The Johnson-Su Bioreactor: What You Need to Know
- SaskSoil
- 7 days ago
- 2 min read
How does a Johnson-Su bioreactor work?
The Johnson-Su bioreactor works by composting organic materials in aerobic condition, ~70% moisture content, in an undisturbed pile for 12 months. Vertical airshafts left from removing the pipes after one day allow ambient air to move through the pile, supporting beneficial fungi and bacteria while preventing anaerobic conditions. The result is a stable, biologically active compost rich in soil microbes.
What is Johnson-Su compost used for?
Johnson-Su compost is used as a soil/seed inoculant, not a fertilizer. It is typically applied at low rates (2lb/acre or 2.2 kg/hectare) to:
Increase soil microbial diversity
Improve nutrient cycling
Strengthen plant–microbe relationships
Support soil carbon storage and increased total soil nitrogen
Is the Johnson-Su bioreactor suitable for Saskatchewan farms?
Yes. The Johnson-Su bioreactor is well suited to Saskatchewan cropping and grazing systems because it is low-input, scalable, and adaptable to prairie conditions. It can be integrated into grain, forage, and mixed farming operations focusing on long-term soil health.
What makes Johnson-Su compost different from regular compost?
Johnson-Su compost is designed to be fungal-dominant and biologically diverse, whereas conventional compost often focuses on nutrient content or rapid decomposition. The goal is to rebuild soil biology rather than supply nutrients.
Does Johnson-Su compost replace fertilizer?
No. Johnson-Su compost is not a direct fertilizer replacement. It supports soil biological function, which can improve nutrient efficiency and reduce/eliminate reliance on inputs over time, depending on the system and practices.
How much Johnson-Su compost is applied per acre?
Because it is used as a biological inoculant, application rates are typically very low, often measured in pounds per acre rather than tons.
Who developed the Johnson-Su bioreactor?
The system was developed through the research of Dr. David C. Johnson and Hui-Chun Su Johnson, whose work focuses on restoring soil microbial communities to improve farm productivity and ecosystem health.
Learn more:
Watch: Johnson-Su Bioreactor Â
Subscribe to Dr. Johnson’s You Tube Channel.