The PSG research group develops innovative research on soil organic matter since 2003. We use modern analytical tools such as isotopic 13C analysis, in bulk soils (CHN/IRMS), in gases evolved from soils and in molecular extracts from soils (GC-C/IRMS). We characterize organic matter with molecular tools: GC/MS of soil chemical fractions (lignin, sugars, lipids), flash pyrolysis/GC/MS, 13C solid state NMR. The combination of isotopic and molecular tools gives access to the dynamics of organic matter at the molecular level. We study this dynamics on long term experimental fields of the french long term observatory (SOERE) and on many experimental sites around the world.


Our work changed the paradigm of chemical recalcitrance as main controlling factor of SOM persistence

Processes affecting SOM stabilisation on a molecular level

by combining chemical characterization of SOM at the molecular level with the study of its location in the soil matrix, and its dynamics through the use of carbon isotope analyses (Dignac et al., 2005; Mendez-Millan et al., 2010; Thévenot et al., 2010).



We were one of the first groups showing that soil carbon is mostly root carbon


(Rasse et al., 2005) because  it is affected preferentially by all stabilisation processes due to its location within the mineral phase.





Moreover, our work has led to the recognition of erosion as important controlling factor of the fate of fire-derived black carbon

Fire on strong slopes producing pyrogenic C susceptible to erosion (c) V. Chaplot

by combining extensive fieldwork and chemical SOM characterisation (Rumpel et al., 2006; 2009).





Thanks to the combination of molecular tools in microbiology and soil organic matter research we were one of the first groups showing that microbial decomposition functions are impacted by reduced diversity (Baumann et al., 2013).



We also pioneered research on composition and turnover of organic matter in deep soil horizons, an important compartment, completely neglected at former times. We changed the paradigm of its high stability (Sanaullah et al., 2011, 2016) and showed using isotopic analyses at nanoscale that there are contrasting organic matter types stabilised by mineral interactions in top- and subsoil horizons (Rumpel et al., 2015).




Baumann, K., Dignac, M.-F., Rumpel, C., Bardoux, G., Sarr, A., Steffens, M., Marron, P.A., 2013 : Soil microbial diversity affects soil organic matter decomposition in a silty grassland soil. Biogeochemistry, 114, 201-212.

Dignac M.-F., Bahri H., Rumpel C., Rasse D.P., Bardoux G., Balesdent J., Girardin C., Chenu C., Mariotti A., 2005 : Carbon-13 natural abundance as a tool to study the dynamics of lignin monomers in soil: an appraisal at the Closeaux experimental field (France). Geoderma, 128, 1-17.

Mendez-Millan, M., Dignac, M.-F., Rumpel, C., Rasse, D.P., Derenne, S., 2010: Molecular dynamics of shoot vs root biomarkers in an agricultural soil estimated by natural abundance 13C labelling. Soil Biology and Biochemistry, 42, 169-177.

Rasse, D.P., Rumpel, C., Dignac, M.-F., 2005 : Is soil carbon mostly root carbon? Mechanisms for a specific stabilisation. Plant and Soil, 269, 341-356.

Rumpel, C., Chaplot, V., Planchon, O., Bernadoux, J., Valentin, C., Mariotti, A., 2006: Preferential erosion of black carbon on steep slopes with slash and burn agriculture. Catena, 65, 30-40.

Rumpel, C., Ba, A., Darboux, F., Chaplot, V., Planchon, O., 2009 : Erosion budget of pyrogenic carbon at meter scale and process selectivity. Geoderma, 154, 131-137.

Rumpel, C., Baumann, K., Remusat, L., Dignac, M.-F., Barré, P., Deldicque, D., Glasser, G., Lieberwirth, I., Chabbi, A., 2015 : Nanoscale evidence of contrasted processes for root-derived organic matter stabilization by mineral interactions depending on soil depth. Soil Biology and Biochemistry, 85, 82-88.

Sanaullah, M., Chabbi, A., Leifeld, J., Bardoux, G., Billiou, D., Rumpel, C., 2011 : Decomposition and stabilization of root litter in top- and subsoil horizons: what is the difference? Plant and Soil, 338, 127-141.

Sanaullah, M., Chabbi, A., Maron, P.-A., Baumann, K., Tardy, V., Blagodatskaya, C., Kuzyakov, Y. and Rumpel, C., 2016: How do microbial communities at different soil depths respond to root litter addition under field conditions? Soil Biology and Biochemistry 103, 28-38.

Thévenot, M., Dignac, M.-F., Rumpel, C., 2010 : Fate of lignins in soils : a review. Soil Biology and Biochemistry, 42, 1200-1211.