As a young geologist, it took me a while to appreciate the importance of soil and the opportunity soil restoration presents for addressing key challenges humanity now faces. Over time, studying how erosion moves rock, sediment and soil to shape landscapes, I became familiar with how soil both influences and reflects the evolution of topography. We’re all familiar with the topographic displays of bare rock in the Grand Canyon, sharp-angled mountain peaks, and the smooth, rounded profiles of soil-mantled slopes in the rolling hills of California. But I also came to notice that prosperous regions tended to have rich, fertile soil. Impoverished ones did not.
The state of the soil was not just of scientific interest. It was of fundamental importance to human societies.
The oldest problem
My 2007 book, Dirt: The Erosion of Civilizations, grew out of an interest in how our treatment of the land influenced the longevity of civilizations. I found that soil erosion and degradation played a far larger role in human history than I was ever taught. Societies that degrade their land do not stand the test of time.
What lies at the root of the problem? The plow. Consider the state of a freshly plowed field. That bare soil translates into vulnerability to erosion by wind or rain. While it takes nature centuries to build an inch of fertile topsoil, an afternoon thunderstorm can strip as much off a freshly plowed field. Society after society in regions around the world gradually plowed their way into poverty, from Classical Greece to the American Dust Bowl.
Yet the problem of soil degradation is not just ancient history. It is still with us and one of the least recognized, and most serious, facets of the environmental crisis facing humanity today. In 2015, the United Nations Food and Agriculture Organization reported that under conventional practices the world loses another third of a percent of its agricultural production capacity to soil degradation each year. And while the soil on about a third of the world’s cropland is already seriously degraded, U.S. soils have lost about half their soil organic matter. These trends seriously undermine efforts to feed the world’s growing population.
Soil cores with differences in soil quality resulting from differing farming practices. Photo: D. Montgomery
Nature’s hidden half
Fortunately, soil degradation is also one of the most solvable challenges we face. I didn’t learn this from studying history. I learned it in my yard, as my wife turned our Seattle lot into a verdant garden—and changed the way we saw soil.
When we bought our house, the yard hosted a scraggly lawn with wretched soil, hard khaki-colored dirt with about 1% organic matter and nary a worm to be found. Anne set out on an organic matter crusade, layering compost and mulch on garden beds to reintroduce organic matter to the soil. In just a few years time, we found our soil turning darker brown and our plants thriving. Now, a decade later, the carbon content of our soil is up to almost 10%. We explored this transformation in The Hidden Half of Nature and came to realize the foundational role that microbial community ecology plays in soil fertility as well as plant and human health.
Growing solutions
Restoring the soil in our yard to build a garden happened far faster than nature could have made soil. And this led me to look at the question of whether we can rapidly reverse the historical trend of soil degradation—and whether solutions can scale from small subsistence farms in the developing world to large commodity crop operations in the developed world. To investigate, I visited farms around the world that had restored fertility to the soil and life to the land. In Growing A Revolution, I describe how adopting conservation agriculture practices—combining minimal ground disturbance, cover cropping, and complex crop rotations—can restore fertility to agricultural soils and help address critical issues humanity faces today: feeding the world, mitigating climate change, conserving biodiversity, and reducing pollution.
The author’s backyard garden. Photo: A. Biklé
Naturally, specific practices to adapt these general principles will vary across regions with different soils, climates, crops, economies and cultures. The lack of a simple recipe presents a tremendous challenge. But it also provides opportunities for scientists to work in conjunction with farmers to rethink conventional agriculture and evaluate the effects of regenerative practices on soil health. Basically, we need to put soil ecology back on par with soil chemistry and physics in our philosophy of farming—and invest in the science behind the transition to conservation agriculture.
I never thought I’d write an optimistic book about the environment. But the farmers I visited who had adopted regenerative practices were using far fewer chemical inputs and far less diesel, and were much more profitable than their conventional neighbors. Their stories offer hope for wider adoption of farming practices that are not only good for farmers and rural communities but also protect our environment and can help secure a sustainable agricultural foundation for humanity’s future.