Science reports:

When settlers plowed the North American prairie, they uncovered some of the most fertile soil in the world. But tilling those deep-rooted grasslands released massive amounts of underground carbon into the atmosphere. More greenhouse gases wafted into the skies when wetlands were drained and forests cleared for fields. Land conversion continues today, and synthetic fertilizer, diesel-hungry farm machinery, and methane-belching livestock add to the climate effects; all told, farming generates 10% of climate-affecting emissions from the United States each year. Now, Congress would like to turn back the clock and return some of that carbon to the soil.

The Inflation Reduction Act, a broad bill signed into law today, has historic climate provisions, including massive subsidies for clean power and electric vehicles. But lawmakers also included more than $25 billion to expand and safeguard forests and promote farming practices thought to be climate friendly. Those include no-till agriculture and “cover crops,” plants cultivated simply to protect the soil. Researchers, environmental groups, and the farm industry agree that paying and training farmers to adopt those measures will improve soil health and water and air quality. “I think pretty much everyone across the board is pretty happy,” says Haley Leslie-Bole, a climate policy analyst with the World Resources Institute. But how much these practices will slow global warming is unclear.

“It’s probably going to be positive, but how positive we don’t really know yet,” says Jonathan Sanderman, a soil scientist at the Woodwell Climate Research Center. A major factor is whether the U.S. Department of Agriculture (USDA) spends the money on the practices most likely to have climate benefits. Another challenge is measuring and quantifying the reductions, a task complicated by the great diversity of U.S. land and farming practices and the complex biogeochemistry of the carbon cycle. [Continue reading…]