I completed Dr. Elaine Ingham’s Soil Food Web program. I was there for the knowledge, not the credential. From there I went deeper into soil microbiology, forest ecology, and the specific role of mycelium in soil health. I raised my own beneficial nematodes. I’ve also picked up a mild spore allergy along the way, which tells you something about how much time I’ve spent in the grow room. This recipe comes from all of that — plus years of hands-on testing on our property in the Texas Hill Country.
I made compost tea in 30-gallon batches in a cleaned pickle barrel. Our farm crops were consistently head and shoulders above what neighbors were growing. The flavor and nutrition were in a different league. That’s not something you can fake with a bag of fertilizer.
Aeration Is Not Optional
I want to be direct about this before anything else: compost tea needs to be aerated. Non-aerated brews create anaerobic conditions that favor harmful bacteria — the kind that cause food poisoning. People do make unaerated teas and they can work, but there is real risk involved. If you go that route, the tea has to be used immediately after brewing. Do not let it sit. I’ll cover the unaerated approach at the end of this article as a weather-dependent workaround, but the recipe below is fully aerated and that’s what I recommend.
Equipment
The equipment scales to whatever batch size you need. I brewed 30-gallon batches in a cleaned old pickle barrel. For smaller gardens a 5-gallon bucket works fine — the principles are identical.
What matters most is air volume. You need enough oxygen moving through the brew to keep the entire batch aerobic. I ran a 1,750 GPH pump on my 30-gallon barrel — that’s more airflow than most people use and I think that’s exactly right. Starving the brew for oxygen defeats the purpose. I also used a specialized PVC aerator designed for tea brewing rather than a standard airstone. The distribution pattern matters for larger batches.
Inoculant Sources
The inoculant is where this recipe differs from most of what you’ll find online. I used three sources together:
- Soil from an old-growth tree stand on our property — undisturbed forest floor soil carries the richest fungal networks and the most diverse microbial community you can find locally. Sample every six inches from a three-foot hole to pull organisms from multiple soil horizons.
- Finished mushroom compost — spent substrate from mushroom cultivation is loaded with fungal biomass and partially broken-down organic matter that feeds the broader community.
- Worm castings — dense in plant growth-promoting bacteria and already biologically active. Castings kick-start the bacterial population faster than soil alone.
Using all three gives you a broader community than any single source. You’re not just growing bacteria — you’re trying to replicate the full soil food web in a barrel.
Why Molasses and How the Succession Works
Bacteria need food to establish, and molasses is that food. This is not just a recipe ingredient — it reflects how the soil food web actually builds. Bacteria colonize first because they have the food source. Once bacterial populations reach density, the protozoa and nematodes follow — because they eat the bacteria. The fungi thread through the whole system. What you’re doing in a 48-hour brew is running a compressed version of the succession that happens naturally in healthy soil over months.
Not all molasses performs equally. I tested several brands and Plantation Blackstrap unsulphured molasses produced the most active cultures consistently. Blackstrap has higher mineral content than lighter varieties, which supports a broader community. Unsulphured is non-negotiable — sulphur is antimicrobial and will suppress the organisms you are trying to grow.
Compost Tea Recipe
What You Need
- A clean barrel or bucket — size to your needs
- High-volume air pump — don’t undersize this
- Tea brewing aerator
- Non-chlorinated water — chlorine kills the microbes you are trying to culture. Filtered, distilled, or water left to off-gas overnight.
- Unsulphured blackstrap molasses
- Inoculant: undisturbed forest or pasture soil, finished mushroom compost, worm castings — use all three if you can
- Compost tea brew bag — keeps the larger material contained and filters it out when you’re ready to apply. Don’t fill it more than half full; the contents need to move freely with the aeration.
How to Make Compost Tea — Step by Step
- Fill your barrel or bucket with non-chlorinated water. Soil temperature should be 60°F or above — microbial activity below that threshold is too slow for a good brew.
- Add molasses at roughly a 1-2% solution. For a 30-gallon batch that’s approximately 2.5-5 oz per gallon scaled down, or about 75-150 oz total. Start toward the lower end — overfeeding can crash the brew.
- Add your inoculant. For a 30-gallon batch I used several generous scoops of each — forest soil, mushroom compost, and worm castings. There’s no single right ratio. You’re seeding a community, not following a chemical formula.
- Set up your pump and aerator. Get the water moving well before you walk away. You should see active turbulence across the whole batch.
- Run for a minimum of 48 hours. Check at 48 hours — if you have a microscope, look for protozoa and nematode activity alongside the bacterial population. If the community looks thin, run another 12 hours and check again. Do not exceed 72 hours.
- Apply immediately after brewing. Compost tea degrades fast once you stop the aeration. Use it the same day.
What to Look for Without a Microscope
Before I had a microscope I brewed 24-36 hours and hoped for the best. If you’re in the same position, here’s what to watch for: active foam on the surface is a good sign — that’s biological activity. The smell should be earthy and pleasant, like good soil after rain. If it smells rotten or sulfurous, something has gone wrong. A rich brown color and active bubbling at the 36-hour mark generally means you have a live brew worth applying.
How to Apply Compost Tea
Dilute one part brewed tea to twenty parts water for foliar spray or general soil drench. For bare root trees and non-native plantings, apply to the root zone at planting and again two to four weeks later. I’ve also applied undiluted at four gallons per half row for field crops — which is what the sweet potato experiment below reflects.
Apply in the early morning or evening. UV light kills the organisms you just spent 48 hours growing.
One important note on sprayer setup: remove the built-in filter from your sprayer and use a large nozzle. Nematodes are large enough to get caught by standard sprayer filters and fine nozzles — you’ll strain out exactly what you’re trying to apply.
The Cold and Hot Weather Workaround
When temperatures are too cold or too hot for safe brewing — and there is a real temperature window for this — you can make a quick compost extract or unaerated tea as a stopgap. Steep your inoculants in non-chlorinated water, add molasses, and use it immediately. Do not let it sit. Do not brew it overnight and apply it in the morning. The anaerobic bacteria that develop in an unaerated brew can carry pathogens that cause food poisoning, and that risk climbs fast with time. This is a field expedient, not a method.
Sweet Potato Results
The photo below is from my own test on a 100-foot row of sweet potatoes on our Hill Country property. I applied brewed tea without dilution at four gallons to one half of the row. The other half received no treatment. No other fertilizers or soil amendments were applied to either side.
The treated side produced noticeably larger leaves. This is consistent with what soil food web science predicts — a more active microbial community improves nutrient cycling and availability, which shows up in leaf size and plant vigor before it shows up in yield. I’ve replicated similar results with trees and garden beds over the years.
How Compost Tea Fits into the Soil Food Web
Dr. Elaine Ingham’s soil food web research established that healthy soil is not primarily a chemical system — it is a biological one. Nutrients become available to plants not through synthetic inputs but through the activity of bacteria, fungi, protozoa, nematodes, and larger organisms processing organic matter and cycling nutrients into forms plants can use.
Compost tea works by reintroducing and amplifying that biological activity where it has been depleted. Tilling, chemical inputs, and compaction all damage the soil food web. Inoculating with locally sourced, actively growing microbial communities is one of the most direct ways to begin restoring it.
Mycelium plays a specific and critical role in this system. Fungal networks extend the effective root zone of plants, move water and nutrients across distances roots cannot reach, and form symbiotic relationships with plants that most conventional agriculture has essentially eliminated. The inoculant mix above — particularly the old-growth forest soil and finished mushroom compost — brings those fungal organisms into the brew alongside the bacterial community. It is not a purely bacterial tea, and that distinction matters.
If this area of science interests you, Elaine Ingham’s Soil Food Web Institute offers formal training I found genuinely valuable. The understanding it gave me changed how I approach every aspect of growing, from mushroom cultivation to tree establishment to garden management.
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A note on Dr. Elaine Ingham: Dr. Ingham passed away on February 16, 2026. Her contribution to our understanding of soil biology was enormous, and her work changed the way a generation of growers thinks about the ground beneath their feet. The Soil Food Web School she founded continues her work. If you want to go deeper into the science behind everything on this page, it’s the right place to start: soilfoodweb.com.