Actively Aerated Compost Tea
By Claudia Mosby
Soil SecretApril 2015
By Claudia Mosby
Photos: Eric Leslie
Worm poop. Who knew of its importance in helping save the soil and, in turn, the planet? Well, Ken Waranius, for one.
Actively aerated compost tea is not your mama’s recipe. A liquid compost teeming with soil-friendly microbes—bacteria, fungi, protozoa and nematodes—this environmentally benign brew is easy to make at home for use on a variety of plants.
“In the good old days, Grandma and Grandpa used to make manure tea,” says Waranius, a gardener for more than 40 years and owner of Redding Compost Tea. “The problem with that was they made anaerobic, or non-oxygenated tea. The anaerobic microbes (like yeast) create alcohol, formaldehyde and other destructive compounds, whereas the aerobic microbes do not.”
Pumping air into the tea solution produces bubbles and thus an environment where aerobic microbes prosper, Waranius explains, adding, “While the tea has some mineral value, its main benefit is the microbes and using natural fertilizers, like worm castings, helps us maintain sustainability.”
Castings are simply a fancy name for excrement that contains these beneficial microbes used to make the compost tea. This waste can be either manure-based or cellulose-based, depending on the worm’s diet.
For the worms he raises, Waranius travels 100 miles round trip for manure from a Tehama County cattle ranch (“for its purity”) and to local restaurants for salad prep material (“nothing that’s been on a plate”) that he then puts through a continuously turning compost tunnel.
Cellulose-based castings have the added benefit of reducing the opportunity for pathogens like E.coli and salmonella.
As with the castings, so to each worm its own purpose. “Some worms move up and down (e.g., night crawlers) and their function in life is to bring easily soluble minerals like calcium and magnesium back to the soil’s surface,” says Waranius. “Some worms move back and forth (e.g., red wigglers) and their function is for composting: they eat anything that falls on the top soil.”
Waranius uses a large trommel to separate the worm from its casting and estimates he has hundreds of thousands of them. “They multiply like rabbits, doubling every two to three months,” he says. “Cocoons, the size of a BB, hatch when moisture, food availability and temperature (about 58-78 degrees) are just right.
A former self-identified “chemical guy,” Waranius changed his methods 10 years ago after walking onto a friend’s vineyard in Santa Rosa and seeing “a corner of it that was absolutely outstanding. I was amazed and asked him about it,” he says. “He told me the person tending it was using compost tea.”