The techniques that regenerative farmers use vary with soil, climate and crop. They start from the understanding that healthy soil teems with more than a billion microorganisms per teaspoon and the behavior of those organisms facilitates hardy plant life. To fertilize their fields, regenerative farmers use nutrient-rich manure or compost, avoiding as much as possible chemical fertilizers and pesticides, which can kill huge quantities of organic matter and reduce plants’ resilience. They don’t like to till the soil, since tillage increases carbon emissions into the atmosphere. Some farmers combine livestock, cover crops and row crops sequentially on the same field, or plant perennials, shrubs and even trees along with row crops. Leaving soil bare during off-seasons is taboo, since barren soil easily erodes, depleting more carbon from the soil; regenerative farmers instead plant cover crops to capture more carbon and nitrogen from the atmosphere.

Until the advent of synthetics in the late 1800s, fertilizer consisted chiefly of carbon-rich manure or compost. But synthetic fertilizers contain no carbon, and as their use spread along with tillage practices to incorporate them, soil carbon content declined. The process accelerated after World War II, when America’s nitrogen-based munition plants were converted into nitrogen-based fertilizer factories. Most agricultural colleges still teach soil fertility chiefly as an exercise in applying inorganic chemical fertilizer, while overlooking soil’s biological role (and its carbon content). Despite soil’s connection to climate change, carbon sequestration in soil was never mentioned in the 1997 Kyoto Protocol, which set down broad greenhouse gas emission reduction targets for the world’s nations.

California began an initiative in 2015 to incorporate soil health into the state’s farm and ranch operations. Some of the pioneering studies showing regenerative agriculture’s benefits have been carried out at the Marin Carbon Project, on a self-proclaimed carbon-farming ranch in the pastoral reaches of Marin County 30 miles northwest of San Francisco. A four-year study there showed that a one-time application of compost caused an increase in plant productivity that has continued ever since, and that the soil’s carbon content grew year after year, at a rate equivalent to the removal from the atmosphere of 1.5 metric tons of carbon dioxide per acre annually.

Whendee Silver, an ecosystem ecologist at the University of California at Berkeley who is the project’s lead scientist, calculated along with a colleague that if as little as 5 percent of California’s grangelands was coated with one-quarter to one-half inch of compost, the resulting carbon sequestration would be the equivalent of the annual greenhouse emissions of nine million cars. The diversion of green waste from the state’s overcrowded landfills would also prevent it from generating methane, another potent greenhouse gas.

Some scientists remain skeptical of regenerative agriculture, arguing that its impact will be small or will work only with certain soils. It also faces significant obstacles, such as a scarcity of research funding and the requirements of federal crop insurance, which frequently disqualifies farmers who plant cover crops. But fears that the Trump administration would squelch government support for it so far have proved unfounded.

Consider the experience of Willie Durham, a soil health specialist at the federal Department of Agriculture’s Natural Resources Conservation Service in Temple, Tex. What led Mr. Durham to regenerative agriculture was his discovery while a Texas state agronomist of the “pesticide treadmill”: “People I’d known for a long, long time would ask me, ‘If nothing is changed in our agricultural system, why are we using two to three times as much fertilizer to accomplish the same thing?’ It got to where we spent so much on inputs that we didn’t make any profit.”

Now Mr. Durham teaches regenerative agriculture to farmers in Texas and Oklahoma. The farmers he inspires are predominantly young, not yet habituated to conventional agriculture — he estimates that about 10 percent of his students use the information, and the percentage is increasing. In a region where rainfall is usually precious, some conventional soil has become so lifeless that it absorbs as little as half an inch of water per hour, Mr. Durham said, while regenerative fields can absorb more than eight inches an hour.

Mr. Durham’s farmers are learning a lesson that resonates throughout human interactions with the natural world: People reap more benefit from nature when they give up trying to vanquish it and instead see it clearly, as a demanding but indispensable ally. Because of carbon’s climate change connection, we’ve been conditioned to think of it as the enemy, when in fact it’s as vital to life as water. The way to make amends is to put it back in the soil, where it belongs.