Ohio State University soil scientist Rattan Lal says the agricultural soils of the world have the potential to soak up 13 percent of the carbon dioxide in the atmosphere today—the equivalent of scrubbing every ounce of CO2 released into the atmosphere since 1980. The claim is a bold one, but researchers around the globe are digging up evidence that even modest changes to farming and ranching can have a major impact on carbon sequestration.
Some growers have already embraced an approach known as regenerative agriculture, which aims to boost soil fertility and moisture retention through established practices such as composting, keeping fields planted year-round, reducing tillage, and increasing plant diversity. Since these strategies can also significantly increase the amount of carbon stored in the soil, some agricultural researchers are now building a case for their use in combating climate change. This year seven international conferences will examine soil’s potential to sequester greenhouse gases.
Lal first came to the idea of soil as a powerful carbon sink (pdf) not through an interest in climate change, but rather out of concern for the land itself and the people who depend on its productivity. While carbon-depleted soils tend to be dry and prone to erosion, carbon-rich soil is dark, crumbly, fertile, and moist. In the 1970s and 1980s, Lal was studying soils in Africa so devoid of organic matter that the ground had become like hardened cement. There he met Roger Ravelle, a pioneer in the study of global warming. When Lal made a despairing remark about the impoverished soil, Ravelle suggested that the carbon had moved into the atmosphere. “I told Roger I didn’t know where it had gone; I just wanted to put it back,” Lal recalls.
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