Agricultural management affects the response of soil bacterial community structure and respiration to water-stress

International audience; Soil microorganisms are responsible for organic matter decomposition processes that regulate soil carbon storage and mineralisation to CO2. Climate change is predicted to increase the frequency of drought events, with uncertain consequences for soil microbial communities. In this study we tested the hypothesis that agricultural management used to enhance soil carbon stocks would increase the stability of microbial community structure and activity in response to water-stress. Soil was sampled from a long-term field trial with three soil carbon management systems and was used in a laboratory study of the effect of a dry wet cycle on organic C mineralisation and microbi…

Relationship between microbial diversity and soil organic matter turnover

International audience

High microbial diversity promotes soil ecosystem functioning

ABSTRACT In soil, the link between microbial diversity and carbon transformations is challenged by the concept of functional redundancy. Here, we hypothesized that functional redundancy may decrease with increasing carbon source recalcitrance and that coupling of diversity with C cycling may change accordingly. We manipulated microbial diversity to examine how diversity decrease affects the decomposition of easily degradable (i.e., allochthonous plant residues) versus recalcitrant (i.e., autochthonous organic matter) C sources. We found that a decrease in microbial diversity (i) affected the decomposition of both autochthonous and allochthonous carbon sources, thereby reducing global CO 2 e…

Influence of microbial diversity on soil organic carbon dynamics highlighted by a 13C-labelling technique

Soil organic matter (SOM) represents the main pool of carbon within the biosphere, estimated at roughly twice that in atmospheric CO2. In agrosystems, organic amendments are common to maintain soil C stocks. However, recent studies have revealed that these practices can lead to a priming effect, corresponding to enhanced release of CO2 into the atmosphere, due to over-mineralisation of soil organic carbon. Therefore, appropriate decisions regarding organic input management require better understanding of the biogeochemical cycles related to SOM dynamics. As soil microorganisms are major actors in SOM turnover, their diversity is likely to influence SOM dynamics. In this context, the relatio…

Relation entre mode d’usage agronomique, diversité microbienne et turn-over des matières organiques dans le sol

Affiche, résumé; International audience

How do drought and rain events impact soil microbial communities greenhouse gas production?

Affiche, résumé. Session GC: Microbes in the Changing Environmenl: Global Climate Change and Soil under Human Impact; International audience

Influence de la qualité biochimique des résidus végétaux sur les processus de minéralisation et les communautés bactériennes impliquées