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

2013 Annual 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

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


During 2013, work continued on the bulletin which has grown to about 40 pages. I had hope to have a first draft completed by mid-year but we keep finding more information that should be included. Now that the winter meeting season is over, work will resume with the target of getting this to publication by mid-summer. In January, the first of many outreach presentations was made at the Wisconsin School for Beginning Market Growers, Stateline Fruit and Vegetable Growers meeting in Rockford, IL and the Farming for Profit Series. In December, I traveled to the South Dakota Organic Agriculture Conference and did a webinar from the Missouri Beginning Farmers Program. Presentations were also made in Wisconsin, Illinois, Indiana, Missouri and Iowa during January thru March 2014, all well attended with about 800 people attending the eleven presentations and one webinar. A small low-cost humidifier and humidistat was testing in a cold storage over the winter in a grower’s storage unit and worked well. Work is progressing on a controller for using ambient air for cooling using off-the-self controllers, fans and duct zone damper. Some survey work was conducted to evaluate the cost, space requirements, income and income per cubic foot of storage from installing cold storage for extending the marketing season into winter.

Objectives/Performance Targets

1)      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).


2)      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.


3)      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.


4)      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.


5)      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.


6)      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.


7)      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.


8)      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.


9)      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.


The Project is still lagging behind the proposed timeline but good progress is being made. The draft of the crop storage bulletin has grown to about 40 pages and is still being worked on. A section looking at the economics of crop storage is yet to be included and I hope to include some sizing parameters for humidification units after some testing in warm weather during early 2014. As part of the development of the bulletin, a model has been developed to estimate the energy use in coolers and a spreadsheet to estimate the material list for a conventionally framed small storage facility. The winter meeting presentations provided some contact for people who may be willing to review the bulletin for publication.

Data was gathered for a series of financial case studies of farms that do significant winter storage crop sales. This included collecting data on size of the storage units, storage crops grown and marketed, market outlet type, sales volumes, length of time storage crops remain saleable, amount of shrink/spoilage, and labor required to wash, pack and market the storage crops. Several farms were visited to see and photograph their storage facilities. The case study information was compiled, summarized and used in presentations from December 2013 to March 2014.

Outreach activities started in January 2013 with a presentation to the Wisconsin School for Beginning Market Growers (1/18 to 1/20/2014 – 40 people), followed in February with the Stateline Fruit and Vegetable Growers meeting in Rockford, IL ( 2/11/2013 – 30 people) and the Farming for Profit Series (2/18/2014 – 30). The Fall/Winter meeting season started on November 16 with a presentation at the Farm Beginnings workshop ( 15 people) followed by a webinar was done on December 2nd for the Missouri Beginning Farmers Program with about 20 participants and a presentation at the South Dakota Organic Agriculture Conference on December 3rd to about 50 people. Additional presentations were scheduled and made between January and March 2014 at the following meetings (Date – estimated number of attendees): Wisconsin Fresh Market Growers conference (1/21/2014 – 50), Illinois Specialty Crop Conference (1/9/2014 – 100), Great Plains Fruit and Vegetable Growers Conference (1/10/2014 – 50-60), Indiana Hort Congress(1/22-23/2014 – 115), Iowa Fruit and Vegetable Growers Conference(1/24/2014 -30), and the MOSES Organic Farming Conference(3/1/2014 – 270+ room couldn’t hold everyone). In all we had direct contact with about 800 people during 2013 and first quarter of 2014. Some webinars are being planned during early 2014 as well.

Equipment testing is continuing. The cooling unit developed by as Senior Design Project will be ready to test shortly. It uses ice water to provide cooling and humidification and has the advantage of not having to deal with evaporators freezing up as the refrigeration is supplied by ice cube makers located outside the cooler. There is also no risk of freezing crops that are to be stored close to 32F. A size appropriate humidification unit has been purchased and tested in a 24 x 10 x 10 foot cool storage during the winter at a grower’s facility and did an adequate job of maintaining the humidity level. We will be testing it in warmer weather to see if it performs as well. A programmable controller has been purchase to use for providing control for an ambient air cooling system so cold ambient air could be used for cooling instead of using mechanical refrigeration. The PC unit will be programmed and tested with the goal to provide an equipment list and the program so growers can install their own system since there aren’t any systems on the market that would fit a small grower.

Impacts and Contributions/Outcomes

Eight hundred growers and educators have learn 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.


John Hendrickson
Sr. Outreach Specialist
Agricultural Bulletin Building
1535 Observatory Dr
Madison, WI 53706
Office Phone: 6082653704
Scott Sanford
Sr. Outreach Specialist
U of Wisconsin-Madison
460 Henry Mall
Madison, WI 53706
Office Phone: 6082625062