Deep soil carbon -- more evidence

The evidence just keeps coming: "There is a lot more deep soil carbon than we once thought," writes Michael Schmidt and 13 of his colleagues in a paper Persistence of soil organic matter as an ecosystem property (eScholarship, 26-9-2012). "Despite their low carbon concentrations, subsoil horizons contribute to more than half of the global soil carbon stocks. In fact, the response of deep soils to land-use change can equal that from the top 30 cm of soil, even though typically only the shallow depths are explicitly represented in models. "Microbial products make up more organic matter in subsoil horizons than do plant compounds. Organic matter in subsoil horizons is characterized by very long turnover times that increase with depth—radiocarbon ages of 1,000 to 10,000 years are common."

AUTHORS: Michael W. I. Schmidt1, Margaret S. Torn2,3*, Samuel Abiven1, Thorsten Dittmar4,5, Georg Guggenberger6, Ivan A. Janssens7, Markus Kleber8, Ingrid Ko¨gel-Knabner9, Johannes Lehmann10, David A. C. Manning11, Paolo Nannipieri12, Daniel P. Rasse13, Steve Weiner14 & Susan E. Trumbore15

1Department of Geography, University of Zurich, 8050 Zu¨ rich, Switzerland. 2Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. 3Energy and Resources
Group, University of California, Berkeley, California 94720, USA. 4Max Planck Research Group for Marine Geochemistry, University of Oldenburg, Institute for Chemistry and Biology of the Marine
Environment, 26129 Oldenburg, Germany. 5Max Planck Research Group for Marine Geochemistry, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany. 6Institute of Soil Science, Leibniz
Universita¨ t Hannover, 30419 Hannover, Germany. 7Department of Biology, University of Antwerp, 2610 Wilrijk, Belgium. 8Department of Crop and Soil Science, Oregon State University, Corvallis, Oregon
97331, USA. 9Lehrstuhl fu¨ r Bodenkunde, Technische Universita¨t Mu¨ nchen, 85354 Freising, Germany. 10Department of Crop and Soil Sciences, Cornell Center for a Sustainable Future, Cornell University,
Ithaca, New York 14853, USA. 11School of Civil Engineering and Geosciences, Institute for Research on Environment and Sustainability, Newcastle University, Newcastle NE1 7RU, UK. 12Department of
Plant, Soil and Environmental Sciences, University of Firenze, 50144 Firenze, Italy. 13Norwegian Institute for Agricultural and Environmental Research, 1432A˚ s, Norway. 14Structural Biology, Weizmann
Institute, 76100 Rehovot, Israel. 15Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.