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[compost_tea] CT in The Washington Post
A Cuppa Made of Compost
By Adrian Higgins
In a Virginia field, 50 organic gardeners gather around Elaine Ingham for
what is likely to be the weirdest cooking demonstration they have ever seen.
Ingham's dark, bubbling brew is not from the garden but rather for the
garden. Into a 35-gallon kettle of water she has thrown measured amounts of
dried seaweed and an inky liquid called humic acid.
"We have got loads of good stuff going into the mix," she says, filling a
nylon sock with screened compost and earthworm castings. Soon, this "tea
bag" is submerged in the water and bombarded by bubbles produced by an air
This is neither high cuisine nor dark sorcery, but the latest innovation
in the world of organic gardening and farming.
Liquid fertilizers made from manures and compost have been around for
centuries. What's new are the bubbling technique and specific ingredients,
which cause the growth of beneficial microbes that displace and even go
after all the bad spores and germs that prey on and kill plants.
Spray the tonic on the leaves, and the bad bugs have nowhere to land, say
advocates. Pour it on the soil, and you form a protective barrier for the
Enthusiasts say that when used repeatedly, the tonic revitalizes soil and
allows the cultivation of plants without the need for chemical fertilizers
Among the testimonials: roses that never get black spot; thick, green
turfgrass; ornamentals of amazing vigor and health -- all without the use of
environmentally harmful chemical fertilizers and pesticides. Organic farmers
are using the tea to repair strawberry fields rendered lifeless by toxic
fumigants. Growers of crops such as potatoes have seen greater yields using
no chemicals. Some are even spraying it from crop dusters, said Ingham, a
soil scientist and consultant to organic farmers. She heads a laboratory
named Soil Foodweb Inc., based in Corvallis, Ore. An early pioneer of the
technology, she is regarded as a leading light in organic gardening and
Not everybody is convinced.
"I have a lot of colleagues rather concerned about the hype," said Linda
Chalker-Scott, an associate professor at the Center for Urban Horticulture
at the University of Washington. "We are all waiting for the science behind
Ingham and other scientists who advocate the product say lab tests reveal
three basic beneficial aspects of compost tea: plant nutrients;
biostimulants such as enzymes and amino acids; and beneficial bacteria,
fungi and nematodes (wormlike animals) that suppress disease and may also
fight plant pests.
Chalker-Scott said Ingham is "an extremely good soil scientist," but her
data have not yet been subjected to sufficient review by other scientists.
One of the problems, said Chalker-Scott, is that every batch of compost tea
seems to produce different results, making it difficult to conduct more
definitive studies that might isolate the merits of one microbe over
Another concern is that the brewer might inadvertently create a brew
containing E. coli bacteria. Ingham says this is a valid concern but only if
correct steps are not observed. Any compost containing animal manures should
be thoroughly composted at 130 degrees for 10 days.
Even then, the gardener should make sure that the brew remains aerobic and,
in summer months, reduce the level of molasses to a teaspoon, she said.
Alternatively, use compost not made with animal manures or use the
earthworm castings, she said. They are sold in bags at garden centers.
If the scientists are squabbling, gardeners, farmers and manufacturers of
equipment and supplies are forging ahead.
"When it comes to to things in organic farming, in general the farmers
tend to be quite a few years ahead of the scientists," said Steve Diver, an
agricultural specialist with Appropriate Technology Transfer for Rural
Areas, a nonprofit funded by the U.S. Department of Agriculture that
provides technical advice to small farmers.
He said the compost teas have yielded remarkable results. When it was used
on a field of bell peppers succumbing to viral disease, usually a death
knell in the vegetable garden, it not only stopped the virus in its tracks
but also allowed infected plants to recover. "This is absolutely
mind-boggling that an organic approach was able to arrest a virus and get
the crop to grow out," he said.
Diver said if you were to look at a leaf through a microscopic hand lens
you would see hairs so thick that they resemble a jungle. By coating all
those surfaces with compost tea, the good microbes provide a barrier to any
bad ones that want to feed on the plant. "There's no room for them, there's
no food for them, and they are knocked out of the loop," he said.
Compost tea sprayed at the base of a plant feeds and invigorates a
critical part of the plant called the rhizosphere, he said.
Gardeners prepared to make a trip to the pet store can make their own
brewing kit using aquarium equipment.
Ready-made versions, some costing in excess of $1,000 and geared to
commercial customers, are also available. Some manufacturers are getting
into the homeowner market.
SoilSoup makes a 6.5-gallon brewing kit and has started selling commercial
dispensers to garden centers, where customers can arrive with their own
containers and fill up for a fee. The stations are called SoilSoup Kitchens
Another company, Keep It Simple Inc., makes a five-gallon kit for the home
Ingham, on her Web site, lists and rates brewers (www.soilfoodweb.com). Go
to Research/Resources. Under Articles, see Compost Tea.
Some machines are more efficient than others, and some don't grow
beneficial fungi, which she considers a key ingredient for disease fighting.
Mary Robson, an extension agent in Renton, Wash., said that gardeners have
made non-bubbly compost teas for thousands of years for their nutrient
values alone. In the Pacific Northwest, where the brewed article has taken
off among gardeners, "we all want it to work," said Robson. "We don't know
exactly whether, or if, it does. At least, I don't."
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