How the soil microbiome could be enhanced by vermicomposting strategies : an experimental case.

Food security depends primarily on growers which intrinsically rely on the capacity and condition of soils to deliver functions and services that are mostly provided by healthy soil microbiome. The need for alternative solutions to fertilizers and pesticides and better sustainable soil management surges into the farming community as production cost and soil depletion increase. Vermicomposting has been accepted as an environmentally beneficial waste stabilization process for transforming organic wastes into high-value organic amendment. In the framework of soil bioremediation and soil food web modeling, vermicomposting is considered as an evolving sustainable technology providing soil microorganisms stored into their gut microbiota. In this study we aim to highlight the key role of earthworms, especially the potential of Eisenia Fetida, as significant indigenous microorganisms (IMO) accumulators and an alternative solution in remediating soil microbiome and restoring soil functions. The experimentation takes place into a vineyard in the southeast of France that applies agroecological practices for 5 years and has a non-optimized system (no irrigation, no fertilizers, no pesticide treatments). The vermicomposting bioreactors have been made with the Soil Food Web method of Dr. Elaine Ingham. Vermicomposting was a necessary prior stage for one year to develop the microorganism’s diversity and obtain the second and third soil trophic levels. The earthworms were fed with local organic matter in order to inoculate their gut microbiota with IMO. Once mature, the earthworms’ substrates were removed in order to extract and breed the IMO produced by the earthworms into a food-enriched oxygenated water, called Vermicompost Oxygenated Tea (VOT). From April to June 2023, the VOT were used as foliar sprays to protect plants from diseases and applied to soil. Preliminary results show that VOT reduced 3 times disease of leaves vines(p<0.001), reduced retention time of water (P<0.001) and increased soil penetrability (P<0.001) for the experimental plot compared to agroecological and control plots. 

Céline Basset, PhD student Cnam University, ESDR.

contribution with Quentin Lambert, PhD ecology at CEA (Atomic Energy Comission).