In terms of civilization, it is more valuable than gold. The soil is the foundation for food and stability required for organized, structured society. Without good, productive soils, everything else starts to erode away. The loss of productive soil is a sad tale that shows up over and over throughout the history of mankind.
This repeated trend throughout the earth’s millennia of agriculture intrigued David Montgomery, a geologist at the University of Washington in Seattle, who spoke at the Conservation Tillage and Technology Conference in March.
“As a geologist I started looking at soils and studied erosion around the world. A decade ago I got really interested in how soil erosion affected ancient civilizations. That culminated in a book that looked at the role of soil degradation in the decline of ancient civilizations. There is a depressing component to that because you see the same story play out in society after society. Societies that degraded their land didn’t prosper in the long run. You can look at places like Syria or Libya as modern examples of places that degraded their land to the extent that it compromised their descendants greatly in terms of their prosperity and stability,” Montgomery said. “Then my wife and I bought a house in north Seattle that came with a yard with dirt — not much in the way of soil. It had an old growth Seattle lawn with six inches of tangled roots. We pulled that lawn off to make a garden and we didn’t find a single worm. It was dead dirt. We embarked on an attempt to bring life back to the soil to make a garden.”
In the small-scale urban backyard project, Montgomery and his wife had surprising success in rebuilding their soil with the addition or organic matter, increasing biological diversity and minimizing soil disturbance.
“We restored the soil really fast, much faster than I would have guessed from the research I had done on ancient civilizations. Nature takes a long time to make an inch of soil, but we can do it much faster by taking advantage of our ability to bring organic matter in to enhance what nature would take a long time to do. We wrote a book about that experience and the parallels between what microbial activity does in the soil to help plants and what happens in the human gut. They are kind of like the same system. Then I was left wondering if we could do that same thing on a global scale on farms around the world,” Montgomery said. “I took some time off of teaching at the University of Washington in Seattle to visit farmers around the world who had already restored fertility to their land. I brought a shovel with me and said, ‘What’d you do? What did you start with and what do you have now? Can we dig a hole here and at your neighbor’s place?’ I was really impressed how rapidly some farmers had been able to restore fertility to their land and how much they had been able to reduce their use of fertilizers and pesticides. No-till was a sort of foundation for re-building soil health.”
The crucial role of reducing and eliminating tillage initially surprised Montgomery.
“What do you think of in terms of icons for agriculture? The plow. It is on the seal of the USDA — Thomas Jefferson’s plow is still there. Societies throughout history have relied on it. The idea that plowing could degrade soil over the long run is a little counter intuitive but it is pretty solid in terms of causing soil erosion. If you till the soil you are leaving it vulnerable to the wind and the rain until the next plant comes up. If you do that for generations it can really add up,” Montgomery said. “I found three simple principles that were in common among the farmers who had reversed the trend of ancient soil degradation and rebuilt the fertility of the land. The principles are: ditch the plow, cover up with cover crops, and grow a diversity of crops, whether in the cash crops or cover crops. Some of the farmers I visited with were growing corn, soybeans and wheat and adding diversity with cover crops in between. They had all greatly reduced fertilizers and pesticides while maintaining yields, which increases farmer profits. I view rebuilding soil health as the best long-term investment a farmer can make but it can also pencil out over the short run too. We are starting to learn about the role of soil life bacteria and fungi in plants and crops. They can help rebuild soil health at a pace that, as a geologist I find quite fast.”
Montgomery’s first popular book, “Dirt,” was a fairly grim look at how erosion undermined ancient civilizations around the world. The follow up “Growing a Revolution: Bringing Our Soil Back to Life,” is more of a good-news environmental story. Montgomery’s most recent book, “The Hidden Half of Nature,” co-written with his wife, Anne Biklé, looks at the power of microbes in the soil and in human health. His books are available at books.wwnorton.com/books/Growing-a-Revolution/.