Soils are carbon sinks, storing more planet-warming carbon than the atmosphere and all animal and plant life combined.
But they can also release massive amounts of stored carbon into the atmosphere. Given carbon’s central role in climate change, understanding the forces that govern how soils absorb and release carbon is crucial.
A new study shows that soil age and age-associated changes in mineral content may be the master regulators of carbon cycling in and out of soils and how soil responds to warming. The study was published in Nature Geoscience and is a collaboration between the research group of Professor Asmeret Asefaw Berhe, a group of European scientists and the U.S. Geological Survey.
Soil deposits that differ in age but come from a common source serve as historical records of how soils change over time. These chronosequences, as they’re known in soil science, allow researchers to study the co-evolution of biotic, mineralogical, geochemical and physical processes in soil. Berhe and Sebastian Doetterl, the new study's lead author and a former visiting postdoctoral researcher in Berhe’s lab, said an unusual chronosequence formed by the Merced River led to the new discovery.
“The Merced chronosequence is a unique set of soils that range from very young, 100-year-old deposits to one of the oldest known soils anywhere, a 3-million-year-old soil found in alluvial terraces alongside the Merced River,” Berhe said.