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

2012 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 the first year we have done extensive literature review and designed a low temperature, high humidity cooling unit that could be used with a walk-in cooler as part of a student capstone design project. We’ve held one advisory team meeting via teleconference and have visited three of the advisory team member’s farms plus several other farms to look at their storage facility. A draft of the Storage Facility Design bulletin has been started and continues to progress. We have identified some size appropriate equipment for humidification and an environmental control that may allow the use of outside air cooling. A presentation to approximately 30 growers was made at the Stateline Fruit and Vegetable Growers meeting in Rockford, IL on Feb 11, 2013.

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 didn’t get started until April 2012 due to other commitments which has put the project off the timeline. Thus far we have done an extensive literature review and have begun drafting an extension publication on the planning, design and management of a storage facility. I hope to have a draft completed by the end of June. We have had a teleconference with our advisory committee and I’ve visited three of our advisory board member’s facilities along with several additional facilities to find out what works and look at some different facility designs. We’ve identified a commercially available low cost controller that is designed for greenhouses but will work for temperature control in coolers although we are evaluating whether it can control a system for using outside air for cooling. Many of the facilities visited are using a humidifier design for large bulk storage facilities controlled by a timer instead of a humidistat. As a result they are often over humidifying and creating condensation on crops which can lead to disease and storage issues. We have identified some size appropriate humidifiers for smaller cooler. We have also identified humidistats that can be used to control the humidifier and hope to trial one this summer. During the fall semester, a group of students worked on a project to design low-temperature, high-humidity cooling system for a walk-in cooler using a commercial ice maker. This system should hold humidity and air temperature in the range necessary for holding vegetable such as carrots, beets and cabbage. A prototype is under construction and will be tested this spring. On February 11, 2013 a presentation was made to a group of 30 growers on planning crop storage facilities at the Stateline Fruit and Vegetable Growers meeting in Rockford, IL. We’ve also started to develop a financial tool to help growers determine the economics of adding a storage facility. We are planning to do outreach during December 2013-March 2014 time frame after the bulletin is completed.

Impacts and Contributions/Outcomes

Thirty growers 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