Persistence of Soil Organic Matter: It Takes an Ecosystem
Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. However, whereas some SOM persists for millennia, other SOM decomposes readily, according to phenomena that we currently do not understand. This limits our ability to predict how soils will respond to climate change. DOE scientists from Lawrence Berkeley National Laboratory have recently demonstrated that SOM molecular structure alone does not control SOM stability; in fact, environmental and biological controls predominate, such as interdependence of compound chemistry, reactive mineral surfaces, climate, water availability, soil acidity, soil redox state, and the presence of potential degraders in the immediate environment. In other words, the persistence of soil organic carbon is primarily not a molecular property, but an ecosystem property. The authors also propose ways to include this understanding in a new generation of experiments and soil carbon models that will improve predictions of the SOM response to global warming.
Schmidt, M. W. I., M. S. Torn, S. Abiven, T. Dittmar, G. Guggenberger, I. A. Janssens, M. Kleber, I. Kogel-Knabner, J. Lehmann, D. A. C. Manning, O. Nannipieri, D. P. Rasse, S. Weiner, and S. E. Trumbore. 2011. “Persistence of Soil Organic Matter as an Ecosystem Property,” Nature 478, 49-56. (DOI: 10.1038/nature10386)