Farm fields don't just feed us. They store carbon. But the big question is how much

When Al Schafbuch cut back on plowing in his Iowa fields decades ago and later started cover crops, he wanted to save money on fertilizer and reduce erosion. He reaped those benefits and saw his soil change for the better, too: a dark, coarse, rich organic matter that he said looked like "chocolate cake."

There's another big payoff that benefits everyone: working less land and growing more cover crops can help farmers store more planet-warming carbon in their fields. More plants take in more carbon dioxide and soil microbes exhale less carbon when undisturbed. That can mean money for participating farmers in the form of carbon offsets—payments companies can make that encourage carbon storage on farms and, in theory, offset their emissions elsewhere. (MELINA WALLING)