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       Chris Callahan
       1 Scale Ave, Suite 55
       Rutland, VT 05701
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UVM Extension AgEngineering Blog

Rats (and other rodents).

Posted: October 14th, 2016 by Chris Callahan

A few weeks back, two growers and I were standing in the middle of a squash storage room in mid-construction talking about rodent control.  It brought us back to the excellent presentations by Lisa MacDougall and Hank Bissell at 2015’s VVBGA Postharvest Meeting on rats and rodents. That was great stuff. I thought it would be helpful to reach out to the VVBGA listserv and ask folks what is working for them and what isn’t. I asked for both active measures (traps, rodenticides, FSMA compliant cats and ball pythons, etc.) and passive measures (sealing, doors, packing, hardware cloth, novel construction, accepting the loss, selling everything early).  I also dug up some excellent published references that focus on the issue including two with very detailed guidance on passive exclusion using construction methods.  Here’s my summary. Read the rest of this entry »

Pumps and Pipes

Posted: May 14th, 2016 by Chris Callahan

A Taco 007

A Taco 007, shaken not stirred.

“Will the 007 be enough?”  is a common question in early spring as greenhouses around the region fire up and we do our best to keep seed trays and their cargo warm on the still-cool nights.  My mind instantly goes to “which movie?” And then I crash back to earth and realize this is a question about pumps and I am not Q. Read the rest of this entry »

Thermostats for Agriculture

Posted: May 3rd, 2016 by Chris Callahan

I am often asked by growers and processors to recommend a thermostat for greenhouse, cooler, or postharvest process use.  There are many to choose from and their specifications can be confusing. It is important to remember just what a thermostat does. It is essentially no different from the light switch on the wall with one very significant exception.  Instead of depending on a person to switch it from ON to OFF, we use a temperature measurement.  The accuracy of both the temperature setpoint (what you set) and the actual temperature (what the actual condition is) can be critical for production quality and energy efficiency. Read the rest of this entry »

Vermont Farmers Food Center Heats with Biomass

Posted: May 1st, 2016 by Chris Callahan

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.

Read the rest of this entry »

Grass and “Ag Biomass” Competitive with Wood Chips

Posted: May 1st, 2016 by Chris Callahan

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.

Read the rest of this entry »

Finish Surfaces for Produce and Food Areas

Posted: April 29th, 2016 by Chris Callahan

Smooth and cleanable surfaces are an important aspect of areas where produce is washed, packed, stored and processed.  Many farms are investing in renovations and expansions of these areas and are seeking materials to meet this “finish surface” need regardless of specific regulation.  Meanwhile, entrepreneurial food processing companies are often required to incorporate these materials due to regulation.  This is a summary of some of the finish surface materials that are available, their pro’s and con’s and pricing at this time. Read the rest of this entry »

New Crop Storage Planning Tool

Posted: January 21st, 2016 by Chris Callahan

DSCN1606I have been toying with an Excel-based crop storage planning tool for several years.  I finally have it at point where I want to make it available to others and start collecting feedback for improvement.  You can download the tool here, and instructions are available in the tool and at this page.  Enjoy and please be in touch with feedback.


Update on Heating Greenhouses with Biomass

Posted: September 14th, 2015 by Chris Callahan

Get the report.

Get the report.

This project demonstrated the use of biomass heating for greenhouse vegetable production at sites across Vermont. From 2008 through 2015, 25 growers received cost-share funds for greenhouse biomass heating systems. Read the rest of this entry »

Final Report – Increasing Supply and Quality of Local Storage Vegetables

Posted: September 14th, 2015 by Chris Callahan

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.

Doser for Small Scale Vegetable Washing with Sanitizer

Posted: June 16th, 2015 by Chris Callahan

I recently put together a simple doser for manually measuring accurate doses of sanitizer into wash water solutions.  It is really just a homemade burette. The process of mixing a treatment dose of santizer requires metering a specific dose of concentrate into a larger volume of water.  I have also created a calculator to help with that. The UVM Extension Produce Safety Program maintains a great set of resources for general guidance on use of sanitizers including this guide sheet.  It is important to always have a copy of the official product “label” (not necessarily the same thing as the label on the container).  For easy reference, labels for typical sanitizers are linked below. Please check with your supplier to be sure you have the most recent version for the product you are using and the intended application.

There are a number of options available to avoid actually pouring these chemicals when dosing a mix tank.  You can download a summary of these options here.  When pouring them, splashing and spills can occur which are best avoided due to the corrosive and hazardous nature of the chemicals at stored concentrations. Even when using enclosed dispensing options, wear proper personal protective equipment including goggles and resistant gloves in case there are unexpected leaks or spills.

2015-06-14 005

Some of the dispensing options available include:

  • Dosatron – $940-$1000 – Allows for injection of sanitizing chemical directly into the flow stream of water being used in the process.  Measurement is done by adjusting flow ratio similar to a fertigation system.
  • Goat Throat – $299 – GoatThroat 300 Pump with Viton seals. Allows a manual, enclosed pumping with integral valve.   No closed measurement.
  • EnviroSelect Dispensing Pump (BioSafe Safety Value Pack) – $75 – Allows a manual pumping of liquid directly from container without pouring.  No integral valve, and no closed measurement.

When I reviewed these options, I felt there was still a need for something at the lower end of use volume.  Something that would work for 30 to 300 gallon washing batches.  So that is why I put together the assembly that is posted on FarmHack with a parts cost of less than $50 and assembly time of less than 1 hour.  I think it may be helpful. Let me know what you think, and feel free to join in the design discussion on FarmHack.

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