Regenerative agriculture does sequester carbon if the practices create a positive soil carbon budget, and by positive soil carbon budget, I mean the input of carbon into the soil must be more than the carbon losses from the soil,” said Rattan Lal, a professor of soil science at Ohio State University and recipient of the 2020 World Food Prize for his pioneering research on soil health.
Regenerative agriculture—sometimes called conservation or natural agriculture—can include a range of practices, but usually refers to things like cover cropping (planting winter soil with grasses), leaving crop residues on fields, using less or no chemical fertilizer and pesticide and not plowing up soil. When farmers employ these practices, they can help build healthier, more carbon-rich soil that more effectively draws carbon dioxide from the atmosphere and stashes away carbon.
The vast agricultural landscape of the American Midwest has significant potential. By Lal’s estimate, each acre could sequester up to 1,000 pounds of carbon a year, under optimal farming practices.
Taking the country’s two largest crops—corn and soy—which are grown on about 163 million acres, that translates to a potential of about 74 million metric tons of carbon a year.
Overall carbon emissions in the United States totaled about 1.5 gigatons in 2018. (Note that this is carbon; not carbon dioxide, which was about 5.4 gigatons.) So, according to Lal’s estimate, corn and soy acreage alone has the potential to offset 5 percent of U.S. emissions from fossil fuels.
That could potentially offset nearly half of emissions from all of U.S. agriculture.
Globally, Lal has estimated that soils could capture 180 gigatons of carbon between now and 2100, and up to 43 gigatons of that could be captured on cropland.
A body of studies puts the annual sequestration potential on global crop and pasture lands at about 1.4 gigatons of carbon (or 5 gigatons of carbon dioxide).
By comparison, carbon emissions from the fossil fuel industry, in 2019, were about 10 gigatons (or 37 gigatons of carbon dioxide).
These figures represent the “technical potential” of soils, an amount of sequestration that’s theoretically feasible, not factoring in the significant economic, political and social hurdles.
Given these numbers, Lal and many other researchers say that soil carbon sequestration on agricultural land is not the “silver bullet” for controlling global greenhouse gas emissions. But, given the predicted upward trajectory for fossil fuel emissions, it is a critical, relatively easy and immediately deployable tool in the tool chest.
“Putting carbon into land buys us time until no-carbon fuel sources take effect,” Lal explained. “This is a bridge to the future.”
— Georgina Gustin