David R. Montgomery

At the end of January 2019, I attended the annual conference of No-Till on the Plains in Wichita. Here are my notes from the first keynote address, by David R. Montgomery and Anne Biklé:

• based on their second book of the same name; also wrote "Dirt" and "Growing a Revolution"
• Montgomery's day job: university geology professor
• Earth is the only planet we know of with soil, as opposed to regolith.
• A nonillion (30 zeroes) microbes live on the planet, enough to stretch to Alpha Centauri and back.
• Soil degradation is global, but regeneration is happening in many places.
• Historically it was the plow, not the axe, that caused degradation.
• Farming began in river valleys and spread up the hillsides.
  • soil flowed downhill and eroded away
  • boom & bust cycle is clear in Greek valleys that have survived 3 civilizations.
  • delay from bust to boom is due to soil regeneration, documented by Plato.
• Nature doesn't build soil as fast as we can erode it, but we can.
  • percent organic matter of today's soil is only about 50% that of virgin soil.
  • conventional tillage erodes about 1.54 mm/year, while geological processes build 0.3 mm/year. But no-till agriculture can build 0.8 mm/year.
  • Even if loss rate was just 1 mm/year, that's 1m in 1000 years.
  • The only continuous farming has been in river valleys where silt is deposited to replace erosion.
• Montgomery & Biklé bought a house in Seattle with an "old growth lawn" on soil bereft of organic matter.
  • brought in OM from various sources, did not dig it in; also applied worm tea.
  • Mulch decomposed as fast as they could put it in, but built an inch of topsoil in 6-7 years.
• Beneficial nematodes feed on bacteria and deposit nitrogen-rich manure right by plant roots.
• Plant exudates feed bacteria and fungi, whose metabolites feed the plants.
  • the rhizosphere (root zone) is a gut, but also a brain.
• Chemical fertilizers are seductive and dramatically build the plant above ground, but the roots and soil life are underdeveloped.
• The soil microbiome was documented earlier than the human one, but all macroscopic creatures have one.
  • There is a very strong analogy from the human to the plant microbiome.
  • Most of ours is in the colon mucus layer. Dendritic cells reach into the colon from outside to fetch molecules to activate T cells.
  • In many ways the gut is the seat of intelligence.
• Microbes got a bad rap due to the germ theory of illness.
  • Bad (disease) microbes live in relationship with many friendly ones.
  • As infectious diseases got controlled, chronic diseases took their place.
  • Hypothesis: we're missing our friendly microbes.
  • The colon is not a garbage dump, it's a garden ecosystem and medicine chest.
• Processing grains strips off the fiber, removing the food our microbiome needs.
  • B. theta (Bacterioides thetaiotaomicron) alone has genes for 300 carbohydrate-digesting enzymes, while our human genome codes for only 20.
• Short chain fatty acids produced by gut microbes, such as acetate & butyrate, boost health in many ways.
  • about 40% of your body chemistry is of bacterial origin.
  • We are what our microbiomes eat, so mulch your soil inside as well as out!
• A root is a gut (inside out), but a brain as well.
• So how do we take this garden experiment large scale?
  • general rule: "Ditch the plow, cover up, and grow diversity."
  • Specific practices need to be tailored to the specific setting. Subsistence farmers worldwide work intensively at small scale.
  • Cattle are self-propelled methane digesters; they speed up soil regeneration.
  • LaCanne & Lundgren study: regenerative agriculture is 2x more profitable than conventional, has 10x fewer pests.
  • There is no phosphorus shortage; we just need more arbuscular micorrhizal fungi to make it available.
  • Healthy soil from regenerative ag has comparable yield to chemical ag with no downsides and better food quality.
  • Organic farming simply isn't good enough; we need regenerative ag.