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Determining water and gas flows in soils, and thus physical and chemical environment for organisms, soil structure is essential for soil functioning. Appropriate soil structure management is needed for a sustainable agricultural production and environment protection. However, given its high variability in space and in time, partly due to climate and agricultural practice impacts, soil structure is still poorly defined and measured. New tools are used to describe soil structure in 3D), but they are still hard to access and too expensive to be commonly used. More in situ and quantitative methods are needed for this fragile element of soil. We thus propose the use of acoustic emissions (AE) to capture a new dimension of soil structure by passively listening to soil structural changes. Passive AE are produced in soils by various processes such as liquid bridge rupture, crack development, grain friction, etc. AE productions in soils are then due to particles movement; the hypothesis is that AE could be a useful tool to characterize the soil structure dynamics. The aim is to develop AE-based metrics that would complement destructive sampling of soil aggregates and allow in situ assessment of soil structural status and dynamics under physical and biological processes of evolution. This would contribute to the development of a tool to easily and objectively determine soil structure in the field, and allow a better soil structure management in an agricultural context. Our results should also help understand soil structure dynamic and contribute to improve soil structure dynamics modelling.
I had my first experience in soil science research during my internship to obtain an Agricultural Engineer degree (Bordeaux Sciences Agro). I was then working on the digital soil parent material map of the French Brittany, and it confirmed my interest in soil science. In 2009, I decided to go further with a PhD, during which I worked on soil evolution modelling at the landscape and century scales, at high resolution (2m), focusing on soil organic carbon dynamics and soil redistribution under water and tillage processes. In 2013, I pursued with a post- doc (US INFOSOL, INRA), working on the first high resolution (90 m) 3D soil mapping for France, in the framework of the GlobalSoilMap project. In 2014, I was hired as researcher on a permanent position at INRA to work on soil structure modeling from the plot to the field scale. I am currently working on the potentiality of passive acoustic emissions (AE) by soils to characterize soil structure change; through a project I am leading. The first results are promising, and thanks to the AgreenSkills program, I had the opportunity to develop this very innovative topic by working with the STEP group (ETH, Zurich). The aim is to develop AE-based metrics that would complement destructive sampling of soil aggregates and allow in situ assessment of soil structural status and dynamics under physical and biological processes of evolution. This would contribute to the development of a tool to easily and objectively determine soil structure in the field, and allow a better soil structure management in an agricultural context. Our results should also help understand soil structure dynamic and contribute to improve soil structure dynamics modelling.
Grossel, A., Nicoullaud, B., Bourennane, H., Lacoste, M., Guimbaud, C., Robert, C., Hénault, C., 2016. The effect of tile-drainage on nitrous oxide emissions from soils and drainage streams in a cropped landscape in Central France. Agriculture, Ecosystems and Environment, 230, 251-260.
Rabot, E., Lacoste, M., Hénault, C., Cousin, I., 2015. Using X-ray Computed Tomography to Describe the Dynamics of Nitrous Oxide Emissions during Soil Drying. Vadose Zone Journal, 14 (8). Doi: 10.2136/ vzj2014.12.0177.
Lacoste, M., Mulder, V. L., Richer de Forges, A., Martin, M. P., Arrouays, D., 2016. Evaluating large-extent spatial modeling approaches: A case study for soil depth for France. Geoderma Régional, 7 (2), 137-152.
Lacoste, M., Viaud, V., Michot, D., Walter, C., 2015. Landscape-scale modelling of erosion processes and soil carbon dynamics under land-use and climate change in agroecosystems. European Journal of Soil Science, 66 (4), 780 - 791.
Lacoste, M., Minasny, B., McBratney, A. B., Michot, D., Viaud, V., Walter, C., 2014. High resolution 3D mapping of soil organic carbon in a heterogeneous agricultural landscape. Geoderma, 213, 296-311.