Le vendredi 21 octobre 2016 à partir de 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1
Earthworms contribute to the recycling of organic matter (OM) and participate significantly in the ecosystem services provided by soils. Most studies on the role of earthworms in OM recycling were conducted at the level of the functional groups (epigeic, epi-anecic, anecic strict and endogeic), but their effects at sub-specific levels remain largely unknown. Still, within a functional group, anatomic and physiologic earthworm species traits are different, which should impact OM recycling.
This study aims at determining, within controlled conditions, epi-anecic species differences in OM (i) selection, (ii) ingestion, (iii) assimilation, (iv) excretion and (v) impact on microbial communities. An experiment using microcosms was conducted to compare the impact of four epi-anecic species (Lumbricus rubellus, L. festivus, L. centralis and L. terrestris) on the recycling of three trophic resources (Holcus lanatus, Lolium perenne and Corylus avellana). Measured parameters were taken at several places in the microcosms after 0, 10 and 20 days. Microbial communities were analysed using T-RFLP. Results are discussed taking into account physical and chemical properties of these 3 trophic resources.
Microbial soil organic matter (SOM) biodegradation generates VOCs which could represent a significant loss for soil C sequestration and, in the atmosphere, take part in greenhouse gases production . Our study aims to determine the response of active soil microorganisms to organic amendments applied in farming systems and the consequences on VOC emissions by soil. It is based on the experimental site EFELE labeled SOERE-Allenvi. Just before and up to two months following Pig Slurry (PS) or Methanised Pig Slurry (MPS) amendments, sampling of soil and VOCs using a gas chamber were performed on replicated plots. Active soil microbial diversity was determined by Illumina MiSeq by targeting 16S rRNA (bacteria and archea), and fungal ITS.
Our results indicate a temporal dynamic in the relative composition of the bacterial communities whatever the treatment and that PS amendments specifically led to methanol emissions by soil up to one month following fertilisation.