How to Brew Aerated Compost Tea
Aerated compost tea (ACT) is brewed by aerating a mixture of finished compost and water for 24--36 hours, allowing the microbial population in the compost to multiply dramatically. The resulting liquid is applied as a soil drench or foliar spray with the goal of introducing beneficial.
Aerated compost tea (ACT) is brewed by aerating a mixture of finished compost and water for 24—36 hours, allowing the microbial population in the compost to multiply dramatically. The resulting liquid is applied as a soil drench or foliar spray with the goal of introducing beneficial microorganisms to the soil or plant surface.
The claims surrounding compost tea range from credible to overblown. The credible ones — that ACT delivers concentrated beneficial microorganisms and soluble nutrients to the soil — have reasonable support. The overblown ones — that it cures plant diseases, eliminates the need for fertilizer, or dramatically outperforms regular compost application — do not hold up in controlled trials. Per Cornell Cooperative Extension, the honest assessment is that ACT is a useful supplemental tool, not a replacement for the foundational practice of incorporating solid compost into soil.
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How Aerated Compost Tea Differs from Compost Extract
These two terms are often confused.
Compost extract (non-aerated): Compost steeped in water for 24—48 hours without aeration. Per Penn State Extension, this leaches soluble nutrients and some microorganisms into solution but does not significantly increase microbial populations because the organisms are not receiving enough oxygen to reproduce rapidly.
Aerated compost tea (ACT): Water oxygenated continuously with an aquarium pump while compost brews in it. The high dissolved oxygen content supports aerobic microbial reproduction. Per NC State Extension, microbial populations in properly brewed ACT can be 10—100 times higher than in non-aerated extract.
Which to use: ACT is preferred for introducing microbial inoculum. Compost extract is adequate for delivering soluble nutrients. Most serious growers use ACT.
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