Excalibur plans to deepen the knowledge on soil biodiversity dynamics and its synergistic effects with prebiotic and probiotic approaches in horticulture, using a multi-actor approach. To pursue this aim, new multifunctional soil microbial inoculants (bio-inocula) and bio-effectors will be tested on three model crops of economic importance (es. tomato, apple, strawberry) under different experimental and open-field conditions across Europe, and the feed-feedback effect of/on native biodiversity monitored. In order to go beyond the multitude of studies on the links between soil biodiversity and plant health, Excalibur will develop a comprehensive strategy of soil management improving the effectiveness of biocontrol and biofertilization practices in agriculture. For this purpose Excalibur plans to: 1) focus on multiscale interactions between plants and belowground organisms to exploit the potential of multifunctional bio-inocula and bio-effectors; 2) optimize the formulation and the application methods of these products based on native soil biodiversity dynamics; 3) develop a strategy to improve the exploitation of soil biodiversity interactions with bio-effectors and bio-inocula by assessing their impacts on crops and biodiversity under contrasting agricultural management practices (conventional, organic) and biotic/abiotic stress conditions; 4) to build a multi-criteria model to assess soil biodiversity status of cropping systems for a more efficient use of bio-effectors and bio-inocula; 5) develop technical tools to monitor the persistence and dispersion of bio-inocula under field conditions for eco-toxicological and agronomical purposes; 6) evaluate the effects of the new strategy on economy, environment quality and ecosystem functions; 7) disseminate results to all stakeholders with a dynamic and comprehensive methodology and encourage the adoption of best practices derived from the new strategy at local, regional and global level.