The Dirty Way to Feed More People and Help Stop Climate Change

Building soil fertility increases yields and helps farmland store more carbon.

(Photo: Martin Poole/Getty Images)

Jun 28, 2016· 2 MIN READ
Tove Danovich is a journalist based in Portland, Oregon.

Modern agriculture has not been kind to the soil. Since intensive agriculture took off in the 1950s, farming in the United States has emphasized harvest yields over environmental (or taste) concerns. Then, with the Green Revolution in the 1960s, we exported those ideas around the world. Yet over the last decade, it’s become apparent that treating the soil to maximize yield can strip both our food and the soil of important nutrients.

On average, 70 percent of all land has degraded soil, according to the Natural Resources Conservation Service. In an overview on land degradation, the NRCS wrote, “The productivity of some lands has declined by 50% due to soil erosion and desertification.” In Africa, poor soil may have caused yield reductions of as much as 40 percent. Globally, loss caused by degradation “costs the world about $400 billion per year,” according to the NRCS.

But in the fight against climate change and global hunger, lowly soil may be our greatest resource.

Schoolchildren learn that trees and plants turn “bad” air into “good,” and adults know that deforestation exacerbates rising levels of greenhouse gases. “But those trees have roots,” pointed out Ephraim Nkonya, a senior research fellow at the International Food Policy Research Institute who specializes in land management and natural-resource use in sub-Saharan Africa and Central Asia. “We see trees above the ground and get fixated on their importance,” Nkonya said. But stopping climate change is less about planting more trees to make up for losses owing to deforestation than about taking better care of the land we have. Changing agricultural practices to focus on better land management and decreased deforestation could reduce nearly a third of carbon emissions.

Plants—all plants, not just trees—draw carbon out of the air to help them grow, and what they don’t need is drawn through their roots into the soil. Eighty percent of all terrestrial carbon resides in the soil, according to a 2012 Nature article by two members of the Department of Natural Resource Ecology and Management at Iowa State University. While two-thirds of carbon dioxide emissions come from burning fossil fuels, a third comes from soil organic carbon loss “due to land use change such as the clearing of forests and the cultivation of land for food production,” the authors wrote.

Other studies support Nkonya’s findings. One published in March in Frontiers in Ecology and the Environment analyzed a 700-year-old indigenous soil management system from West Africa that yields a substance the authors call “African dark earths.” Adding a mix of charcoal and kitchen scraps “transforms highly weathered, infertile, yellowish-to-red tropical...into black, highly fertile, carbon-rich soils,” wrote lead author Dawit Solomon of Cornell University.

“Anything that you can plant in the red soil...can grow well in the black soil, but plantain, banana, and cocoa will not grow well in the red soil. The black soil is the chief of all soil around here!” local farmers told researchers, according to the study. Compared with unmanaged soils nearby, the amended “dark earths” have higher levels of phosphorous and nitrogen and store 200 to 300 percent more organic carbon—which is good for both yields and, if replicated on large amounts of farmland, curbing climate change.

“Land that’s cleared is cleared to make room for agriculture,” Nkonya said. If productivity is low, he explained, farmers need more land to feed themselves and make a living. “We’ve ignored that for a long time, and it was a big mistake.”

Those struggling to make ends meet often don’t have the luxury of considering the environment when deciding what farming methods to use. But in the dark earths study, Solomon notes that 24 percent of farm household income for those participants in the African community came from food grown in this hyper-rich soil. Good soil doesn’t just help make better food and cleaner air; it can make money too.

Nkonya said that until recently, most of the people focusing on soil were biophysical scientists who liked to talk about the pH of the soil or specific land-management practices and how they could help the environment. “Who cares about those things?” he said of farmers struggling to make a living. Now people are looking at how much money can be made from helping the soil improve and giving that information to farmers who can benefit from the paychecks and better growing conditions. Financial gain from soil management is becoming even more direct for some farmers. Carbon credit programs like those employed by Australia, the World Bank, and the National Farmers Union allow farmers who reduce carbon emissions to sell their “credits” to big polluters like General Motors that want to offset their emissions.

“If you speak money,” Nkonya said, “everybody pays attention.”