High Tunnels in South-Central Alaska

High Tunnels in South-Central Alaska

High Tunnels in South-Central Alaska

Chilly Root Summer 2013 (5)

USDA invests in season extension through its Natural Resources Conservation Service’s (NRCS) High Tunnel System. Available through the Environmental Quality Incentives Program (EQIP), this practice aims to help growers extend the growing season, improve plant quality and soil quality, reduce nutrient and pesticide transportation, improve air quality through reduced transportation inputs, and reduce energy use by providing consumers with a local source of fresh produce. Since 2010, NRCS has funded the construction of over 200 high tunnels in the Homer District of Alaska.  According to Rachel Lord, grower and owner of Alaska Stems, this concentration of funded tunnels in Alaska’s Homer District was the highest in the U.S. as of 2012.

The extended season is critically important in this sub-artic region as a method to increase food security and local sustainable agricultural opportunities. However, while the general idea is that high tunnels can add two to four weeks to a growing season, Lord considered that this may not be the case in the District. She found that little research had been done in coastal Alaska to determine if this assumption, largely developed in the Lower 48 states, was the case in her region. She stated more data would be needed to understand the relationship between inside and outside temperatures and the effects of humidity when utilizing high tunnels on an Alaskan farm. Lord developed the Farmer Rancher program-funded project Monitoring Impacts of High Tunnels on Growing Conditions and Season Extension in South-central Alaska to provide the agricultural community local data to better guide farming efforts and make the most use of limited resources.

Significantly, based on the data, Lord did not see support for the idea that high tunnels alone in this area could add two to four weeks of growing season as assumed. However, the project did find that high tunnels alone provide a great amount of season ‘enhancement’ and elicited recommendations on how best use the practice.

Lord and her team, using temperature and humidity data loggers, collected data in 10 high tunnels to understand the effects of high tunnels on growing conditions at different elevations and with single- or double-poly glazing in coastal South-central Alaska. They also developed a website specifically for high tunnel owners around the state of Alaska to share and disseminate information. Lord states, “The high tunnel website developed for this project is a fantastic new resource for growers around Alaska. It compiles and documents local information gathered by the Kenai Soil and Water Conservation District, Sustainable Homer, and local growers and makes it available statewide. It allows a platform for links, resources, and updates on high tunnel growing in Alaska. In a web-based culture, having this permanent resource online is a great benefit to the growing community.”

The team provided seasonal updates on the data collection efforts at three community high tunnel meetings in Homer, with an average attendance of 40-50 growers. The data was helpful in quantifying actual gain of growing degree days, air temperature, and soil temperature inside different types of high tunnels from 10 case studies in the area. At the completion of the project, Lord concluded, “Based on our data, we do not see support for the idea that high tunnels alone in this area add two to four weeks of growing season. Season extension activities should likely be concentrated in the fall; and, regardless, some additional heat source or other temperature control methods likely must be employed to protect crops from cold temperatures. Moisture control in the fall is also a challenge that must be addressed.”

However, the results do point to the potential of extending the season with unheated high tunnels due to the increase in growing degree days by an average of 2,000 over field conditions. This increase provides a large advantage in the region.

More information on Alaska High Tunnel’s Website.

Want more information? See the related SARE grant(s) FW12-046, Monitoring Impacts of High Tunnels on Growing Conditions and Season Extension in South-central Alaska .

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