Modern agriculture is all about tradeoffs. Monocrops are more “efficient,” but we lose the benefits of biodiversity. Irrigation allows drought-ridden California to keep growing strawberries and salad greens, but groundwater reserves have fallen to record lows.
What if we could develop a kind of farming with no tradeoffs? An agricultural system that produces healthy soils, high yields and a net-negative effect on greenhouse gases? A growing chorus of experts says that agricultural Shangri-La does exist, and it’s called carbon farming.
To understand how this could be so, you first need to understand a little more about farming. Driving a tractor fueled by gasoline, tilling the soil, grazing animals—most of the things we think of as farming—all of these activities release carbon, which is trapped in the soil as carbon dioxide, into the atmosphere. Indeed, farming practices account for as much as one-third of greenhouse gases in the atmosphere. The build-up of carbon dioxide and other greenhouse gases is a major driver of climate change.
Carbon farming, sometimes called resilient agriculture, encompasses a series of agricultural practices that both retain carbon in the soil and even remove carbon dioxide from the atmosphere. There is no precise formula; which techniques farmers use, and when, will depend on their location, the crops and the weather. And that makes carbon farming a lot more complicated than industrial agriculture’s “just-add-fertilizer” approach. But the idea is to use a combination of techniques, such as no-till farming, planting cover crops, management-intensive grazing and composting, to encourage plants to do their natural work.
For those unschooled in biology (or, like me, who last studied it in high school), here’s a recap of photosynthesis 101: A plant captures carbon dioxide from the air, splits off the oxygen molecules, then turns the carbon into sugars to feed itself. What’s left over, often as much as 40 percent, is exuded through the plant’s roots into the soil, where microbes feed on them and turn it into humus—rich, healthy soil that is full of stable carbon. This healthier soil helps to produce higher yields and resist droughts and floods. And by keeping carbon locked in the ground—some carbon pools can hold carbon for thousands of years—it also can help to mitigate the effects of climate change.
A 2004 study in the journal Science revealed that sequestering carbon in the soil has the potential to offset fossil fuel emissions between 5 percent and 15 percent a year. This month, the Union of Concerned Scientists reported that by making changes in its agriculture and forestry sectors alone, the United States could sequester or reduce between 2 billion and 3 billion tons of carbon dioxide equivalent by 2020. (For links to more research, visit Ohio State University’s Carbon Management and Sequestration Center.)
Carbon sequestration has great promise. But it cannot halt or reverse climate change alone. Livestock emissions—the methane released from cattle raised for beef, in particular—is arguably a more important challenge. But the focus on carbon sequestration marks a subtle shift in the debate about climate change—and it is an important one, as environmental journalist Judith Schwartz explains. Until now, discussion has mostly focused on curbing fossil-fuel emissions—the equivalent, one scientist told Schwartz, of reshuffling the deck chairs on the Titanic. Others agree: “Even if we shut down all of our carbon emissions today, we’d still need to capture what is in the atmosphere,” said Timothy LaSalle, an international consultant on sustainable agriculture and the former president of the Rodale Institute. “Nothing is proven to do that except for one thing: photosynthesis. We have to take what we have released over millennia from the soil and put it back in.”
The idea of carbon sequestration, and the agroecological methods that support it, are garnering global attention. In part, it is a response to climate change. But it is also driven by fears that the world needs more food to feed a growing population. In September, the U.N. Food and Agriculture Organization held its first symposium on agroecology for food and nutrition security. In France, where agriculture is responsible for roughly 20 percent of the country’s carbon dioxide emissions, Agriculture Minister Stéphane Le Foll called on farmers to embrace agroecological methods such as carbon farming. Agroecology “is not an angelic vision or a marginal one,” Le Foll said. “It is simply the conviction that we do not always use what nature offers us to help it thrive.”
How can we encourage carbon farming here in the United States? LaSalle, Michael Pollan and others want the federal government to pay farmers to sequester carbon. It’s a smart idea: Instead of offering subsidies to grow certain crops—and just as often not to grow them—we pay them to invest in the soil and, by doing so, fight climate change. But it won’t be an easy sell in Washington. LaSalle told me that we lack technology that is cheap and fast enough to measure how much carbon is stored. (He has suggested setting up an XPrize to develop sensors to do this.)
Moreover, adds Ricardo Salvador, a senior scientist and director of the Union of Concerned Scientists’ Food & Environment Program, ramping up carbon sequestration requires more than just applying compost or planting cover crops. To reach its potential, we would have to fundamentally transform American agriculture, moving away from annual crops toward perennial polycultures, a shift that could take decades. Salvador is one of many experts who believe that shifting cattle to pasture-based systems, with a focus on management-intensive grazing, is a more urgent task if we are to mitigate the impacts of climate change.
Still, carbon farming is an exciting idea. As Pollan eloquently argued in his keynote at last month’s New York Times Food for Tomorrow conference at Stone Barns Center, carbon farming “not only helps to mitigate climate change, but also to rebuild something just as endangered and just as important to our long-term prospects: hope. For this kind of engagement with nature completely overturns our habitual, tragic, zero-sum view of the human relationship with the natural world.” In other words, we may have at last found a win-win for agriculture.
Originally published on December 16, 2014