The Fifth Agricultural Revolution: Restoring the world’s soil from a geologist’s outlook
By Tom Parker
David Montgomery candidly admits that some of the statistics, studies, summaries and slides he uses during presentations were extreme examples of agricultural soil degradation and loss, and the pivotal role it played in the demise of civilizations both ancient and, unless corrective measures are taken, our own. “That’s why I use them,” he said with a wry laugh. Montgomery spoke at the Kansas Rural Center’s Annual Food and Farm Conference, held November 16 & 17 in Wichita, and attended by over 200 people interested in the local and regional food economy, and natural resources and the farming practices that protect them.
The picture he painted was bleak, but when he asked his audience whether they would prefer to live on Earth or Mars—the former shown as a blue-and-green globe, the latter a lifeless planet of red rocks and shifting sands—it seemed an exaggeration meant to provoke levity or shock.
It in no way trivialized the seriousness of his charges. Since the dawn of agriculture, soil degradation was implicit in the collapse of Mesopotamia, Neolithic Europe, Classical Greece, the Roman Empire, Easter Island, Syria, Libya and parts of China and the United States, and the pace has quickened. One-third of the world’s arable cropland has been taken out of production since the 1940s, another third is on track to be lost in the very near future, while at the same time the world’s population is expected to grow by a third.
The juxtaposition of the two planets suddenly seemed more prophetic than frivolous.
Montgomery, a University of Washington professor and author of “Dirt: The Erosion of Civilization” and “Growing a Revolution: Bringing Our Soil Back to Life,” was one of several keynote speakers at the conference. Other speakers included Anne Biklé, co-author with Montgomery of “The Hidden Half of Nature: The Microbial Roots of Life and Health,” and Mary Hendrickson, Rural Sociology Associate Professor, University of Missouri who spoke on creating community wealth through local food systems.
Montgomery’s presentation, “Growing a Revolution,” explained how as a geologist studying erosional processes that shape landscapes, he came to appreciate not only soil but the role that farming plays in both the destruction of the world’s soil and how it could help reverse the process. For the first half of his career, soil was the stuff covering up all the things he was supposed to be looking at. About ten years ago, he began questioning its effects on ancient civilizations while writing “Dirt.” He scoured the library for studies and dissertations, searched soil-degraded wastelands in Italy, Greece and other places looking for evidence of intensive farming in the distant past, and consumed every piece of literature he could find on the subject. Erosion did indeed play a role in the demise of civilizations, he concluded, but the real villain was not deforestation, as all the textbooks implied, but the plow.
“It wasn’t the axe, it was agriculture that followed deforestation,” Montgomery said. “Why was that? If you cut down trees, they grow back. You have to actively endeavor to keep them off the land. And that’s when you start to lose topsoil over the course of generations. It’s not what I thought I was writing about when I started writing the book.”
The association between healthy plants building fertile soil and healthy soil building fertile plants goes back to the colonization of the continent by land plants, when rich soil began developing. Tillage, he said, undoes that in a single path. “It’s a very effective means of weed control, but it also leaves the ground surface vulnerable to erosion by wind and rain, and that sets the stage for progressive ongoing topsoil loss that can really impact societies over time.”
There was no real data at the time for measuring the sediment flux coming off Roman fields or the water quality in Greek rivers, but by triangulating with archaeological studies and with a lot of extrapolation, he came up with quantifiable numbers that have been verified by more recent data. For conventional tillage-based erosion rates from small fields in the developing world to large-scale mechanized operations in the developed world, the median rate was about a millimeter and a half per year. “At that pace, it takes just 20 years to lose an inch of soil,” he said. “That’s fast.”
In the Palouse region near Idaho, he documented areas that lost five feet of topsoil between 1911 and 1961, or about an inch a year. Portions of the Piedmont country from Virginia to Alabama lost four to 12 inches of topsoil over the course of 200 years. The latter was catastrophic because according to journals of plantation owners and farmers there was only about six to 12 inches of topsoil to start with.
“If we can erode a third to all of the topsoil across a region once considered the original breadbasket of the early colonies, and we could do it in just a couple of hundred years, think what the Greeks could have done with their 1,200-year run in southern Greece, or the Romans in their 800-year run in central Italy,” he said. “Think what happened to Syria and Libya, places where there are Roman tax records of bountiful wheat harvests that today can barely grow anything. It wasn’t the changing climate that did them in, it was the loss of the soil.”
Soil, Montgomery said, is the interface between the geological world and the biological world, the merger of the fossil world of dead plants and creatures and the world of living things, of microbes and bacteria and worms and nematodes and other organic matter. Without that organic matter, soil is as dead as the sands of Mars.
Global statistics aside, the topic really got personal when he and his wife, Anne Biklé, bought a house in Seattle.
Biklé, a biologist, saw the lawn as a place to build the garden of her dreams. When they ripped the lawn up, however, they found not rich loamy soil but hardpan glacial till. “We lovingly call it nature’s concrete,” Montgomery said. “There wasn’t a single worm in it.”
Over the next decade, they added coffee grounds, compost, kitchen scraps, grass clippings, manure from the zoo—anything they could find. They fed the dirt until it started to become soil. The pace of the transformation shocked Montgomery. It also turned him into an incipient optimist in thinking that the fertility of the world’s farmland could not only be rebuilt, but rebuilt remarkably fast.
“Adding organic matter brought back the missing item in soil—life,” he said. “Herein lies both the good news and the bad news: the good news is that we know how to farm in ways that can restrict the loss of soil to a pace that’s close to soil being built. The bad news is that we tend to call those practices alternative agriculture.”
According to a recent study, America’s agricultural soil has lost about 50 percent of its organic matter. “It’s not because the soil is no longer there,” he said, “but because the soil no longer as fertile as it used to be. It’s been greatly masked by our technology, and the inputs we use. Agriculture is going to have to change this century. This problem is one we can actually fix, and fix remarkably fast and do it in ways that make farmers money.”
This isn’t a theoretical concept or a wild fantasy, he said, but verifiable, fact-based experience from farmers around the world practicing regenerative agricultural principles. From Canada to Costa Rica to Ghana and equatorial South Africa, he toured their farms, dug holes in their fields, and saw transformation on an unprecedented scale. By adopting conservation agricultural practices, farmers in any region of the world were matching conventional yields using far less oil and chemical inputs.
Specific practices used by farmers implementing those practices vary wildly, not only region to region but from farm to farm, he said, and need to be adapted to specific settings. “In the standardization of agronomic practices that have happened over the past hundred years, we’ve over-simplified our understanding of the soil and under-appreciated the ingenuity and creativity of our farmers,” he said. “We need to undo both of those things.”
From his perspective, the world has gone through four agricultural revolutions. The first, the idea of planting things, changed the course of human society. The second was soil husbandry, of planting legumes and rotating crops—two of the three principles of conservative agricultural practices. The third revolution was industrialization and mechanization in the 19th century, and the fourth was the ongoing biotechnology revolution. Now, he believes, we’re on the eve of a fifth revolution based on the prioritization of soil health.
No matter the location, the basic principles are deceptively simple, he said: don’t disturb the ground. “That’s a recipe for more profitable farms,” Montgomery said. “Even a geologist can tell you that.”
Montgomery’s presentation will be posted on the KRC website. The Kansas Rural Center (KRC) is a private, non-profit organization promoting sustainable agriculture and a sustainable food system.
Tom Parker is a freelance writer from Blue Rapids, Ks. and he prepared this article for the Kansas Rural Center.