Compost tea is a watery extract of compost that can be applied to both the soil and directly to plant surfaces. Home made bio-extracts of this type have been in use for centuries due to their perceived effects on plant health and vitality. It has not been until recently however that actively aerated compost tea has emerged on the scene. The technology involves agitating compost in a water bath to dislodge bacteria and other microbes as well as humic substances. Microbial foods are then added to the liquid to promote multiplication and growth while air is bubbled into the brew to keep it from becoming anaerobic (without oxygen) while the microbes are multiplying. Actively aerated compost tea typically takes from 12 to 24 hours to “brew” – at which time the microbes have taken up all of the added food and become dormant. Actively aerated compost teas do not have a long shelf life however, and in fact, unless aeration continues they should be used within 12 hours of production.
Disease Control
Strawberries and the Severity of Botrytis cinerea
The effect of compost extracts on strawberry yields
and in the suppression of grey mould, Botrytis cinerea,
in strawberries was studied over a period of two
growing seasons on an organic, market garden farm in
the southern interior of British Columbia.
Aerobically prepared extracts improved yields (1.70 ± 0.08 t/ha)
over the control (1.36 ± 0.11 t/ha) and water spray (1.37 ± 0.09)
treatments and also reduced disease severity.
Dilute extract reduced the incidence of the disease to a
greater extent than all other treatments.
Sylvia E. Welke
Journal of Sustainable Agriculture, Vol. 25(1):
57-68 (2004).
Insect Control
“Our experiments on the effects of vermicompost teas on nematodes were in the laboratory and greenhouse, in soils that had been artificially infested with the root knot of nematode (Meloidogyne incognita), which is a very serious pest of a wide range of crops all over the world. The differences in growth between treatments, in response to the vermicompost teas were spectacular, and the reductions in numbers of root knot galls on the tomato roots in response to the vermicompost tea applications was considerable.” Also, “aerated vermicompost teas suppressed the aphid populations significantly”.. - Clive A. Edwards, Norman Q. Arancon, Eric Emerson and Ryan Pulliam - Soil Ecology Laboratory at The Ohio State University in Columbus, Ohio.
Plant Growth
The Effects of Compost Tea On Golf Course Greens Turf and Soil On
Blair, Marney (1), CONFORTI, CHRISTA (1), Hutchins, Kevin (2), Koch, Jean (1).
Pest management on golf courses has traditionally included regular fungicide applications to the greens. Many of these fungicides have the potential to harm wildlife, humans, or move into groundwater. In an attempt to reduce the need for fungicides and improve the overall health of turf and soil, the Presidio Golf Course conducted a field trial to evaluate the effects of compost tea applications on golf course greens under real-world conditions. Greens were sprayed at a rate of one gallon of compost tea per 1000 square feet for twelve months. Applications occurred weekly during times of high disease pressure, and bi-weekly during times of moderate or low disease pressure. Turf was evaluated for color, density, overall quality, thatch depth, root length, mycorrhizal root colonization, and disease, insect, and weed incidence. Soil was tested for pH, carbon dioxide level, oxygen level, turf nutrient levels, and bacterial and fungal biomass. Turf treated with compost tea had longer root length, less disease, and higher density than untreated turf. Compost tea has become an integral part of Presidio Golf Course pest management and the overall turf maintenance program. Further trials are needed to evaluate various application rates and application methods to determine the potential effects of compost tea on golf course soils. (1)The Presidio Trust, (2) Arnold Palmer Golf Management Company, USA
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