And now researchers have found that soil texture also plays an important role in how readily carbon is sequestered underground: Coarse soils are substantially more vulnerable to releasing their carbon than previously believed.
Many people think of the world’s forests or atmosphere as containing the largest planetary stockpile of carbon, said Iain P.
But it’s not locked up there forever: Soil is also home to microbes, which readily break down organic compounds and release their carbon into the atmosphere.
But an open question in soil science is whether soil texture—its fineness or coarseness—also affects the likelihood of carbon being transferred out of underground storage, said Hartley.
The digital records, obtained from the World Soil Information database, included such measurements as the soil’s pH, its carbon content, its ability to hold on to certain ions, and its percentage of clay minerals.
Fine-textured soils tend to consist of tiny agglomerations of organic matter and minerals in which carbon is essentially shielded from microbes, said Hartley, but such clusters ought to be vulnerable to disassociation at high temperatures.
The team also found that carbon storage in coarse-textured soils declined more rapidly with temperature than previously estimated.
These results, which were published in November in Nature Communications, are valuable because they highlight the types of soils most likely to relinquish their carbon to the atmosphere.
And that’s an important quantity to determine, said Keith Paustian, a soil scientist at Colorado State University in Fort Collins who was not involved in the research.