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

DIZART, Iowa — ( — When Al Shafbukh cut back on his Iowa fields decades ago and later started growing cover crops, he was looking to save money on fertilizer and reduce erosion. He got these benefits and saw his soil change for the better too: dark, coarse, rich in organic matter, which he says is like “chocolate cake”.

There is another big benefit that everyone benefits from: less tillage and 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 if left undisturbed. This could mean money for participating farmers in the form of carbon offsets — payments companies can make to support carbon storage on farms and, in theory, balance their emissions elsewhere.

“The more carbon you store from the atmosphere with your crops, and the more crops you grow in a year, you offset some of your waste, wasted energy,” said Shalamar Armstrong, assistant professor of agronomy at Purdue University. “Because you’ve accumulated carbon that would have been released (in) into the atmosphere.”

This is an area that legislators, researchers and industry professionals are paying more attention to. The USDA this week announced a $300 million investment to monitor agricultural emissions, including through the establishment of a soil carbon monitoring research network. And US Senators Tina Smith, D-Minnesota, and Todd Young, D-Ind., introduced a bill that Smith said would support the research needed to “properly account for soil carbon stocks.”

The USDA announcement and legislation aims to address the difficult question of how to quantify carbon stored in soil. This is a hurdle that needs to be overcome if the young and rapidly growing market for soil carbon is to avoid the scrutiny and skepticism directed at carbon credit markets.

“The science part (carbon credits) is really lagging behind, especially when it comes to things like monitoring, reporting and verification,” said Kristel Zobisch, deputy director of policy for Climate 180. soil, but really any solution to remove carbon on land.”

Armstrong tried to solve this problem. He runs a lab where researchers study how agricultural management affects soil carbon in different landscapes. He and others at Purdue studied soil samples over 40 years old, comparing different types of tillage and cover crops, to determine their long-term impact on carbon storage. It can take years of field research, careful laboratory chemistry, and a lot of expensive equipment to solve this problem.

He hopes his accurate calculations will help farmers make decisions that will allow them to get decent incentives to sequester carbon while maintaining existing profits.

But other scientists fear that even if farmers are paid to store carbon in the soil, it won’t solve a bigger problem: Carbon markets often don’t work.

For offsets to be legal, they must meet four criteria. They must store the carbon that would otherwise be emitted; they must be validated against the data; they must be immediate (planting a tree that can grow in 20 years will not help); and they need to be durable, says John Sterman, professor of management at MIT.

Improved quantification of soil carbon stocks through research can make biases more verifiable, but does not account for other factors. For example, many farmers lease the land they work on and cannot guarantee that the carbon stored on their land will last for several decades if someone else farms the land.

Barbara Haya, director of the Berkeley Carbon Trading Project at UC Berkeley, has been working on a study that she says shows that the impacts of carbon offset projects are typically overestimated, and sometimes greatly.

“Carbon trading is a mechanism that has failed miserably over the past 20 years, one that we really need to get away from,” Haya said.

US Rep. Jared Huffman, D-Calif., introduced a bipartisan bill last month to support farmers to improve soil health with incentives that don’t necessarily have to do with the carbon market. He said that farmers in his area also talked about the benefits of regenerative methods and that many would be interested in participating in carbon markets with “reliable” accounting systems. But he added that those hoping for serious action to combat climate change should not rely solely on offsets.

“In my opinion, this is really not a silver bullet,” Huffman said. “I think offsets are inherently sketchy.”

Some farmers are cautious.

Brad Wetley, an Indiana farmer who partners with Armstrong, has been trying methods that require less tillage for several years and has been planting cover crops such as rye for several years. He’s happy with the way his current fields look – “It looks like you’re doing something” to contribute to sustainability, he said – but he’s still weighing his options with possible carbon credit contracts, doing the math and waiting to see if the price will be right, since many offset agreements can last several years.

“I’m going to be working maybe one or two fields at a time, and as I learn more, I’ll hopefully incorporate more carbon or carbon credits into the work,” he said.

Schafbuch, for his part, is skeptical of carbon credits but would be enthusiastic about regenerative farming, no matter the upfront cost. He said he was a trailblazer in the face of neighbors who laughed and assumed he would “end up broke”, but he proved them wrong.

“I am convinced that if you do it right, anyone can do it,” he said.


Associated Press journalist Joshua Bickel contributed to this report from Fowler, Indiana.


Follow Melina Walling on Twitter @MelinaWalling.


The Associated Press’ climate and environmental coverage receives support from several private foundations. Learn more about the AP Climate Initiative here. AP is solely responsible for all content.

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