Development of Small-Scale Storage Facilities for Winter Storage of Fresh Produce

Final Report for LNC11-329

Project Type: Research and Education
Funds awarded in 2011: $108,829.00
Projected End Date: 12/31/2015
Region: North Central
State: Wisconsin
Project Coordinator:
Scott Sanford
University of Wisconsin-Madison
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Project Information

Summary:

This project developed an 84 page technical bulletin entitled “On-Farm Cold Storage of Fall-Harvested Fruit and Vegetable Crops: Planning, Design and Operation”. This comprehensive bulletin includes information on determining space requirements, types of storage facilities, number of cold storage rooms needed, environmental conditions required for different crops, construction materials and techniques, refrigeration systems, humidification equipment and material handling for stored crops. The outreach of this project made presentations in Wisconsin, Illinois, Missouri, Indiana, Iowa, New Jersey, South Dakota and MOSES Organic conference with about 926 people attending the 16 presentations at fifteen conferences. In addition a resource website has been set up to provide ongoing information to growers on the subject of cold storage (http://fyi.uwex.edu/cropstorage/). Growers are encouraged to submit questions for consideration in a “Frequently Asked Question” section.

An ambient-air cooling controller has been developed that can control the use of ambient air cooling in multiple cold storage rooms. A publication on how to build your own unit is in the publication process and should be available summer 2016. A link will be provided on the crop storage website to the publication. A small low-cost humidifier and humidistat was testing and work satisfactorily. Humidification is the one environmental parameter that is not well controlled in most on-farm cold storage facilities. The humidifier was shown to growers at many meetings so they could get an idea of how simple these units are.

Several decision making tools were developed: A tool to estimate the energy cost to operate a cold storage facility, one to estimate the cost of construction of a conventionally framed cooler and an economic analysis tool to help determine if you grow and store a crop, if you can be profitable.

Project Objectives:

  • Develop plans and construction details for 3 different basic storage facilities types that can be modified (enlarged or reduced in size) based on a grower’s needs and resources: These three basic types are: in-ground (earth contact on a minimum of 3 sides), new above ground construction, and storage rooms install into existing buildings (such as old dairy barns).

  • Develop plans for an effective low-cost environmental control using commercially available components to control temperature, humidity and take advantage of outside air for temperature modification.

  • Test different methods for humidifying small storage facilities and develop recommendations for small-scale winter storage facilities. Methods under consideration for testing include residential room humidifiers, small evaporative cooling pads, misting, and commercially-available humidifiers.

  • Develop extension publication(s) that will cover design and management of a cold storage facility. This will include full plans for sample structures that would be available as a free PDF download from the University of Wisconsin Extension Publication web site.

  • Develop and deliver workshops and webinar presentations to disseminate the information to educators and growers throughout the North Central region. Our goal would be to do 6 to 10 workshops and 4 to 8 webinars. Some of the workshops would be in cooperation with a grower that has built a facility or with a regional meeting such as the Midwest Organic Farming Conference. An average of thirty people per workshop or webinar is expected.

  • Develop a spreadsheet decision tool to aid growers in determining if winter storage crops will be economical for their operation. It will be posted on the national eXtension website.

  • Develop web pages on crop storage facilities for the national eXtension website. Links will be provided for publications, spreadsheet tools, educational presentations from workshops and webinars.

  • Work with grower/cooperators to test plans, designs and environmental controls. We hope to find growers to test all three designs. Because of the time between the writing of this grant, the start of funding and the availability of finished plans is about 2 years, it was premature to identify growers now. If a grower currently has an interest in building a storage facility, they are likely not going to wait 2 years for our project to develop plans. With the interest in locally supplied food, we don’t think we will have any trouble finding interested parties to test our plans.

  • Provide assistance to growers who are developing their own facilities. We will aid growers who have been through a workshop or webinar to develop a farmstead plan and modify plans to fit their individual needs.

Cooperators

Click linked name(s) to expand
  • John Hendrickson
  • Scott Sanford

Research

Research results and discussion:

This project developed an 84 page technical bulletin entitled “On-Farm Cold Storage of Fall-Harvested Fruit and Vegetable Crops: Planning, Design and Operation”. This comprehensive bulletin includes information on determining space requirements, types of storage facilities, number of cold storage rooms needed, environmental conditions required for different crops, construction materials and techniques, refrigeration systems types and requirements, humidification equipment and material handling for stored crops. This bulletin provides information that will be valuable for the beginning and the experienced grower. Unfortunately, this publication couldn’t be offered for free due to the size of the publication and budget cut but is moderately priced at $19.95. Any serious grower will reap more than $20 in benefits from this publication. There isn’t anything else available that is this comprehensive.

A website has been setup that is dedicated to the storage of vegetables and fruits (http://fyi.uwex.edu/cropstorage/). It contains an extended reference list with links to many of the source materials to compliment the “On-Farm Cold Storage of Fall-Harvested Fruit and Vegetable Crops” publication.

There is an Educational Presentations tab that contains two videos of presentations. One presentation is on the design consideration for a cold storage taking one through the different types of facilities, crop requirements, considerations for building your own facility, layout in conjunction with processing and packaging activities and material handling consideration. The second presentation focuses on what is required to maintain produce quality while it is in storage. The presentation covers field heat removal with precooling, the effect of storage temperature and respiration rates, importance of proper humidity levels, humidification equipment options, the effect the refrigeration evaporator can have on achieving humidity levels, temperature injury (hot and cold), length of storage, temperature control, use of outside air for cooling, air flow in storage, space requirements and economics. The presentations can be accessed at http://fyi.uwex.edu/cropstorage/educational-presentations/

As part of the development of the bulletin, a spreadsheet model has been developed to estimate the energy use in coolers. The tool uses weather data and the growers input on the size, envelop construction, temperatures, loading rates, and amount of produce held in storage to estimate the monthly and annual energy use for refrigeration and heating for the operation of a storage facility. The tool can be access at http://fyi.uwex.edu/cropstorage/energy-use-estimator/

For those people who are considering building their own cold storage room, a spreadsheet was developed to estimate the material needed for a conventionally framed small storage facility. Based on the size of the cooler desired (user input) the spreadsheet will calculate the materials needed for the walls, ceiling and roof (if outdoors). The user can input the local cost of materials to determine the cost of materials for the cold storage room. The program also calculated the typical size of refrigeration unit that would be used based on the cooler dimensions. The tool can be access at http://fyi.uwex.edu/cropstorage/on-site-built-walk-in-coolers/.

An economic analysis tool has also been developed that allow growers to assess the amount of produce needed to cost justify a storage facility for fall harvested produce. Using this tool in combination with the Veggie Compass farm profitability tool will help growers analyze if adding storage crops will be profitable for them. The tool can be access at http://fyi.uwex.edu/cropstorage/economics-of-storing-produce/

Centrifugal humidifiers were found to be the most cost effective small cold storage facilities. There require lower maintenance than misters, are low cost and appear to be reliable. Evaporative cooling pads can be used with bulk storage but few small growers have a dedicated bulk storage facility. Most will use pallet boxes to store larger quantities of produce and then a centrifugal humidifier works best. A small centrifugal humidifier was tested and found to work well for small coolers. The humidifier could be connected to a water supply or could utilize an elevated reservoir (5 gallon pail on a stand) to supply water to the humidifier. There are sizing recommendation in the “On-Farm Cold Storage” publication for humidifier units. Improper humidification is the major factor that was found to be missing in many grower facilities. In facilities that did have humidifiers, they often lacked a humidistat to control the humidity levels and instead used a time clock to intermittently add moisture to the air. This can lead to disease issues because it can create wet surfaces on the produce or wide swings in humidification level. Humidification was stress in all presentations and usually showed the small humidifier so growers could see it. Potential vendors for Humidification equipment can be found at http://fyi.uwex.edu/cropstorage/equipment-vendors/.

An Ambient Air Cooling controller has been developed that uses a low cost programmable logic controller to control dampers, fans, heaters and will activate the refrigeration system if it takes too long to lower the cooler temperature to the set point temperature. The controller is programmed to handle from 1 to 3 storage rooms but can be expanded to handle more if needed. A bulletin detailing the design, damper equipment, fans, software program is in progress and should be published during the summer of 2016. It will also provide design information for a simple system using two temperature controllers to open and close damper and turn on a fan when the outside air temperature is lower that the set point temperature of the cold storage room and the temperature in the room is above the set point.

Outreach activities during the grant period included presentation at:

Stateline Fruit & Vegetable Growers Conference – February 11, 2013 – 30 people

Missouri Beginning Farmers Program – Dec 2, 2013 – ~ 20 people

South Dakota Organic Agriculture Conference – Dec 3, 2013 – 50 people

Wisconsin School for Beginning Market Growers – 1/18 to 1/20/2014 – 40 people

Wisconsin Fresh Market Growers conference – 1/21/2014 – 50 people

Illinois Specialty Crop Conference – 1/9/2014 – 100 people

Great Plains Fruit and Vegetable Growers Conference – 1/10/2014 – 60 people

Indiana Hort Congress – 1/22-23/2014 – 115 people

Iowa Fruit and Vegetable Growers Conference – 1/24/2014 -30 people

MOSES Organic Farming Conference – 3/1/2014 – 270+ room couldn’t hold everyone

WI School for Beginning Market Growers – January 9-11-2015 – 24 people

New Jersey Vegetable Growers Conference – Feb 4, 2015 – 35 people

Stateline Fruit & Vegetable Growers Conference – February 5, 2013 – 25 people

MOSES Organic University Class – Feb 26, 2015 – 55 people

Michael Fields workshop – Feb 19, 2015 – 22 people

Total attendance at presentations: 926 people

We had ten direct contacts for consulting assistance during the grant period. One resulted in a site visit to look at the best place to locate a cold storage room in an old barn, one review plans and made suggestions for the design of an additional cold storage facility. The remaining contact were by phone or email and included vendors for small humidification equipment, the value of an insulated floor, freezer equipment for blackberries, converting a shed into a cooler, using earth tubes to moderate temperatures, Pros and Cons of an below ground versus above ground storage facilities, and design and insulation of a root cellar.

Research conclusions:

During the project we gave presentations to 926+ growers and educators (about double what was predicted) about the types of structures for crop storage structures, refrigeration requirements, environmental controls, material handling, types of storage containers, estimating space requirements, crop storage requirements (temperature, humidity), types of humidification equipment, air flow patterns and requirements, planning traffic flow and selecting the cooler size and door placement to match the storage container size to maximize storage capacity. The presentation covered the states of South Dakota, Wisconsin, Indiana, Illinois, Kansas/Missouri/Nebraska, and Iowa although presentations at MOSES would have included people from many other states.

We helped provide information to ten growers directly to help them with decision making on crop storage projects and provide some beginning farmers information that should help then make fewer mistakes.

A resource website has been developed to provide information on fruit and vegetable crop storage. The site has an extensive reference list that compliments the “On-Farm Cold Storage” publication. It also includes videos and handouts of presentations, tools for calculating energy and construction costs, an economic analysis tool to guide growers in decision making, and an extensive vendor list to save growers time in finding equipment.

An 84-page comprehensive technical bulletin entitled “On-Farm Cold Storage of Fall-Harvested Fruit and Vegetable Crops: Planning, Design and Operation” has been published that should help growers design and operate better cold storage facilities, maintaining high quality produce with lower shrinkage and more profitability. A second bulletin is in progress on how to do Ambient Air Cooling which should be published during the summer of 2016. It will prove design information for a simple system using two temperature controllers and a system using a low cost programmable logic controller that can control multiple rooms, and interface with the refrigeration system if it takes too long to lower the cooler temperature to the set point temperature. It will be posted on the website when available.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

Publications
On-Farm Cold Storage of Fall-Harvested Fruit and Vegetable Crops: Planning, Design and Operation, 2015, Scott Sanford, John Hendrickson, A4105, University of Wisconsin Extension, Madison, WI

Using Ambient Air for cooling cold storage rooms, Scott Sanford, University of Wisconsin Extension, Madison, WI (in-progress expected Summer 2016)

Outreach activities during the grant period included presentation at:

Stateline Fruit & Vegetable Growers Conference – February 11, 2013 – 30 people

Missouri Beginning Farmers Program – Dec 2, 2013 – ~ 20 people

South Dakota Organic Agriculture Conference – Dec 3, 2013 – 50 people

Wisconsin School for Beginning Market Growers – 1/18 to 1/20/2014 – 40 people

Wisconsin Fresh Market Growers conference – 1/21/2014 – 50 people

Illinois Specialty Crop Conference – 1/9/2014 – 100 people

Great Plains Fruit and Vegetable Growers Conference – 1/10/2014 – 60 people

Indiana Hort Congress – 1/22-23/2014 – 115 people

Iowa Fruit and Vegetable Growers Conference – 1/24/2014 -30 people

MOSES Organic Farming Conference – 3/1/2014 – 270+ room couldn’t hold everyone

WI School for Beginning Market Growers – January 9-11-2015 – 24 people

New Jersey Vegetable Growers Conference – Feb 4, 2015 – 35 people

Stateline Fruit & Vegetable Growers Conference – February 5, 2013 – 25 people

MOSES Organic University Class – Feb 26, 2015 – 55 people

Michael Fields workshop – Feb 19, 2015 – 22 people

 

Total attendance at presentations: 926 people

We had ten direct contacts for consulting assistance during the grant period. One resulted in a site visit to look at the best place to locate a cold storage room in an old barn, one review plans and made suggestions for the design of an additional cold storage facility. The remaining contact were by phone or email and included vendors for small humidification equipment, the value of an insulated floor, freezer equipment for blackberries, converting a shed into a cooler, using earth tubes to moderate temperatures, Pros and Cons of an below ground versus above ground storage facilities, and design and insulation of a root cellar.

Project Outcomes

Recommendations:

Areas needing additional study

A survey of growers to determine types of facilities, crop losses/shrinkage, use of humidifiers, storage crops grown, percentage of income derived from storage crops and dollars of sales per volume of cold storage capacity. This information could help determine where future programming needs may be.

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.