Development of Organic Nutrient Management Recommendations for High Tunnel Raspberry Production

Project Overview

Project Type: Research and Education
Funds awarded in 2012: $49,388.00
Projected End Date: 12/31/2013
Region: North Central
State: Wisconsin
Project Coordinator:
Dr. Rebecca Harbut
University of Wisconsin Madison
Beth Ann Workmaster
University of Wisconsin-Madison


  • Fruits: berries (brambles)


  • Crop Production: organic fertilizers
  • Production Systems: general crop production
  • Soil Management: soil analysis


    The results of this study showed that the HT did indeed increase yields, height, and biomass. The greenhouse effect elicited by the plastic covering of the HT extended the season roughly two weeks both in the spring and fall.   The results of this study also showed a general trend of larger amounts of available nutrients in the HT soil compared to OF soil. Likely as a result of greater rates of nutrient availability and a lack of leaching, soluble salt levels were greater in the HT compared to the OF, although not greater than the raspberry salinity threshold of 1.0 dS/m. It was difficult to determine how much of the nutrient difference was from greater mineralization or decreased leaching in the HT soil compared to OF soil, and how much of the nutrient difference was from the initial nutrient content. The leaf tissue results were mixed, but there was either no difference or only a small difference between the production systems in leaf tissue nutrient concentrations. Those results suggest that canes in the HT were taking up more nutrients, but using it to fuel a larger amount of growth than the OF canes.


    High tunnels are defined as temporary, unheated, plastic-covered structures that provide an intermediate level of climate protection and control.  Crops are planted directly into the soil inside the tunnel which traps solar heat to elevate temperatures a few degrees to extend the season both in the spring and fall.  In addition to extending the season, this production system also offers protection from wind and rain damage, protection from some insects and diseases as well as birds and varmints.  This unique environment presents an opportunity to develop a raspberry production system that requires reduced chemical inputs to manage pests and disease as well as increased control of nutrient management due to reduced leaching of nutrients through exclusion of precipitation.  As this production system is different from field production, best management practices that have been established for field conditions may not apply in a high tunnel environment.  In order to maximize the potential efficiencies and opportunities that high tunnel production presents, it is necessary to understand the opportunities and limitations that occur when utilizing this technology in different regions of the state.  In particular, it is necessary to understand the nutrient management needs in the high tunnel system.  

    To assist in the development of this proposal, a survey was sent out through collaboration with the Wisconsin Berry Growers Association.  The objective of the survey was to determine the level of interest in high tunnel production and to solicit feedback from producers about what they felt were top research priorities for high tunnel fruit production.  Results of the survey indicated that 20% of producers surveyed currently had a high tunnel, but 63% of respondents indicated that they were planning on putting up a high tunnel in the near future.  This interest has been influenced by the NRCS cost-share initiative through the EQIP program to assist in purchasing high tunnel structures in 2010 as many growers indicated they had applied to the EQIP program. 

    The survey also asked growers to identify the top three research priorities for high tunnels.  The top responses were 1) Pest management 2) cultivar selection and 3) nutrient management.  Other areas mentioned include pruning and trellising strategies, irrigation management, marketing and cost of production.  In follow-up phone conversations, growers who are currently utilizing high tunnels indicated that information available from other regions is often not applicable due to the different climatic conditions.  These responses clearly indicate that there is a need to develop a long-term research program to support an emerging high tunnel industry in Wisconsin.


    Project objectives:

    1) Increase growers understanding of nutrient release rates in high tunnels to help growers make decisions about application rates and timing.  

    2) Increased awareness of the importance of tissue testing to determine crop nutrient needs.

    3) Increased understanding of nutrient management plans and how they can improve nutrient management decisions.

    4) Improved understanding of nutrient dynamics in high tunnels compared to field production.

    5) Increased use of soil and tissue testing to aid in nutrient management. 

    6) Improved soil quality in high tunnels through the proper use of organic soil amendments. 

    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.