PhD thesis in Soil Sciences : Study of the links between biodiversity, soil structure and soil functioning

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

Scientific context and objectives of the thesis 

Environmental forcing from human activities alters the soil's organo-mineral matrix, soil organisms, and the biotic-abiotic interactions that underpin the ecological functions of soils necessary for healthy ecosystems. Preserving soils and the biodiversity they support, and restoring their functions when degraded, are therefore major challenges for all soils worldwide. However, numerous challenges and scientific gaps need to be addressed to tackle this issue.

Soil biodiversity plays a crucial role in maintaining soil structure and associated functions, as soil organisms and biological activity influence porosity and aggregation through the decomposition of organic matter, root activity, exudates, and bioturbation. Recent advances in 3D imaging have improved our understanding of the links between soil structure, organic matter dynamics, and flux transfers. However, the effect of biodiversity and trophic and non-trophic interactions on soil physical structure remains poorly characterized, as the data enabling these characterizations are fragmented, limited to single sites, or focused on isolated soil properties (physical and biological soil properties are still rarely characterized at the same sites). Conversely, bioturbation morphologies depend on pedoclimatic conditions and soil management practices, and we do not know to what extent these different morphologies can impact soil functions such as water infiltration and gas transfer. Furthermore, soil structure is still frequently considered static, without taking into account the lifespan of the biostructures created and the seasonal variations they undergo.

This thesis aims to contribute to answering the following question: what is the impact of biological actors (e.g., roots, soil meso- and macrofauna), as agents of soil stabilization and restructuring, on soil functioning? This thesis project will be carried out within the framework of the PEPR Sols Vivants, whose mission is to produce knowledge on the role of soil organisms and their multiple interaction networks in the multifunctionality of soils, for a diversity of soil types, uses and management methods, in order to meet the challenge of preserving and improving soil health.

Work environment

The successful candidate will be hosted within the Info&Sols Research Unit (INRAE ​​Orléans), under the supervision of Isabelle Cousin (PhD Director) and Marine Lacoste (Co-supervisor). The PhD will also be supervised by Guénola Péres (UMR SAS, Co- director) and Maha Chalhoub (BRGM, Co-supervisor). The Info&Sols unit's scientific project is structured around three main research areas: 1) Soil status, functioning, and monitoring; 2) Soil quality, health, ecosystem services, and impacts; and 3) Environmental data management.

Main missions

The PhD candidate will be tasked with exploring the links between soil biodiversity, soil structure, and soil function, focusing on water and gas transfer properties. Specifically, he/she will be responsible for:

• Designing a conceptual model linking transfer properties and biodiversity characteristics.

• Acquiring data on the physical properties of soils and the characteristics of soil biodiversity across metropolitan France (fieldwork conducted during a campaign in spring 2027, and laboratory experiments).

• Processing the acquired data to extract indicators characterizing the soil.

• Creating and sharing a dataset compliant with FAIR principles.

• Analyzing the dataset to deduce links between biodiversity and soil function.

Application procedures

Funding for the PhD is secured. The PhD supervisors will select two to three candidates after reviewing their applications and conducting interviews. The selected candidates will be interviewed in person in Orléans or Tours (France) on May 11^th or 12^th 2026, by a jury from the EMSTU Doctoral School, which will establish the final ranking. Only candidates residing abroad at the time of the interview will be permitted to participate via videoconference. The successful candidate will be enrolled at the University of Orléans, within the EMSTU Doctoral School.

travel within metropolitan France is expected in spring 2027. 

Occasional travel within France and abroad is also planned within the framework of the PEPR Sols Vivants project or for scientific communications.

Training and skills

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

How to apply

Please apply only via the doctoral school website:

https://collegedoctoral-cvl.fr/as/ed/voirproposition.pl?site=CDCVL&matricule_prop=70746