Unproven benefits of compost tea

September 12, 2016

Compost tea, which has long been touted as a garden miracle worker, has yet to prove its worth to scientists.

Rob Chase, a Nevada County Master Gardener, says there is plenty of anecdotal evidence of the benefits of compost tea, but as yet no research has proved those claims. Compost tea — a brew of water and compost that is used as a soil drench or foliar spray — still is worth experimenting with, Chase says.

Here are some brewing tips:

— When brewing compost tea use only quality, pathogen-free compost or worm compost. If you brew the tea from compost that has pathogens, you will then spread those to your plants.

— Use only pure water for the tea. City water can contain chlorine or chloramine, which means the water must sit for several days so that the chemicals will dissipate.

— The correct way to brew compost tea requires using an aerator, such as an aquarium bubbler or other air pump. The air helps microbes thrive and expand, boosting the benefits of the compost tea, in theory.

— You can spend several thousand dollars on a compost tea brewing system, Chase said, or you can use a 5-gallon bucket, a bag or strainer to hold the compost, and an aerator.

— For best results, use the compost tea on your plants within four to six hours after the brewing process, which can take 24 to 48 hours, is complete.

Researchers are trying to quantify the benefits of compost tea as an inoculant and a fertilizer. Although some testing has showed promise, the results haven’t been consistent. Chase says people should do their own experiments and tests.



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