How do microbes “tuck away” carbon? The role of microbes in physical soil organic carbon stabilization
A grand challenge for mankind is to fight climate change, which involves both reducing and reverting CO2 emissions. Soils store much more carbon (C) than the atmosphere, and it is microorganisms that govern whether C compounds remain in the soil, or whether they are disintegrated back to CO2. An important mechanism of long-term C storage is the physical stabilization of organic matter within the soil structure, meaning that C can be “hidden” from its decomposers in the complex matrix of soil aggregates, but the processes involved are not well understood.
We have studied the dynamic process of microbial soil aggregate formation, and the nature of fungal “gluing” exudates, with help of different synchrotron light techniques at MAX IV laboratory, and in collaboration at the Canadian Light Source. We have combined these micro-scale studies with experiments at field scale, where we probed a soil aggregate structure gradient and investigated the amount of spatio-physical inaccessible C in relation to its aggregate stability. Understanding the mechanisms of physical C stabilization is the basis to identify soil cultivation techniques which foster this process, and to be able to increase the C sink potential of our soils by convincing agriculture and forestry policy makers.