Amending Colorado’s thirsty soil with compost tea

Microbial brew can stimulate the earth


For people who understand compost but are unfamiliar with compost tea, the reaction to the microbial-rich liquid brewed from compost is oftentimes repulsion — that is, until they realize it is to be applied to plants and trees, and not ingested by humans.

Compost tea, however, is exactly what it sounds like, and the process for creating it is not so different from how we brew our chamomile or green teas. It’s a brew that’s produced by submerging compost in a permeable bag in water. But, unlike the tea that we drink, compost tea is brewed at room temperature for 24 hours in a tank where pumps and motors constantly inject air — a process known as extraction.

The result is a liquid brimming with beneficial microbes, like fungi, healthy bacteria and microrisa.

“The microbes in compost tea stimulate a plant’s immune system kind of like how probiotics stimulate ours,” says Dan Matsch, manager of Eco-Cycle’s CHaRM facility and compost department. “Applying compost tea adds microbes to the soil, and having an adequate population of them helps to stabilize and stimulate soil, and it actually creates more soil faster.”

Amending soil through compost or compost tea is particularly important in Colorado, where most soils suffer from extremely low levels of microbial activity. The general rule of the green thumb is the more microbes, the healthier the soil and the plants it supports.

“Most people’s soil is lacking in a percentage of organic matter, like beneficial microbials, beneficial bacteria and nutrients,” says John DiFilippi, owner of ecoLogical Lawn and Tree Care. “Furthermore, the prolonged use of synthetic fertilizers and toxic pesticides actually depletes all those good things as well as kills off earthworms and beneficial insects like ladybugs and honeybees.”

DiFilippi says that while the best thing for lawns or gardens is to apply high-quality compost directly to the soil, applying compost tea can also be very beneficial to plants. Compost tea, when applied three to six times a year, can boost the microbes in the soil, which will make plants happier and healthier.

Boulder residents interested in applying compost tea to their lawns, trees or gardens have a couple of options, depending on the level of involvement desired in the process. One option is to outsource the entire process and leave it to experts like DiFilippi.

Another option is to buy and apply. Compost tea can be purchased directly from ecoLogical Lawn and Tree Care, Eco-Cycle or in some garden centers around town. Eco-Cycle sells the tea on Saturdays at the Farmers’ Market, but if you’re looking for a large quantity, Eco-Cycle’s compost manager, Mastch, suggests coming out to CHaRM on Wednesdays throughout the season to pick it up.

Or, if you’re a true brewer, have access to clean compost and are intrigued by the process, you can make your own. Kits can be purchased that include everything needed to brew compost tea in a five-gallon bucket. However, since the tea needs to be constantly aerated, this can get a little tricky. For this reason, Mikl Brawner, co-owner of Harlequin’s Gardens, which brews and applies compost tea to its plants, says that most people prefer to buy their tea rather than brew it themselves. Whether you choose to brew or buy and apply, it’s important that the compost tea be applied to plants and soil immediately — ideally within six to eight hours — for it to be most effective.

“Compost tea is a little complex,” says Brawner. “We’re still trying to understand it, and that’s tough because you can’t see what you’re doing. These are microscopic beings. An expert told me that the only way to really know its value is to put it on the plants and see how they respond.”