Make Biologically-Active Compost
in a Bioreactor

Healthy Soil is Living Soil

Healthy soil is teeming with life, yet most of this vibrant world is too small to be seen. This incredible ecosystem, known as the soil microbiome, is a complex web of bacteria, fungi, nematodes, algae, protozoa, tiny microarthropods, and more. Healthy soil functions as the digestive and immune system for plants, meaning it makes nutrients available for plants to use and protects them from disease. Healthy soil also performs many ecosystem services such as water regulation, supporting biodiversity, and carbon sequestration.

The soil microbiome thrives in the top 10 centimeters of the ground, but take makes it incredibly vulnerable. Extreme heat, cold, dryness, or excessive moisture can be destructive to this vital community. (Furthermore, the microbiome is severely disrupted by conventional agricultural practices like intensive tillage, soil compaction, and the use of agri-chemicals such as petroleum-based fertilizers and fungicides.)

Animals naturally carry their own microbiomes in their guts—a place that's warm, moist, and constantly supplied with food. Animal droppings, distributed by insects, naturally replenish the soil microbiome. This fundamental connection between animals, insects, and land ensures that the soil's microscopic inhabitants are continually refreshed and supported.

Nematode found in compost

The Consequences of Disconnection

When animals are disconnected from the land, this crucial life cycle weakens, leading to depleted soil microbiomes and degraded soils. This results in several critical problems:

Compromised Nutrient Cycling: Microbes are essential for breaking down organic matter and making nutrients available to plants. Without them, plants struggle to access the food they need.
Reduced Water Holding Capacity: A healthy soil microbiome builds soil structure, which helps the soil absorb and retain water, making it more resilient to drought and reducing runoff and the risk of wildfires.
Depletion of Soil Carbon: Healthy soil, with its thriving microbial life, stores carbon as organic matter. When the microbiome is degraded, the soil loses its ability to build and hold this vital carbon, significantly reducing overall soil function, including its fertility, structure, and ability to support life.
Collapse of the Food Web: This breakdown at the lowest level of the food web has cascading effects. Fewer microbes mean fewer insects and worms, which in turn means fewer birds and other animals. We're witnessing this alarming decline in biodiversity globally.

Restoring the Balance

In regenerative agriculture, carefully managed grazing animals are reintroduced to the land. This practice often leads to dramatic improvements in degraded soil and a significant increase in soil carbon because the animals' presence helps restore and maintain the vital soil microbiome.

But what if you can't bring animals back to the land? An innovative alternative is to use biologically-active compost from the Johnson-Su Bioreactor, developed by Dr. David Johnson and his wife Hui-Chun Su. This bioreactor creates an ideal environment for a diverse array of microorganisms to flourish, especially fungi. It is a no-turn (static), aerated composting system that can transform virtually any organic matter into a potent soil inoculant, offering a powerful way to reintroduce life to your soil.

Building Your Modified Johnson-Su Bioreactor

This modified design uses easily sourced materials to create an effective, no-turn composting system.

Materials You'll Need:

Wire Fencing: 5 meters of 1-meter-high wire fencing (used for keeping out wild boars). Cut the fencing into a 4 meter piece and a 1 meter piece. Do the same for the weed barrier.
Weed Barrier: 5 meters of 1-meter-high woven plastic weed barrier that allows air and water to pass through. If you don't want to use plastic, it is possible to use a bamboo sunscreen that is 1 meter wide. You might need to tie together two bamboo screens to reach 4 meters. If you use bamboo screens, you might be able to use chicken wire instead of the stronger boar fencing.
Twine

"Animal Fence" This wire fence is enough to make four bioreactors.

Construction Steps:

Outer Ring: Lay out 4 meters of wire fencing. Tie 4 meters of weed barrier to the inside of this fencing. This can be done by poking holes in the weed barrier and threading the twine through the holes. Then, connect the ends of the fencing to form a large circle.
Inner Tube: Take the remaining 1 meter of fencing and tie 1 meter of weed barrier to its outside to create a tube.
Assembly: Place this inner tube inside the larger circle, creating a donut shape. This central tube is crucial for air circulation. The distance between the outer ring and the tube will be roughly 50 centimeters. Given Dr. Johnson's finding that air penetrates up to 30 centimeters, this donut design ensures optimal aeration across the entire compost from both the inside and outside.
Placement: Your bioreactor can be placed anywhere, but it's ideal if it's near a water source and potentially under a tree for some shade.

Filling Your Bioreactor

The longest part of this process is gathering your composting materials. You'll need a lot!

Material Selection: Fallen leaves are excellent. Wood chips are also good but will take longer to break down. If you use cut grass, leave it on the lawn a day or two to dry out before using it. Old manure and agricultural waste can also be used. Like regular compost, avoid weeds with seeds. This system is forgiving; you don't need to stress about precise carbon-to-nitrogen ratios.
Moisture Prep: Wet your materials thoroughly by dunking them in a water bath, then allow excess water to drain. The goal is a moisture level similar to a wrung-out sponge – damp but not dripping. Optional: To give your bioreactor a microbial boost, add some soil from a healthy forest floor or a handful of finished compost to your water bath when moistening materials.
Filling: Fill your bioreactor, packing it lightly. Avoid overly dense compaction to maintain good airflow.
Avoid Wet Manure/Food Scraps: We don't recommend adding fresh food scraps or wet manure directly. If you plan to use them, dry them first, then re-wet them in the water bath before adding. (With food scraps, try worm composting or bokashi composting.)
Initial Heat: The compost might initially heat up, especially if you include nitrogen-rich sources like manure or fresh grass clippings. This is normal and will cool down after a few days.
Worms (Optional): Once the pile has cooled, you can add composting worms (like red wigglers) if you have them.

Our filling station. The wood chips were dunked in the water bucket, then scooped into the wheel barrow to drain excess water. Then placed in buckets used to fill the bioreactor.

Filling the bioreactor. This one is with leaves. It took about 60 buckets. But to be honest, I lost count after 30!

Maintenance and Harvest

Once filled, the Johnson-Su bioreactor is largely hands-off, primarily requiring moisture management.

Moisture Maintenance: The key is consistent moisture. In dry environments, watering for about a minute every day should suffice. The compost should always feel like a wrung-out sponge – when squeezed, only a drop or two of water should come out. Don't worry about rain over-saturating it.
Water Source: Tap water is fine, though some people prefer river water or rainwater. If you're concerned about tap water, you can fill a bucket and let it sit for a day to allow chlorine to dissipate before watering your bioreactor.
Maturation Time: The time it takes for your compost to finish depends on your materials. Shredded leaves might take a year, while small woodchips could take up to two years.
Check for Larvae: At the end of summer, check for and remove any kabuto beetle larvae. They like to lay eggs in the leaves in June and July.
Harvesting: Your compost is ready when it has shrunk to about 15 centimeters (around 6 inches) and resembles dense chocolate cake.

Using Your Johnson-Su Compost

The finished compost is a potent microbial inoculant, not a bulk soil amendment. A little goes a long way!

Prepare Extract: Gently remove any worms. Mix a small amount of the finished compost in water to create a compost extract.
Application Rates:
- Farm Scale: Approximately 1 kilogram of compost extract can cover 1 hectare (or 1 lb per acre).
- Garden Scale: A handful of compost mixed into a large bucket of water is sufficient for a garden.
Application Methods:
- Seed Coating: Coat your seeds in the compost extract before planting.
- Root Dip: Dunk the roots of seedlings in the extract when transplanting.
- Foliar Spray: Apply the compost extract as a foliar spray directly onto plants.
- You can also spray your field at the end of summer or beginning of spring.

Notes:

The outer, drier part of the compost will act as a protective "skin," insulating the inner core from extreme heat and cold.
The inner tube can be pulled out after a few days. But I just leave it in there. After about a year, the hole might collapse, but you don't have to worry about it, especially if you have earthworms in the compost.
Don't let the bioreactor freeze.
While this design is scalable, try not to go smaller than a 3-meter circumference for optimal results.
This is a modified Johnson-Su bioreactor. The original design used five PVC pipes and is placed on a wooden pallet.

Case Studies

Drawdown Farm, Pakistan: In Pakistan's challenging climate, Drawdown Farm utilizes Johnson-Su bioreactors to transform degraded soils. The highly fungal-dominant compost significantly improves soil structure, water retention, and nutrient availability, enabling healthier crops with less water. This showcases the bioreactor's potential to create resilient food systems and sequester carbon even in harsh environments.

The Rodale Institute, USA: A leader in organic agriculture research, The Rodale Institute's trials confirm the Johnson-Su Bioreactor's effectiveness. Applying its compost extract dramatically increases microbial diversity and biomass, leading to improved plant vigor, nutrient uptake, and increased yields across various crops. Rodale's research provides strong scientific validation for its role in ecological restoration and sustainable food production.

New Earth Project, New Mexico: The New Earth Project, by the Upper Gila Watershed Alliance, demonstrates the Johnson-Su Bioreactor's community impact in arid New Mexico. By converting cafeteria food waste and forest thinning biomass into fungal-dominant compost, they not only address waste but also inoculate degraded agricultural land. This initiative highlights the bioreactor's role in carbon sequestration, soil health, and fostering food system resilience through education and youth engagement.

Stangl Enviro Lawn Care, Canada: Stangl Enviro Lawn Care showcases a powerful transition to regenerative practices using the Johnson-Su Bioreactor. After years of conventional methods, Mr. Stangl embraced the bioreactor to produce "Nature's Brew," an extract rich in beneficial microorganisms. This biologically-active inoculant is applied to lawns, fostering a healthy soil microbiome, improving plant health and significantly reducing the need for synthetic fertilizers and pesticides, proving that true lawn health comes from vibrant living soil.

Make Biologically-Active Compost in a Bioreactor