Dr Alix Vidal¹, Tobias Lenhart², Dr. Marie-France  Dignac³, Dr. Justine Barthod⁴, Philippe Biron⁴, Patricia Richard⁵, Valérie Pouteau³, Véronique Vaury⁴, Dr. Thierry Bariac⁴, Dr. Cornelia Rumpel⁴

¹TU München, Lehrstuhl für Bodenkunde, Freising, Germany, ²Ingenieurbüro PGA, Planung Gutachten Analytik GmbH, Altdorf, Germany, ³UMR Ecosys, Thiverval-Grignon,  France, ⁴UMR iEES-Paris, Paris,  France, ⁵Laboratoire des Sciences du Climat et de l’Environnement, Paléocéan, Saint-Aubin,  France

The agricultural use of organic amendments, such as (vermi)composts provides a sustainable method to incorporate nutrients and organic carbon in soils and to potentially mitigate climate change. However, (vermi)composting production and application to soil generates high quantities of greenhouse gases, which can be reduced using additives such as clay minerals during the production of co-(vermi)composts. Little is known about the impact of co-(vermi)composts on plant growth and the soil carbon cycle. In the present study, we investigated (1) the effect of co-(vermi)composts on root and shoot biomass production of two contrasted plants and (2) the transfer of plant-derived carbon into different soil compartments. We continuously labeled with ¹³C plants of ryegrass and haricot, grown in microcosms filled with soil amended with four different composts: vermicompost, compost, vermicompost produced with 30% montmorillonite or compost produced with 30% montmorillonite. Six weeks after sowing, shoots, roots, rhizospheric and bulk soils were separated and the biomass of shoots and roots were quantified. Carbon, nitrogen and δ¹³C values were obtained for plant and soil samples. To depict organo-mineral interactions and the incorporation of ¹³C at the root-soil interface, two samples were selected for nano-scale secondary ion mass spectrometry analyses (secondary ion images of ¹²C, ¹³C, ¹²C¹⁴N, ¹⁶O and ⁵⁶Fe¹⁶O). Our results showed that co-(vermi)composting increased root and shoot biomass production of both plants compared with (vermi)compost. The plant biomass was significantly reduced in the presence of vermicompost compared to co-vermicompost, especially for ryegrass (around six-fold lower for roots and shoots). The rhizosphere represented a hotspot for plant-derived carbon compared to bulk soil, as reflected by the higher δ¹³C values in this compartment, especially with co-(vermi)compost. The use of clay minerals during (vermi)composting has a beneficial impact on plant growth, likely reflecting the structuring, as well as organic carbon and nutrient adsorption capacities of clay minerals.

Biography:

Dr. Alix Vidal, born 1989 in Epernay, France

7 ISI-papers with 39 citations, h-index is 4

Professional and academic career

->since 2016 – Research Assistant (Akademischer Ratin auf Zeit), Chair of soil science, Technical University of Munich

->Sep. 2016 – Dr. in Soil science, University Pierre et Marie Curie (UPMC), France

->2013 – 2016 – Doctoral candidate at UMR Metis, UPMC, France

->2013 – Dipl. Agricultural engineering, Ecole Supérieure d´Agriculture d´Angers, France

->2013 – Dipl. Agricultural engineering, Escola Superior de Agricultura « Luiz de Queiroz », São Paulo, Brazil

->2007-2013 – Study of agricultural engineering, France/Brazil

Research areas

->Soil biogeochemistry

->Biotic factors (litter type and earthworms) controlling soil organic matter decomposition

->Interactions between plant, soil and microorganisms in the rhizosphere

->Influence of organic amendments on soil characteristics

->Use of carbon stable isotope (13C) to trace carbon flows in soils

->Combination of classical quantitative (EA-IRMS, GC-MS, NMR spectroscopy) and spectromicroscopic (NanoSIMS) and imaging techniques (TEM, SEM)