In this episode of In Search of Soil, we're talking to microbiologist and co-creator of the Johnson-Su bioreactor, Dr. David Johnson about composting, fungal-dominated compost, and just how much compost you really need to help improve the soil and rebuild the microbial communities there. Dr. David Johnson is an adjunct professor for the College of Agriculture at Chico State University and a Faculty Affiliate for the Center for Regenerative Agriculture. He has done numerous research on soil, fungal-dominated compost, and carbon sequestration. He and his wife, Hui Chun Su Johnson, have co-created the Johnson-Su bioreactor. More on David's work: https://www.csuchico.edu/regenerativeagriculture/bioreactor/david-johnson.shtml

Build a Bioreactor: https://youtu.be/q8o_f8jL3g8

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In this episode of In Search of Soil

• Introduction to today's guest, Dr. David Johnson (00:30)
• One thing about microbes that really stood out to Dr. Johnson (01:32)
• Agriculture's current understanding of the importance of microbes (02:55)
• The biggest misses in preserving soil biology (04:30)
  • What used to be grasslands have now become deserts due to overgrazing (06:25)
  • Restoring the soil is restoring an entire system (08:03)
• The change in the soil that allows it to grow more (08:43)
  • Carbon needs to return to the system to rebuild the soil (10:35)
  • Fungi are what have been destroyed the most (11:18)
  • Bring back the photosynthetic capacity of the soil (12:00)
• What happens above ground that helps below ground (13:33)
• Changing management practices: from poor soil to Great Plains soil (15:18)
  • Experiment: replacing nitrogen with biology (18:20)

• The relationship between plants and the soil microbiome (19:48)
• Compost application: sparse application vs. dumping a lot into the soil (21:10)
• Putting high-quality compost, that is both an inoculant and food source, into poor soil (24:45)
  • Farming becomes fun when you bring back the system and its functionality (27:15)
• Having root interaction immediately available upon germination (28:03)
• Coating seeds with the community it needs (29:35)
• The basic principles around Johnson-Su bioreactor compost (30:42)
  • Aerobic
  • 70% moisture content
  • Undisturbed
  • Worms (vermicompost)
• The big differences between Johnson-Su bioreactor compos and traditional compost (33:22)
• What are you missing when you try to speed up the composting process? (35:50)
• X days to finished compost: only looking at half the picture (37:47)
• Johnson's opinion on forcing air into the composting system (39:30)
• Application of theories in different climates (42:00)
• Scaling the composting system up and down (45:15)
• Composting what biodegrades easier and using woodchips in the garden (48:22)
  • Mulching in the garden to combat weed issues
• Going about making seed coatings: make some slurry (51:05)
• Using compost extract as tea to get microbes on the soil surface (53:00)
• Correlation of weed pressure and microbial population (55:40)
  • Fertilizers make the soil more amenable to weed growth (56:55)
• Is vegetable rotation enough to be considered "permanent ground cover"? (58:55)
• Getting to a point where a system grows itself with no need for compost (01:00:30)
• Opinion on soil remineralization (01:02:10)
  • If the element is there, it can be extracted by microbes
  • If the element is not there, you might have to supplement
• Pairing a nitrogen-fixer with a non-nitrogen-fixer or rely on biology (01:05:35)
• Does the above ground biomass correlate to product quality? (01:07:25)
• What happens in the soil that negatively affects the plant above ground (01:09:45)
• Healthy soil grows healthy plants resistant to weed and disease (01:12:15)
• Thoughts on adding mycorrhizal fungi into the system (01:15:10)
• Ways to tell your soil's health (01:17:02)
• Is it worth it for a farmer to purchase a microscope (01:19:45)
• Organic matter percentage and upper limits (01:20:20)
• You don't need the extracts if you have grazing (01:23:23)
• Closing remarks (01:24:55)
  • If you just observe, you'll figure out what you need to do next