From May 12–16, 2025, the University of Thessaly hosted the ACTIONr PhD Summer School on Biological Nitrification Inhibition (BNI), bringing together participants from across Europe and beyond, including Austria, Belgium, Germany, Greece, India, Ireland, the Basque Country, New Zealand, the Netherlands, and the UK.The program combined lectures and hands-on training covering plant-derived nitrification inhibitors, ammonia-oxidizing microorganisms, high-throughput screening, amplicon sequencing, and data analysis approaches such as PCA and clustering. Emerging topics such as soil phage therapy and crop breeding for enhanced BNI were also discussed.

The summer school offered a valuable opportunity to explore both the scientific and practical aspects of BNI, with contributions from leading experts in environmental microbiology, soil science, and plant biotechnology. We warmly thank all speakers and participants for their contributions, and extend special thanks to the CropSustaiN BNI Wheat Mission for supporting student travel grants.