How much carbon can farmers store in their soil? Nobody’s sure.

Advocates say the long-awaited farm bill could help fix that.

a group of people look at a man standing in a deep hole in the dirt

Dirt, it turns out, isn’t just worm poop. It’s also a humongous receptacle of carbon, some 2.5 trillion tons of it — three times more than all the carbon in the atmosphere.

That’s why if you ask a climate wonk about the U.S. farm bill — the broad, trillion-dollar spending package Congress is supposed to pass this year (after failing to do so last year) — they’ll probably tell you something about the stuff beneath your feet. The bill to fund agricultural and food programs could put a dent in the country’s greenhouse gas emissions, some environmental advocates say, if it does one thing in particular: Help farmers store carbon in their soil.

The problem is, no one really knows how much carbon farmers can store in their soil.

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