Development of Organic Nutrient Management Recommendations for High Tunnel Raspberry Production

View the project final report

Commodities

• Fruits: berries (brambles)

Practices

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

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. Solar heat is passively collected to elevate temperatures allowing for season extension both in the spring and fall. High tunnels offer an inexpensive method to increase the length of the season which increases availability of local produce and earning potential for growers.

In addition to extending the season, this production system offers protection from wind and rain damage, protection from some insects and diseases as well as birds and some varmints. This unique environment presents an opportunity to develop a cold climate organic fall bearing raspberry production system that takes advantage of the protection the tunnel offers to reduce inputs to manage pests and disease as well as increase production potential by extending the season. Although there is great potential for the use of high tunnels for small fruit production, there is little research-based information about management of fruit crops in high tunnels.  The benefits that this production system offer, increased farm income potential, reduced use of chemical inputs, increased availability of local fresh produce are consistent with the NCR-SARE sustainability goals to improve environmental quality and quality of life for farmers and rural communities. 

There is little information available to growers focused on organic nutrient management of raspberries, and even less is known about organic high tunnel raspberry production, therefore it is difficult for growers to know appropriate amount and timing of nutrient applications to the crop from different organic materials and as a result, nutrient deficiencies and/or over applications lead to poor crop health and reduced soil heath. While organic nutrient sources provide many advantages and can be an excellent source of nutrients, improper use of organic nutrients can lead to the problems such as salt accumulation, soil nutrient imbalances and improper nutrient supply to the crop. As raspberries are long-lived perennials, it is difficult to correct soil imbalances as incorporation of amendments in established plantings is not possible and it is therefore critical to manage nutrients properly. The breakdown of organic matter, and therefore the availability of nutrients to the crop are directly influenced by soil temperature and moisture, which can be very different in the high tunnel compared to the field. In addition, the crop demand for nutrients is often much greater in the high tunnel due to the increased growth. These two variables; uncertainty of nutrient release from organic matter and intense crop demand for nutrients has made managing nutrients in organic high tunnel raspberry systems challenging. 

Short-term Objectives: 1) Increased 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.Intermediate-term Objectives: 1) Improved nutrient management in high tunnels 2) Improved soil quality in high tunnels through the proper use of organic soil amendments 3) Increased use of soil and tissue testing to aid in nutrient management.