Organic Blueberry production in High Tunnels

Consumer demand for organically-produced horticultural crops continues to grow each year. The USDA has responded to this demand by increasingly providing funding for organic and sustainable agriculture. Many universities, including NC State and UC Davis, offer upper level courses in these areas and provide a space for hands on learning. UGA will now be joining these universities with the founding of the UGA organic agriculture certification program. Two acres of UGA's Horticulture Research Farm in Watkinsville have been designated as the organic teaching area. Funding for this project comes from the USDA.

Additionally, a second USDA grant provides funding for a research project titled "Out-of-season small fruit production for improved profitability of organic farming." This grant is comprised of two major research components. The first is the growing of organic southern highbush blueberries in high tunnels at the Experimental farm in Watkinsville. The second component is extension based and provides funding for large-scale implementation of high tunnels for organic highbush blueberry production in Georgia's coastal plain. This project is conducted in cooperation with Dr. Gerard Krewer at UGA's Tifton campus.

Organic blueberries receive a high price on the market but their price does fluctuate widely throughout the year due to variations in supply. Growers who can gain an edge on the market by having their berries ripen a month early or more will have a tremendous advantage in the price they can receive for their product. Therefore, technologies that induce early flowering in blueberries are currently being explored for their feasibility.

High tunnels for fruit and vegetable production continue to grow in popularity here in the U.S. and abroad. A high tunnel is similar to a greenhouse but differs on a few key points. High tunnels lack any elaborate heating, cooling, or ventilation system. Ventilation, instead is provided by rolling up the sidewalls creating a 1.5 m (5 ft.) high opening down the sides of the tunnel. Greenhouses are typically covered with a double layer of plastic while high tunnels have only one. High tunnels vary greatly in size.

For the Athens based component of this project, 6 tunnels each 5 m (16 feet) wide by 11 m (36 feet) long have been constructed. In contrast, the research taking place in South Georgia employs a much larger, multiple-bay high tunnel. High tunnels are simple enough to be used by the home gardener and the commercial grower. Potential benefits of high tunnels include season extension, reduced losses in soil fertility due to erosion and leaching, reduced need for fungicides and insecticides, and the closed environment make biological control more feasible and effective.

Inside of the tunnels are two raised beds approximately six feet wide. The beds are coverd with an eight inch deep layer of finely crushed pine bark. Pine bark, with its low acidity and porous nature provides an excellent growth medium for blueberries and other Ericaceous plants. The beds contain two rows of plants spaced at 90 cm (3 feet) between plants and 75 cm (2 ½ ft.) between plants. This spacing is considered high density for blueberries. Many growers are switching to high density planting because blueberry plants grow rather slowly and once they become overcrowded can easily be transplanted. For high tunnel planting where space is at a premium, high density planting is a must. The cultivars are Emerald and Jewel, two low chill-requiring cultivars developed by the University of Florida. Two cultivars were planted due to the lack of self-compatibility shown by many blueberry cultivars. Fertilization is provided with a granular organic fertilizer applied several times throughout the year. Irrigation is provided with micro-jet style sprinklers. Two identical control plots lacking the high tunnel were also planted for comparative purposes.

Data being recorded inside and outside of the tunnels includes microclimatic variables such as air temperature, soil temperature, and relative humidity. Data on the flowering of the plants both inside and out is also being recorded. An economic analysis will be conducted to determine the feasibility of this system for growers.

	For the Athens based component of this project, 6 tunnels each 5 m (16 feet) wide by 11 m (36 feet) long have been constructed. In contrast, the research taking place in South Georgia employs a much larger, multiple-bay high tunnel. High tunnels are simple enough to be used by the home gardener and the commercial grower. Potential benefits of high tunnels include season extension, reduced losses in soil fertility due to erosion and leaching, reduced need for fungicides and insecticides, and the closed environment make biological control more feasible and effective.
Inside of the tunnels are two raised beds approximately six feet wide. The beds are coverd with an eight inch deep layer of finely crushed pine bark. Pine bark, with its low acidity and porous nature provides an excellent growth medium for blueberries and other Ericaceous plants. The beds contain two rows of plants spaced at 90 cm (3 feet) between plants and 75 cm (2 ½ ft.) between plants. This spacing is considered high density for blueberries. Many growers are switching to high density planting because blueberry plants grow rather slowly and once they become overcrowded can easily be transplanted. For high tunnel planting where space is at a premium, high density planting is a must. The cultivars are Emerald and Jewel, two low chill-requiring cultivars developed by the University of Florida. Two cultivars were planted due to the lack of self-compatibility shown by many blueberry cultivars. Fertilization is provided with a granular organic fertilizer applied several times throughout the year. Irrigation is provided with micro-jet style sprinklers. Two identical control plots lacking the high tunnel were also planted for comparative purposes.
	Data being recorded inside and outside of the tunnels includes microclimatic variables such as air temperature, soil temperature, and relative humidity. Data on the flowering of the plants both inside and out is also being recorded. An economic analysis will be conducted to determine the feasibility of this system for growers.