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Johnson-Su Bioreactor Composting

This very special type of static composting/vermicomposting method was invented only a few years ago. Once set up, the pile is never turned, though it is regularly watered and after the pile cools down you add worms. 

Trials have shown big yield increases in plant yields and carbon sequestration, even without fertilizer.  It takes a full year to mature and produces a material that looks like clay, suspends in water, and has the ability to rapidly help rejuvenate the full underground biological ecosystem. Very little product is needed by comparison to other compost (2 lb/acre), if it is added to the seed at planting. 

The material input list is much more forgiving than normal compost. Many different materials can be used, and the green to brown ratio is not very important. Dried and mulched leaves are probably easiest for a first attempt, but everything from hay to cow manure has worked (with wood chips for structure and air flow). 

The pile is constructed all at once, then left undisturbed. Air tubes deliver oxygen to the pile, with distances from air never exceeding 12 inches. The material is pre-wetted to the ideal amount by dipping materials in water and draining them. There is drainage on the bottom, which is raised, often on an old pallet. The pile isn’t allowed to dry out. An automatic sprinkler running 1-2 min every day or two can keep it simple. 

Once constructed, the pile heats up for a few days, then cools. Worms can be added (sometimes they find it with no help). It is kept moist for a full year to develop and the final material is best used by adding at planting right where plant roots will form.

There are currently two Johnson-Su bioreactors on display at Billie Park. 


The Benefits of Johnson-Su Bioreactor Compost - Dr. David Johnson  9 min long

Recent 1hr  scientific talk by Dr David Johnson (see field trials at 21 min):