Master Gardeners Build Compost Bioreactor

Master Gardeners Build Compost Bioreactor
By Norine Cepernich, Gaye Torjusen, Leslie Muennemann and Kathy Stamm, UC SM/SF Master Gardeners
 
In June, four UC Master Gardeners from the San Mateo/San Francisco Program took a class at California State University Chico, hosted by the Center for Regenerative Agriculture. Dr. David Johnson introduced us to his Johnson-Su Bioreactor system, a static aerobic compost pile that sits unturned for 12 months. The finished product is a fungal-dominant clay like compost applied as an extract, mixed as a slurry to coat seeds, or used directly as a soil amendment.
 
The compost greatly improves plant health, growth rates and crop production. Master Gardeners and friends helped fill the  Johnson-Su Compost Bioreactor on Saturday, July 20 at the San Mateo Garden Education Center. 
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There is growing research about what good healthy soil can do for our planet!
  • Good healthy soil improves human health by improving nutrient value in food.
  • Good healthy soil sequesters carbon.
  • Good healthy soil purifies water and acts like a sponge. 
  • Good healthy soil improves habitat for people and animals.
We were so inspired by the potential benefits of this composting system, that we decided to make a Johnson-Su Bioreactor at our Gardening Education Center in San Mateo.
 
By early July we had solicited three pick up truck loads of leaves, had trimmed and chipped a hedge, built our 4’ wide by 5’ high cage, and covered it with landscape cloth. We were ready to fill the bioreactor.
Master Gardeners and friends helped fill the  Johnson-Su Compost Bioreactor on Saturday, July 20 at the San Mateo Garden Education Center.
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In black cement mixing trays, we hydrated or inoculated the fill materials in a compost extract bath that was mixed over and over again until a total of three yards of dried hedge chips, goat bedding, and oak leaves, were soaked and drained. Five gallon buckets were used to fill up the bioreactor. Six four-inch PVC perforated drain pipes were placed into the contents one foot apart for air circulation. A drip irrigation system was added to the top of the pile and runs daily for one minute.
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After the filled cage rested for 24 hours the pipes were removed allowing maximum airflow into the pile. At twenty four hours the bioreactor had reached 110°F. Forty eight hours later, the bioreactor registered 134°F for the next three days before cooling. When the pile cools to 80 degrees, red worms will be introduced.
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No turning is required as the air ways created by the PVC drain pipes, inserted strategically into the mix, will provide enough air to maintain aerobic conditions.
 
Now we wait 12 months while a highly fungal compost is created and ready to use!
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In the two weeks following the assembly of the full size Johnson-Su Bioreactor many have asked if this large Bioreactor can be scaled down to a smaller size and still produce the same highly fungal compost only in smaller quantify. Since there were left over materials we decided to create a Mini Bioreactor, using a Smith and Hawkins Biostack as the frame. We added a base with holes to hold five PVC pipes, and this one is not turned and is being hydrated daily like the large Bioreactor. Otherwise, the scale of the original cage system is the same only limited to three feet tall. It will be interesting to see if we can scale down the Bioreactor system and still achieve the same results. We should know in 12 months!
 
 
Additional Information:
 
 
 
Why Build a Johnson-Su Bioreactor?

There is growing research about what good healthy soil can do for our planet!

SM/SF Master Gardeners have jumped on the bandwagon by building our own Johnson-Su Bioreactor system for improving soil, plant health, growth rates and crop production.

The Johnson-Su Bioreactor System was developed by Dr. David Johnson. It is a static aerobic compost pile, that sits unturned for 12 months. The finished product is a fungal-dominant clay like compost applied as an extract, or mixed as a slurry to coat seeds, or used directly as a soil amendment. The compost greatly improves plant health, growth rates and crop production.  

Good healthy soil improves human health by improving nutrient value in food.

In a 2003 study, Dr. David Thomas compared food composition data from 1940 with that in 1991 and found that the level of every nutrient in almost every kind of food had fallen between 10 and 100%.  “An individual today would need to consume twice as much meat, three times as much fruit and four to five times as many vegetables to obtain the same amount of mineral and trace elements as available in those same foods in 1940.” [Dr. Christine Jones]

Good healthy soil sequesters carbon.

Through the miracle of photosynthesis, plants bring atmospheric carbon down into their roots feeding soil micro-organisms. It is these microbes that make mineral and trace elements in sand, silt and clay available to their hosts and turn carbon in to stable compounds (humus).  “If all agricultural, garden and public lands were a net carbon sink, we could easily draw down sufficient CO2 to counter emissions from the burning of fossil fuels.” [Dr. Christine Jones 2008]

Good healthy soil purifies water and acts like a sponge. 

“Every one percent increase in soil organic matter (mostly carbon) represents an additional 20,000 gallons of water per acre held in the ground.” Water In Plain Sight: Hope for a Thirsty World  Judith D Schwartz 2016

Good healthy soil improves habitat for people and animals.

“The health of plants and animals depends on having a rich biodiversity throughout an ecosystem…Restoring native habitat can be done at any scale, whether it's in the forest, field, stream, or even balcony, as long as moisture, a diversity of plants and microbial life, pollinators and beneficial insects are kept in mind.”  [Community Soil, Santa Rosa, CA]