PRELIMINARY FINDINGS ON PRODUCING ORGANIC VIDALIA ONIONS

George E. Boyhan*, Raymond Hicks, C. Randell Hill

University of Georgia, Department of Horticulture, East Georgia Extension Center, PO Box 8112, GSU, Statesboro, GA 30460, Email: gboyhan@uga.edu

There has been interest in producing Vidalia onions organically among both conventional and organic growers. In the 2000-2001 season we began to look at producing onions organically. Starting with conventionally produced transplants that were transplanted at standard commercial spacings on beds prepared with 4-6 inches (10.2-15.2 cm) of incorporated compost and 2,500 lbs/acre (2,802 kg/ha) rate of fresh poultry litter. This was sidedressed with an additional 2,500 less/acre (2,802 kg/ha) poultry litter. Yields were about half of conventional onion production. In 2002-2003, production of organic transplants with 4 inches (10.2 cm) of incorporated compost with 1 ton/acre (2.24 tonnes/ha) rate of poultry litter, which was followed by an additional sidedressing of 1 ton/acre (2.24 tonnes/ha) rate of poultry litter resulted in similar findings. The weight of harvested transplants was about half that of conventionally produced transplants. In the 2002-2003 and 2003-2004 seasons various natural mulches were evaluated for weed control. They included wheat straw, oat straw, Bermuda hay, pine straw, and compost. None of these performed better than hand weeding and the wheat straw, oat straw, and Bermuda hay actually reduced yields apparently due to allelopathic effects. Finally in the 2003-2004 season rates of poultry litter from 0-10 tons/acre (0-22.4 tonnes/ha) were evaluated for transplant production with rates of 6, 8, and 10 tons/acre (13.4, 17.9, and 22.4 tonnes/ha) yielding plants comparable to conventional transplants. Work continues in the area of organic Vidalia onion production. One of the greatest challenge for future work will be finding a cost effective and practical method of controlling weeds in transplant production.

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