The Johnson-Su Bioreactor Enriches Beneficial Soil Fungi

Stop Turning Your Compost

Composting offers a terrific way to culture native microbes that benefit your soil. However, there is more to a good compost than simply building a pile of manure or and yard waste. Proper aeration is important to prevent overheating and to ensure that aerobic microbes dominate the mixture. This is why many large scale composting facilities turn their compost at regular intervals. In fact, many composters sold for home gardeners are also designed for frequent turning. Unfortunately, while turning does increase the abundance of aerobic microbes (and that is good), it also shatters delicate fungal hyphae before they can become fully established in the compost (and that is bad).
The reason you don’t want fungal hyphae to break is because a fungus must reach a mature size in order to maximize its ability to mobilize nutrients and reproduce.  The the bigger the fungal hyphae networks in your compost grow, the more nutrients they are able to extract and transfer from your waste material to the soil you wish to condition, and to the plants you hope to support.  A healthy fungal population will also decompose weed seeds in your compost, and reduce potential for pests and disease organisms that might otherwise dominate your compost.

A Johnson Su Bioreactor Provides Aeration and Moisture Without Turning

Dr. David Johnson of New Mexico State University has tackled the problem of producing fungal rich compost by designing a bioreactor that provides proper aeration and moisture without turning.   His design works well for small farms and household gardens.  It can also be upscaled for large commercial operations by simply maintaining the principles of including enough finely chopped woody material (straw, dry leaves, sawdust, etc) to feed fungi (fungi love a high fiber diet) and by providing adequate air and moisture without turning.  Watch the video below, contributed by David Johnson, to learn how this is done.  Dr. Johnson’s research is helping growers worldwide increase yields while building soil health and mitigating climate change, so you might also want to check out other videos on his YouTube Channel.

By the way, many of my blog posts include affiliate links, but for the record, I have no sort of financial affiliation with David Johnson.  I simply share his perspective that we can use microbes to increase agricultural productivity, build food security, improve human nutrition, and combat climate change.

Putting the Bioreactor to the Test

We have evaluated David Johnson’s bioreactor on our own site in Southern New Mexico, and in Longmont, Colorado.   The setup takes a bit of work, and requires quite a bit of starting material, so it is important to plan ahead.  While having adequate material on site is rarely an issue for farmers, home gardeners often build their compost using a few table scraps at a time, and the bioreactor needs to be filled all at once.

My advice to growers who don’t have enough material on hand is to wait until fall, gather at least a pickup bed full of dry leaves from your neighbors, chop them with a mulcher, and get started.  As for your table scraps-you will provide more nutrients to your garden if you chop them up and place them directly in the soil then you will by composting them.  Just don’t put perishable food waste near plants that are close to harvest.  I’ll expand on mulching food scraps in another post.  

The video below, taken from bioreactor compost prepared at Schultz Family Farms in Longmont, Colorado, emphasizes one of many very long, dark septate fungi we found in the bioreactor only two weeks after we initiated the process.  A diversity of fungal spore types, bacteria, and protists are also visible in the video.  This is what you want good compost to look like under the microscope.



When Does a Bioreactor Make Sense to Use?

Now, a few very green minded growers I’ve spoken to have challenged the wisdom of using a leaf mulcher and going through all this effort to chop woody material and build compost, when microbes will eventually break it leaves down anyway.  I agree that microbes will do the job in time.  If all farms were currently using permaculture approaches on quality land today,  and if all sites were free of environmental threats that inhibit plant growth, I would agree that this approach may not be necessary.  My goal is to provide tools that work in the real world and meet the grower where he or she is at.  A composting bioreactor makes sense to maintain on any site that may be prone to pests, disease, heat waves, or unexpected cold spells that challenge plant growth.  Why?  Because bioactive compost is a necessary ingredient for making compost teas rich in minerals, fungi and bacteria.  These compost teas can increase plant resistance and resilience to stress.

Seeds mixed with fungal rich compost are more likely to germinate and establish with minimal effort.  Compost teas can rapidly disperse microbes and nutrients on leaf surfaces to protect them from a wide range of environmental threats, including pest and disease outbreaks, heat waves, and cold fronts.


Learn more about soil microbes by joining our Microbial Analysis for Growers course.

Learn more about soil microbes by joining our Microbial Analysis for Growers course.

Leave a Reply