Soil Carbon Sequestration: a Surprising Opportunity to Heal Ourselves and the Planet at the Same Time
Two years ago I had the good fortune to stumble into Jeff Wallin and Bob Cirino at an info session for the Bard MBA in Sustainability, a relatively new MBA program dedicated to developing business skills through the lens of sustainability. Although interested in the program, I was mainly attending the event because the global sustainability expert Hunter Lovins would be there, and I wanted to meet her. It just so happened that Jeff and Bob were also there to meet with Hunter, but because she served on the board of The Biochar Company, a startup Jeff had co-founded and Bob had left college early to join.
As I would learn that evening, biochar* held promise as one tool in a whole suite of agricultural climate change mitigation solutions for its ability to both sequester carbon as charcoal and to also serve as a valuable, multi-functional soil amendment. The Biochar Company was one of the first companies to begin the production and sale of biochar as a product, and eventually became one of eleven finalists in Richard Branson’s Virgin Earth Challenge, which offers a $25 million prize for technology proven to remove greenhouse gasses from the atmosphere.
*Biochar interlude: biochar is a term soil scientists coined to describe charcoal either in soil or made to add to soil. Scientists and practitioners around the world have discovered that biochar has a variety of unique properties in soil, such as the ability to hold water, nutrients, and the creation of habitat for soil micro-organisms. All of this in addition to the fact that the very creation of biochar is an act of carbon sequestration, because biochar itself is the resulting carbon from plant matter that would otherwise decompose and off-gas carbon into the atmosphere in the form of CO2 . You can learn more at the International Biochar Initiative’s website).
I left that night with Jeff’s business card and, within a couple of weeks, had set up an opportunity to join them on a project that summer. While the project itself provided a great learning opportunity, the more important outcome for me was to be swept into a global movement that focuses on soil health as a multifaceted solution to various social and ecological problems. What I had gotten a taste of that first night proved to captivate me as I spent more time with them: Jeff and Bob were absolutely obsessed with using biochar and other methods to build healthy soils, and had already dedicated much of their lives to this work. In fact, Bob had a Youtube channel under the name “Biochar Bob”, and had made numerous educational videos demonstrating the use of biochar around the world (I highly recommend watching these, which were largely my introduction to this topic).
I relate to you my own discovery of biochar and soil health as backstory to what I’ve encountered on this journey: the carbon sequestration potential of healthy soil as one of our greatest opportunities to reverse global warming, while solving other problems related to human health and ecological degradation. What I learned in my time with Jeff and Bob is that while biochar is an exciting solution for multiple issues, it is but one part of an array of agricultural systems that can be used to grow food in ways that feed humans, restore ecosystems, and mitigate against climate change. But before I share what some of those methods are, let me share some tidbits on soil:
- Within the planetary carbon cycle, soil is the second largest carbon sink on the Earth after the oceans. As a part of this cyclical process, plants take atmospheric carbon dioxide and convert it into biomass (their bodies) through photosynthesis and send the remainder down into the soil, where it feeds micro-organisms.
- Soil provides habitat to an extremely complex and diverse microbial ecosystem. To cite one example, Dr. James Tiedje at Michigan State University’s Center for Microbial Ecology estimates that a 1/4 acre woodlot would have about one million species of bacteria, a teaspoon of that soil housing between 600 million to 1,000 million individual bacteria. Fungus is also a key component in soil. Vast mycorrhizal networks of fungi connect individual plants together and play a critical role in the storage and distribution of nutrients and water. These networks are integral with the carbon cycle and the health of above-ground plant life (see interview with Elaine Ingham here).
- While scientific consensus is emerging on the potential amount of carbon that can be sequestered in soil, various reports as listed in this recent article from the Guardian offer news to be optimistic: a study by Rattan Lal estimates that soil carbon sequestration could offset 5 to 15% of annual fossil-fuel emissions; the National Academy of Science offers a more conservative 3% of annual emissions; and a report from the Rodale Institute in Pennsylvania claims more than 100% of global CO2 emissions could be sequestered through what they refer to as regenerative organic agriculture.
- And finally, in addition to this carbon sequestration potential, improving soil health has the following additional benefits: the ability to hold more water to hedge against drought, increase biodiversity and plant pest and disease resistance, grow healthier food through boosting nutrient density in plants, and increase productivity, or crop yields. Simply put: increasing carbon content in soils lifts many boats at the same time and is the right thing to pursue regardless of its impact on the climate.
So how do we grow food, educate, and live in ways that build healthy soil and tap into its incredible potential for carbon sequestration? Key methods include no-till farming (because tillage disrupts soil life and releases soil carbon into the atmosphere), cover cropping, improved grazing systems like Allan Savory’s holistic planned grazing method, agroforestry practices like those of Agenda Gotsch in Brazil, and the transition to growing perennials, which can help build soil and also have a higher carbon sequestration potential than annuals. Eric Toensmeier’s recent publication The Carbon Farming Solution: A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security, provides a comprehensive guide to the expansive variety of these agricultural practices, with detailed review of the scientific data available for carbon sequestration potential. The book also builds on Toensmeier’s decades of experience in the field of permaculture design and provides a comprehensive listing of perennial plant species and their associated uses.
So what’s the catch? While I am still getting a sense of the whole picture, I believe the challenge before us in realizing the soil carbon sequestration solution is that it requires the transformation of not just our agricultural system, but also the global political-economy and our cultural relationship with food and the way it’s grown. Within the environmental movement there is growing awareness of agriculture’s devastating impact on the planet. But rarely is the distinction made between industrial agriculture — the form of agriculture responsible for this impact — and ecological agriculture, the methods described above, which also include established methods like agroecology, permaculture, and countless other land management techniques. For decades, folks in these fields have been growing annuals, perennials, and raising livestock in ways that facilitate the health of their ecosystem and the humans it sustains. These methods represent a comprehensive, established, and viable alternative to conventional agriculture, and they need greater awareness and political and financial support to scale in time to address the climate crisis and provide us with the food security that their industrial counterpart does not offer.
What’s more, it is not enough to talk about soil health alone, because its well-being goes hand in hand with the systems of agriculture that get deployed on a particular piece of land. This is why we must discuss soil carbon sequestration and include in the conversation the different types of agricultural methods touched on above — which also have significant implications for carbon sequestration potential. Perennials, for example, represent a big opportunity for a variety of reasons. Additional carbon is not only stored in the plant itself, which can be a significant amount if you’re talking about tree crops with longer lifespans, but perennials also prevent the need to disrupt soil ecosystems through the tilling that is typically (but not necessarily) deployed for annual systems. Raising awareness for the soil building potential of perennial agriculture is a great way to help transition our food system towards ecologically beneficial production methods.
Perhaps most importantly, we must also question the underlying cultural beliefs that caused us to ignore our relationship to soil in the first place. At the heart of this in western culture is our false perception of ourselves as separate from and even superior to nature, when in reality we are deeply connected to and dependent upon the living systems that sustain us. Humans are nature, and as nature we must reawaken to our ecological responsibility as members of ecosystems. Soil is a habitat for billions of other beings that make life on earth possible for us, and its health also represents a profound opportunity for cultivating a thriving partnership between humans and the rest of the earth community. It is time to bring agricultural, political, and economic systems into alignment with the reality of the soil as a habitat. In doing so, we have the power to mitigate against global warming and heal ourselves and the land in the process.
With gratitude to Dale Hendricks, Rodger Savory, and others from the Soil4Climate Facebook community for helping polish this piece with me.
If you’d like to hear more about this topic, check out my Upstream Podcast interview with Jesse McDougal of Studio Hill, a farm in Vermont using animal grazing to restore degraded landscapes and fight climate change.
