Soil Steamer Helps Grower Control Weeds, Pathogens
After struggling to control a soil fungus called sclerotinia that was attacking some of his most profitable crops, Curtis Millsap of Millsap Farms in Springfield, Mo., applied for a SARE grant to obtain a soil steamer to treat the problem (Sustainable Agriculture Research & Eduction;
    Curtis grows organic garden produce for his CSA, which limits methods that can be used to treat diseases and pests. After trying some high cost products to deter the black, node-like fungus that was killing 50 to 70 percent of his lettuce plantings alone, he went looking for other methods and heard about soil steamers.
    European producers have used steam treatments to kill soil pathogens and weeds for many years, but the idea is relatively new in the U.S. Curtis located a mid-1970’s soil steamer in Vermont, and was awarded a SARE grant to purchase the machine.
    The used soil steamer cost $4,000 (a brand new soil steamer can cost $20,000 or more). Curtis invested an additional $1,500 in repairs and parts, and another $1,000 into hoses and tarps.
    To use the soil steamer, the unit is parked next to the growing beds. A diesel burner boils water, then pushes steam at 15 psi into a 2-in. dia. 50-ft. hose, which is used to direct steam into a planting bed. A steam “soaker hose” further distributes the steam into the entirety of the bed. The bed must be tarped and sealed to hold in the steam.
    “You need a pretty decent seal,” Curtis says. He uses 6-mil. Plastic buried along the edges or sealed with sandbags. As the steamer heats up, the tarp will puff up and a cloud of steam is seen above the bed. Curtis treats the top 2 in. of soil to 180 degrees.
    It takes about 2 hrs. to steam-treat a 3-ft. by 100-ft bed – about the same amount of time it takes to set up the system, Curtis says. Each treament takes between 5 to 10 gal. of diesel fuel. He noted that the method gives almost complete weed and pathogen control. He is very pleased with how the soil steamer solved his immediate problem, but is not sure what the long term effects on soil health might be. To date, Millsap Farms has steam-treated 27,000 square feet of their covered growing space since aquring the soil steamer in the summer of 2019, and Curtis hopes to move to selective steaming every 2 to 3 years now that the problematic soil fungus is under control.
    Contact: FARM SHOW Followup, Millsap Farm, 6593 N Emu Lane, Springfield, Mo. 65803 (ph 417-839-0847,; Millsap Farm on Facebook and Instagram).

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2020 - Volume #44, Issue #4