Miss Solène Quero¹, Mrs Sophie Cornu¹, Mr Nithavong Cam¹, Mr Jérôme Balesdent¹, Mr Adrien Duvivier¹, Mr Daniel Borschneck¹, Mrs Isabelle Basile-Doelsch¹

¹Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Aix-En-Provence, France

Organo-mineral interactions are known to play a key role in stabilizing organic matter (OM) in soils because bonds between organic compounds and mineral surfaces minimize microbial degradation of organic compounds. A better understanding of the mechanisms that control the OM stabilization is therefore necessary, especially of those responsible for the destabilization of the nano-organo-mineral complexes following a forest to crop transition. Indeed, it is assumed that the mineral surfaces are not stable in time, but subject to weathering that leads to the formation of organo-mineral nano-complexes, called ” Short Range Order minerals- Organic Matter” (SRO-OM) here after. The hypothesis is that most of the stabilized soil organic matter are consist int these complexes. The idea is to show that the latter are destabilized by a land use change.

In that frame, a pair site approach consisting in two adjacent plots with different land uses, forest and vineyard respectively, was chosen. Poorly differentiated soils on granite were sampled at Plan de la Tour (83), in the Maures Massif (France). The two plots are located on the same agricultural terrace. Analyses of aerial photos and cadastral data shows that these two plots have experience the same land use for at least 100 years. Two soil profiles, 15 m apart, were described and sampled on pit. Chemical, particle-size distribution and mineralogical characterizations were performed to determine the degree of similarity of the two soils. The distribution of organic carbon contents and stocks in soils is highly contrasted between the two land uses. A tangential filtration physical fractionation method allowed to isolate the SRO-OM in the 10kDa – 200 nm size ranges of some horizons in order to understand if the differences in organic carbon contents and stocks observed in both profiles were related to differences in nature or quantity in these SRO-OM.

Biography:

I graduated as an engineer, specializing in environmental sciences, from a leading engineering school of Agronomy and Food Industries (Nancy 2017, FRANCE).

During my last year of study, I did a 6-month internship at CIRAD, in Reunion Island. The purpose was to evaluate the carbon stocks of Reunion

Island’s soils, using mid-infrared spectroscopy.

Then, I have started a thesis at CEREGE (Aix-en-Provence 2017, FRANCE), under the supervision of Isabelle Basile-Doelsch (INRA) and Sophie Cornu (INRA). I am working on the evolution of organo-mineral interactions at nanoscale in soils, after a forest to crop transition.