2013 harvest season.

Nick Aleria and the Yellow Dog Hop Yard crew (Cabot, VT).
Nick Aleria and the Yellow Dog Hop Yard crew (Cabot, VT).

“We wouldn’t have been able to build our harvester without the knowledge and research from the UVM machine,” says Dean Heltemes of Lunatic Fringe Farms in Wisconsin. “I’m sure this picker will create a lot of buzz around our co-op. We might have the opportunity to do some harvesting for a farm a couple hours from here. The more hours we can get on this thing, the better off we will be for next year.” Video of Lunatic Fringe Farms’ harvester can be viewed on YouTube.

And so it goes, each year more hours are accrued on the harvester, more variations are built and we all continue to learn and improve together using this open source design. Plans for the machine can be downloaded from the UVM Hops Project Wiki at Chris Callahan can be reached by email or phone at 802-773-3349.