Climate Research
How Soil Stores Carbon Dioxide
"The carbon binds to minerals that are just a few thousandths of a millimeter in size – and it accumulates there almost exclusively on rough and angular surfaces", Prof. Ingrid Kögel-Knabner explains, TUM chair of soil science. The theory is that the rough mineral surfaces provide an attractive habitat for microbes. These are able to convert carbon and help binding it to the minerals. "We discovered veritable hot spots with a high proportion of carbon in the soil", says Cordula Vogel, the lead author of the study. "Furthermore, new carbon binds to areas which already have a high carbon content." These carbon hot spots are, however, only found on about 20 percent of the mineral surfaces. Previously, it was assumed that carbon is evenly distributed in the soil. "Thanks to our study, we can now pin-point the soil that is especially good for sequestering CO2", Kögel-Knabner continues. "The next step is to include these findings in carbon cycle models."
The sample material used by the team was loess, a fertile agricultural soil found in all parts of the world – making it a very important carbon store. The researchers were able to take ultra-precise measurements using the NanoSIMS mass spectrometer. This instrument allowed them to view and compare even the most minute soil structures.


Carbon binds | to specific rough mineral surfaces known as hot spots (yellow areas).
In recognition of her work on the formation of soil organic matter and its central role in the terrestrial carbon cycle, as well as for her academic achievements and her outstanding teaching, Prof. Ingrid Kögel Knabner has been awarded the Order of Merit of the Federal Republic of Germany (Bundesverdienstkreuz am Bande) in January 2014. (© Technical University Munich, AcademiaNet)