Compost Tea Brewer.
Aerated Compost Tea Brewer
Brew biology-rich liquid extract from compost or worm castings. Aerated. Used same day. Soil drench or foliar spray.
What aerated compost tea is
Aerated compost tea (ACT) is compost extracted into water under continuous aeration for 24-36 hours. The aeration multiplies aerobic microorganisms 10-1000×. The result: a microbial inoculant for soil or plant surfaces.
| Component | Purpose |
|---|---|
| Compost / vermicompost | Source biology + nutrients |
| Water (dechlorinated) | Carrier; chlorine kills microbes — let municipal water sit 24h or use rainwater |
| Microbe food (molasses or kelp) | Energy for microbe multiplication during brewing |
| Continuous aeration | Keeps brew aerobic; without air → anaerobic + bad smell + plant-toxic |
| Mesh bag | Keeps solids contained; can be removed after brewing |
ACT vs compost extract vs leachate
| Type | Process | Use |
|---|---|---|
| Aerated compost tea (ACT) | 24-36 hr aeration with food source; multiplies microbes | Microbial inoculant; soil drench or foliar |
| Compost extract (non-aerated) | 20-30 min stir/agitate; releases biology + nutrients | Quick soil inoculant; less microbial diversity |
| Compost leachate | Liquid drained from active compost pile | Variable; can be anaerobic — dilute heavily; use with caution |
| Manure tea | Manure soaked in water | Nutrient-rich; pathogen risk; require composting first |
| Plant tea (comfrey, nettle, etc.) | Plant matter soaked + fermented | Nutrient extraction; sometimes anaerobic; dilute |
Application timing
| Use | Frequency | Notes |
|---|---|---|
| Soil drench | Monthly during growth season; before transplant | Apply to moist soil; rinse residue off seedling leaves |
| Foliar spray | Every 2-4 weeks during disease pressure | Apply early morning; spray to drip; can suppress mildew, etc. |
| Seedling start | One drench before transplant | Inoculates root zone |
| After tilling / disturbance | Once | Restores microbial community |
| Compost pile inoculation | One drench at start | Speeds decomposition |
Critical: use within hours
The aerobic microbes in ACT consume oxygen rapidly once aeration stops. Within hours at room temperature:
- 0-4 hours after pump off: Tea is alive and biologically active. Apply now.
- 4-12 hours: Microbe count drops; aerobic species die back; anaerobic species increase
- 12+ hours: Tea may smell foul; potentially plant-toxic. Don't use.
Brew → apply same day. Don't store.
Warning: the science is contested
Compost tea has enthusiastic advocates and skeptical scientists. Documented benefits: microbial diversity addition; some nutrient release; some plant immune-system stimulation. Less documented: claims of disease suppression, dramatic yield increases, "drinking water for plants."
Reality: ACT is one tool of many. It works best as part of a larger soil-building program (compost + cover crops + reduced disturbance) — not as a substitute. Don't expect magic.
Free under CC BY 4.0. Cite as "OAT Compost Tea Brewer (openagriculturetechnology.com)". Methodology from Elaine Ingham (Soil Food Web) and contemporary microbial inoculant research.