The Carbon Farming Solution

A Global Toolkit of Perennial Crops and Regenerative Agriculture Practices for Climate Change Mitigation and Food Security


Excerpted from The Carbon Farming Solution: A Global Toolkit of Perennial Crops and Regenerative Agricultural Practices for Climate Change Mitigation and Food Security, Eric Toensmeier, Chelsea Green Publishing, 2016. Please consider joinging my mailing list.


High in the mountains of Veracruz, Mexico, a small cooperative is practicing agriculture in a way that fights climate change while simultaneously meeting human needs. Although millions of people around the world use these practices in some way, people in Western nations are largely unfamiliar with them, and there is little coordinated support to encourage farmers to adopt them. But if widely supported, implemented, and developed on a global scale in conjunction with a massive reduction in fossil fuel emissions, these "carbon farming" practices--a suite of crops and practices that sequester carbon while simultaneously meeting human needs--could play a critical role in preventing catastrophic climate change by removing carbon from the atmosphere and safely storing it in soils and perennial vegetation.

Pico de Orizaba, Veracruz, Mexico

Figure i.1. At 5,636 meters (18,491 feet), Pico de Orizaba towers over the highland cloud forest landscape in Veracruz, Mexico. The humid tropical highland cloud forest of this region is home to 10 to 12 percent of the country’s plant species on only 0.8 percent of its land.

The cloud forest region of Veracruz, Mexico, is unique and beautiful. This humid tropical highland ecosystem combines a mostly temperate canopy of trees such as oaks and hickories encrusted with epiphytic ferns, orchids, and bromeliads with an understory of mostly tropical vegetation such as cannas, wild taros, passion fruits, and tree ferns. Mexico is one of the five most biodiverse countries in the world, and this cloud forest is home to 10 to 12 percent of the country’s plant species on only 0.8 percent of its land. It is also home to 550 species of ferns and 750 plants found nowhere else in the world.

But although it has a long history of human use, the cloud forest is disappearing. Between 70 and 90 percent of it has been deforested, and what remains is highly fragmented with only tiny pockets of old growth. Much of the former forest is degraded pasture. The clouds that give the region its name don’t just bring rain. Moisture comes in the form of "horizontal precipitation"--fog from the coast that is captured by the epiphyte-covered trees. Water slowly makes its way through the spongy forest floor to streams and then to rivers. Intact cloud forest provides a year-round flow of water to drier regions downstream. In deforested areas, rain instead brings floods followed by dry riverbeds.

Many people in this region are farmers. Cattle and coffee are the primary products. Neither provides much income, and cattle farming as practiced degrades the soil. But people are creative and resilient and are actively experimenting with alternatives. One model that provides income while preserving much of the forest and its functions is the cafetal, an agroforestry system in which farmers grow coffee in the cloud forest understory. The cafetales help maintain the cloud forest’s ecological function and integrity. For example, pasture has no frog species, while cafetales have 12 compared with cloud forest’s 21. Capture of horizontal precipitation is good as well. Cafetales also sequester a lot of carbon in their forest soils and the biomass of the trees and coffee shrubs.

To Ricardo Romero of Las Cañadas, the small cooperative described above, cafetales don’t provide enough income to farmers, however. Nor do they provide farmers with anything close to a balanced diet. He is working to develop food production systems that provide a complete diet while incorporating as much of the ecosystem function of the cloud forest as possible. Such systems could also serve as corridors to reconnect fragments of intact forest. And it could do all this while sequestering impressive amounts of carbon, helping return our world to a livable climate.

In 1988 Romero began managing the site for pastured cattle. Over the ensuing seasons, he observed the continued degradation of the soils and ecosystem functions. Degraded soils give up much of their carbon to the atmosphere as carbon dioxide, a greenhouse gas. In 1995 he sold his cows and undertook an impressive ecological restoration effort, propagating and planting 50,000 native trees on 60 hectares (148 acres) while allowing another 40 hectares (99 acres) to regenerate naturally. This was the beginning of an ecotourism enterprise that included tours of an awe-inspiring old-growth cloud forest.

Romero also planted native trees on 22 hectares (54 acres) of the remaining pasture and carefully reintroduced cattle. This system, called silvopasture, combines livestock production with the ecological benefits of trees, including soil regeneration and capture of horizontal precipitation. Silvopasture sequesters carbon in the soil and the biomass of the trees. From there the team at Las Cañadas developed a successful organic dairy business.

In 2006 Ricardo and his team formed a cooperative, which today has 22 worker-members. In 2007 they hosted a workshop with permaculture co-founder David Holmgren and decided to change direction toward even greater self-sufficiency. Instead of exporting nutrients from the farm in the form of cheese while buying in organic fertilizers to replace them, they began to focus on raising as much of their own food, firewood, and building materials as possible, and generating income from training others in these techniques. Permaculture provided a design framework and principles with which to do so. Today a tour of their farm is like walking through an encyclopedia of sustainable practices and crop diversity. But Romero and his team are doing something very important beyond practicing small-scale sustainable agriculture, fostering community self-reliance, creating jobs, improving biodiversity, and bringing degraded land back to life. These same practices sequester carbon, making Las Cañadas a showcase of some of the world’s best climate mitigation techniques.

Las Cañadas in Veracruz, Mexico

Figure i.2. An aerial view of Las Cañadas in Veracruz, Mexico. The many sustainable practices employed at Las Cañadas also sequester carbon, helping to mitigate climate change while producing food, fodder, materials, chemicals, and energy. Photograph courtesy of Ricardo Romero.

In this book the term carbon farming is used to describe a suite of crops and agricultural practices that sequester carbon in the soil and in perennial vegetation like trees. If widely implemented, these practices have the capacity to sequester hundreds of billions of tons of carbon from the atmosphere in the coming decades. And if we combine carbon farming with a massive global reduction in fossil fuel emissions, it can bring us back from the brink of disaster and return our atmosphere to the "magic number" of 350 parts per million of carbon dioxide. Unlike high-tech geoengineering strategies, these practices can also feed people, build more fertile soils, and contribute to ecosystem health.

This may seem like a bold claim--and it is--but as we scramble for solutions to our climate catastrophe, the incredible sequestration potential of the crops and practices I describe in this book has been largely ignored. In chapter 3 we’ll look more specifically at the available data on sequestration rates, as well as some of the challenges of quantifying it. Despite the challenges and the need for additional research, the evidence is already clear: these crops and practices have the potential to contribute mightily to what is perhaps the most pressing issue of our time.

Maize and beans polyculture

Figure i.3. Las Cañadas practices annual cropping methods that sequester carbon. In this photo, maize and beans are intercropped in a polyculture system. Management of this field uses carbon-friendly practices including cover cropping, crop rotation, and compost application.

Carbon farming can take many forms. First and simplest are modifications to annual crop production to reverse the loss of soil carbon from tillage. For example, Las Cañadas practices biointensive crop production with very high yields in small spaces through sophisticated organic techniques. Organic practices like this have been found to sequester more carbon than even the best conventional annual cropping systems. Their larger milpas, or crop fields, demonstrate carbon-sequestering agroecological approaches to production of maize, beans, and soybeans, including crop rotation, cover crops, and contour hedgerows. Although these practices have a fairly low carbon sequestration rate, they are widely applicable and easily adopted and thus have great global mitigation potential. They also allow us to continue growing the crops we know and love.

Certain livestock systems also constitute carbon farming, which is especially significant because both extensive grazing and confined livestock production (which depends on annual crop production for feed) have been identified as part of the climate change problem. These carbon farming livestock production systems are climate-friendly even when we account for methane releases. For example, Las Cañadas practices managed grazing, fodder banks, and silvopasture--all of which have been shown to sequester carbon in addition to their other benefits. Improved livestock production models typically have a low to moderate carbon sequestration on a per-area basis, but like improved annual cropping systems, they don’t require people to change their diets. Given that more than two-thirds of global farmland is pasture, there is great potential to scale up these practices to mitigate climate change.

Dairy cows grazing in silvopasture

Figure i.4. Livestock can also be raised using techniques that sequester carbon. At Las Cañadas, dairy cows graze under native alder trees in a carbon farming silvopasture system. Photograph courtesy of Ricardo Romero.

It is perennial crops, however, that offer the highest potential of any food production system to sequester carbon, especially when they are grown in diverse multilayered systems. (On the other hand, these systems can be challenging to establish and manage and many people are also not interested in changing their diet to new and unfamiliar perennial crops.) With their plant nursery and seed company, Romero and Karla Arroyo have assembled a world-class collection of perennial crops for their climate with a special focus on perennial staple crops, analogs to maize and beans that grow on trees, vines, palms, and herbaceous perennials. The cooperative has also planted a highly diverse bosque comestible, or edible forest, of these species in a system called multistrata agroforestry--the gold standard of biodiversity and carbon sequestration in agriculture.

Ricardo Romero of Las Cañadas with perennial staple crops

Figure i.5. Perennial crops have high carbon-sequestering ability. Ricardo Romero of Las Cañadas with perennial staple crop plantings that provide protein (perennial beans), carbohydrates (banana, peach palm, air potato), and fats (macadamia).

In their quest for self-sufficiency, resilience, and livelihoods, Las Cañadas is also interested in more than food. It produces many of its own materials, chemicals, and energy. One of their emphases is a 2-hectare (5-acre) planting of clumping bamboos sufficient to provide building materials for all members of the cooperative for the next 100 years. Bamboo is a powerful climate mitigation tool as it stores lots of carbon in the soil and in its woody parts. Because few resources cover "industrial crops" such as bamboo that not only provide the material, chemicals, and energy that communities need, but also sequester significant amounts of carbon, I devote the entirety of part 4 to these incredible and typically overlooked crops.

Ricardo Romero with edible shoots of giant timber bamboos

Figure i.6. Bamboo is an outstanding building material and a powerful tool for sequestering carbon. Ricardo Romero with edible shoots of giant timber bamboos in a bamboo grove at Las Cañadas.

All that said, producing food, growing industrial materials, and sequestering carbon is not enough for a 21st-century farmer. Agriculture must also adapt to a changing climate. Las Cañadas has a stated goal to "establish production systems that are resilient to prolonged droughts, excessive rains, floods, or abnormal frosts . . ." Although carbon farming practices aren’t necessarily, by definition, adaptive, in practice almost all of them are. This is a great co-benefit of carbon farming: Not only do they, by definition, help mitigate climate change, but they also help ecosystems and communities adapt to it. Among many agricultural adaptation techniques on display at Las Cañadas are increases in soil organic matter, crop diversification, and livestock integration. Many carbon farming practices and crops also yield as well or better than conventional agriculture.

Many of the crops and practices I describe in the chapters ahead are already implemented on a scale of hundreds of millions of hectares globally, although they are still a small fraction of the nearly 5 billion hectares (12 billion acres) of world farmland. These are not minor or marginal efforts, but win--win solutions that also provide food, fodder, and feedstocks while building soils and preserving a climate amenable to civilization. At present, the tropics have stronger carbon farming options than colder climates; many of the agroforestry techniques that have the highest sequestration rates are largely confined to the tropics, at least at present, and most of the best perennial crops available today are also native to, or grown best in, the tropics. The head start the tropics have on carbon farming provides an excellent opportunity for wealthy countries to repay climate debt by bankrolling mitigation, adaptation, and development projects in the Global South and to take lessons from the endeavors already under way there.

Defining Carbon Farming

There are several, sometimes conflicting, definitions of carbon farming currently in circulation. Most definitions agree that the term refers to farming practices that sequester carbon. Some stop there. For example, here’s such a definition from the Marin Carbon Project: "Carbon farming involves implementing practices that are known to improve the rate at which CO2 is removed from the atmosphere and converted to plant material and/or soil organic matter. Carbon farming is successful when carbon gains resulting from enhanced land management and/or conservation practices exceed carbon losses."

Some other definitions explicitly link carbon farming to carbon offsets. Offsets are a strategy wherein entities that release greenhouse gas emissions pay other entities to sequester equivalent carbon or reduce equivalent emissions. These credits are typically traded on markets. There are two primary problems with carbon offsets. One is that even when they’re functioning optimally, they don’t reduce the total amount of greenhouse gases and instead just maintain their current dangerous level (unless a "shrinking cap" is built in, which has not yet happened anywhere to my knowledge). Two, and more important, is that they have largely failed to work and have also been vulnerable to corruption. For the record, I’m opposed to the use of offsets as a climate change mitigation strategy and don’t include them in the definition I use in this book.

For an expert perspective on the subject, I wrote to Dr. Rattan Lal, the director of the Carbon Management and Sequestration Center at the Ohio State University, to ask if carbon farming explicitly requires a link to offsets, and/or to financing more generally. Dr. Lal is the author of several key articles that serve as a theoretical underpinning for this book. Dr. Lal provided me with his definition of carbon farming. First, he said that farming implies products or ecosystem services. For example, hog farming produces pork, and organic farming provides the service of cleaner water downstream. He went on to define carbon farming as "a system of increasing carbon in terrestrial ecosystem[s] for adaptation and mitigation of climate change, [to] enhance ecosystem goods and services, and trade carbon credits for economic gains." In response to my question, Dr. Lal said that while paying the farmer for the service of carbon sequestration is essential to the definition, offsets were not an obligatory mechanism for doing so as long as the farmers were remunerated "in one way or the other."

Does this mean you can’t say you are carbon farming if your farm or ranch sequesters carbon, but you don’t get paid for it? It depends whose definition you like. What’s clear is that it is impossible to scale up the use of carbon-sequestering agricultural practices to the level that could provide serious mitigation without major financing efforts in place. We’ll discuss the world of carbon finance options in chapter 27.

This book doesn’t offer a prescription for a percentage of cropland that should be used in a particular way. (The many factors that go into selecting appropriate strategies for any given region or farm are touched on in part 5.) Nor is this book a how-to manual, although following up on the references to a given section will frequently provide such information. Nor does it focus on strategies for agriculture-related emissions reduction or adaptation to a changing climate. Likewise, reforestation and timber plantations--both excellent and essential climate mitigation strategies--are outside of its agricultural purview. And you will not find much information on the economics and profitability of these practices here.

What this book does offer is a toolkit for communities, governments, and farmers. It is a starting place for selecting appropriate crops and practices for your home region. It provides the rationale behind carbon farming and discusses strategies for global implementation. And it delves into improved annual cropping and pasture systems, two sets of mitigation strategies that have gotten a lot of attention lately. (You will learn that both annual crops and pastures sequester much more carbon when trees are added to them.) The core of this book unpacks the impressive and neglected climate mitigation potential of perennial crops and perennial cropping systems. This includes first-of-their-kind comprehensive profiles of perennial staple crops that provide protein, carbohydrates, and fats, and perennial industrial crops for materials, chemicals, and energy.

Ultimately the goals of this book are to place carbon farming firmly in the center of the climate solutions platform, steer mitigation funds to the millions of people around the world who are already doing the work, and help ignite a massive movement to transform global agriculture.

Carbon farming alone is not enough to avoid catastrophic climate change, even if it were practiced on every square meter of farmland. But it does belong at the center of our transformation as a civilization. Along with new economic priorities, a massive switch to clean energy, and big changes to much of the rest of the way our societies work, carbon farming offers a pathway out of destruction and a route to hope. Along the way it can help address food security, injustice, environmental degradation, and some of the core problems with the global food system. In the pages to come we’ll explore the promise and pitfalls of this timely climate change solution.