Phosphorus (P) is a fundamental element for plants. The depletion of the mineral P reserves as a chemical fertilizer will occur suddenly due to the growing world demand for agriculture. In addition, the excessive use of mineral fertilizers causes major dysfunctions of the agrosystem in the medium and long terms. This requires us to quickly discover sustainable alternatives. Large quantities of organic P and inorganic P, adsorbed to soil constituents, represent important reservoirs of P. Exploitation of these P sources, which are not readily available for crops, could be a promising avenue in agriculture. Nematodes are the most abundant animals on Earth. They are ubiquitous and play essential roles in regulating nutrient cycles in ecosystems. Within the rhizosphere, nematodes can greatly improve plant P availability from these poorly-available P sources. However, taking nematodes into account as biological beneficial actors for the increase in plant P availability has so far been largely neglected. Therefore, the mechanisms by which nematodes affect soil P fluxes and the controlling factors, both abiotic and biotic, are unknown. The O-NEMATO-P (Optimizing NEMATOde-driven P availability) project aims to explore the roles of soil nematodes in improving the availability of P for crops from poorly-available sources. The project focuses on ecological processes, mechanisms and controlling factors. We plan to explore and use nematode functional traits to relate the structure of soil nematode communities to P fluxes at the soil-plant interface, without neglecting the usual metrics of community diversity. In order to feed into the agronomic work carried out in agroecology, we are working to develop a "Pho-nem" indicator which will provide information on the capacity of an agricultural practice to intensify the ecological processes involved in the mobilization of P from sources that are not readily available for crops. To achieve this goal, advanced innovative techniques (18O labeling technique, the phytate model, multi-species co-inoculation, and bacterial strains transformed by GFP) will be used in conjunction with modeling and classification techniques by machine learning. The knowledge acquired will provide important fundamental information on the role of soil nematodes on plant P availability from poorly-available P sources. In the current framework of agronomic innovation fueled by agroecology and the ecological intensification of soil functions, our results can be used to design and evaluate the sustainability of agricultural practices by encouraging the exploitation of P sources and thus limiting the use of expensive mineral fertilizers that impact the environment.