Can rock dust be a climate solution for agriculture?

Agriculture generates nearly a quarter of the world’s greenhouse gas emissions, which has spurred scientists to seek ways of reducing farming’s contributions to climate change. In FERN’s latest story, published with Yale Environment 360, Susan Cosier reports that researchers have found that dusting crop fields with pulverized rock such as basalt can supercharge the chemical process that sequesters carbon in the soil.

Rocks naturally remove carbon dioxide from the air — about a billion tons annually. As Cosier writes, adding rock dust to farmland speeds up that chemical process, binding carbon pulled from the air with minerals in farm fields and locking it up for potentially thousands of years in the soil. The development is timely, especially with the Biden administration’s emphasis on making agriculture carbon neutral.

If applied to croplands globally, rock dust — such as basalt, which is plentiful — could theoretically help suck an estimated 2 to 4 billion tons of carbon dioxide from the air every year. That’s between 34 and 68 percent of the global greenhouse gas emissions produced by agriculture annually.

Scientists are testing different rock amendments, in different quantities, on hemp in upstate New York, alfalfa and olives in California, corn in Illinois, sugarcane in Australia, and soybeans in Ontario. So far, the results look promising: Carbon uptake on California plots doubled once rock dust was applied — a surprise, considering the crops were grown under the driest conditions in the state’s history. Applying rock dust even has the potential to increase farmers’ bottom lines. In test plots, it raised corn and alfalfa yields by up to 30 percent.

“This is an incredibly exciting technology that has a lot of wins for society,” Benjamin Houlton, a Cornell University professor of ecology and evolutionary biology, told Cosier. “And, frankly, we could deploy this very quickly.”