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Michigan State Soil Carbon Stock Research

Guest Author
Cameron Rudolph, Michigan State University

With support from USDA’s National Institute of Food and Agriculture (NIFA), research at the nation’s Land-grant Universities is a critical element to addressing the challenges climate change poses to agriculture. NIFA’s Agriculture and Food Research Initiative (AFRI), the agency’s flagship competitive grants program, provides important funding to projects working to mitigate the impacts of climate variability. 

Newly published research from Michigan State University is an outstanding example of the work being done with AFRI support. 

A team led by Dr. Bruno Basso has developed a more accurate way to evaluate soil carbon stock changes. Their findings, recently published in Scientific Reports, have significant implications on measuring the actual environmental benefits of regenerative agriculture practices and economic consequences through emerging carbon markets. 

Basso’s team included two members of his laboratory: Ames Fowler, a crop modeling research associate, and Neville Millar, a postdoctoral fellow. Will Brinton, the founder and chief science officer for Woods End Laboratories in Maine, also contributed. 

NIFA national program leader Dr. Jim Dobrowolski said that enhancing agriculture’s sustainability is critical to providing the food, fiber and fuel that supports a growing world population. ”The support that NIFA provides to scientists is crucial to not only improving agriculture but addressing the challenges brought about by climate change,” he said.  

According to a 2022 summary for policymakers from the Intergovernmental Panel on Climate Change, agriculture is responsible for 23% of global greenhouse gas emissions. Given the advances in regenerative agriculture such as cover crops and no-till systems, however, Basso said this presents opportunities to employ meaningful modifications. 

“Agriculture is the main sector affecting soil and landscape management, so improving agricultural management and policy that supports it is essential to reducing greenhouse gas emissions,” he said. “This includes sequestering carbon in the soil, which several private industry and nonprofit organizations have begun valuing.” 

Soils can hold vast quantities of carbon — greater than the atmosphere and vegetation combined — which helps the environment and, more recently, farmers’ bottom lines. Soil carbon incentives and markets have led private companies and nonprofits to pay farmers for sequestering carbon in soil. But many farmers remain skeptical. 

However, the cost of soil sampling, remote sensing image analysis, modeling and other carbon stock assessment methods currently renders the economic benefit tenuous. Basso said farmers are looking for certainty in identifying changes in soil carbon stocks. 

One of the principal challenges, Basso said, has been the adoption of a unified way of measuring soil carbon changes accurately. 

“Science offers an important perspective in the business of carbon markets and agricultural policy,” Basso said. “If we aren’t capturing carbon stock changes appropriately and precisely, then we never develop a true understanding of the effectiveness of our sustainability efforts.” 

To address this challenge, Basso and his team examined the international standard for assessing soil carbon stock changes, which involves repeated fixed-depth soil sampling down to at least 30 centimeters in the same location. 

Using hypothetical 30-centimeter samples taken at three specified times with prescribed changes in soil organic carbon, researchers showed that variations in bulk density result in errors with fixed-depth sampling. 

As more carbon is sequestered in the soil, the bulk density is lessened because more air is present. If carbon is removed, less air is involved, thus making the bulk density greater. Current calculations of soil organic carbon do not factor in this shift in bulk density. 

With an adjustment calculation that considers bulk density called equivalent soil mass (ESM), Basso and his team demonstrated that current methods of soil carbon stock measurement can still be used if ESM is also implemented. This means altering soil depths on measurements depending on bulk density changes. 

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