Stored soil carbon is a hot commodity as corporations search for solutions to reduce their carbon footprint. One option is purchasing carbon credits from agricultural producers. But how that carbon will be measured on U.S. farmland has yet to be determined, according to Soil Scientist Katie Lewis, Texas A&M AgriLife Research and Extension.

Lewis, who has been studying carbon since graduate school, said there are two possibilities.

"The big debate is will we take the approach of using models to estimate carbon storage, 'If we use these certain practices, there's the potential to store this much carbon in our soil?'" Lewis said.

"There are established models that predict the amount of carbon that's going to be stored in the soil after implementing certain practices like no-till or strip-till or implementing cover crops or crop rotations."

Lewis recently spoke with Farm Press following her presentation at Texas Alliance for Water Conservation annual field day in Lubbock.

Physical measurements

The other approach is physically measuring the amount of soil carbon being stored or sequestered. "That would require someone, and we don't exactly know who, to go out and measure carbon in the soil, to monitor over time, how much carbon is being captured from the atmosphere and stored in the soil," Lewis said.

For producers who farm in the harsh conditions of the Texas Plains, the modeling approach would likely be most profitable, Lewis said.

"It's hard over time to build large amounts of carbon compared to other regions across the U.S. that receive more rainfall and have cooler temperatures, and it all goes back to the amount of carbon that we're able to produce through our crops. The more biomass we produce, the more carbon that's being captured from the atmosphere and the greater potential for that carbon to be stored in the soil."

Carbon career

Carbon sequestration is not a new topic to Lewis nor as a society, "We've had this conversation before," she said.

"As a master's and Ph.D. student, I was looking at different organic materials considered waste materials. But we were evaluating them as soil amendments to look at their potential to provide nutrients to the soil and as a potential means of storing additional carbon in the soil. So, a big focus of my research as a graduate student was looking at carbon cycling and carbon storage."

Her advisor, Frank Hons, focused a major part of his career on carbon, she said. "He was working with carbon in the late 90s, early 2000s, during the time of the Kyoto Protocol and Clean Air Act, and all of that really goes back to a carbon focus.

"So, this isn't the first time we've talked about carbon, but I think it has a slightly different spin because we have been talking about soil health for the last five to six years. And when you think about it, carbon is what's driving soil health."

Lewis credits carbon for stimulating microbial activity and adding to the chemical composition of the soil, "because it's improving the ability of the soil to hold onto nutrients.

"From a physical standpoint, carbon is the main driver behind aggregate formation. It's acting as a glue,  binding soil particles together and it's creating healthier soils, not just from a biological standpoint but both a chemical and physical standpoint."

Watch this video to learn more. In Part 2 of Lewis' conversation with Farm Press, she will discuss the challenges of accurately measuring soil carbon.

To learn more about what Economist Darren Hudson has to say about the carbon credit market, click the links below: