The EU-funded ACTIONr project addressed the critical challenge of nitrogen (N) management in agriculture, recognising its essential role in food production and its contribution to environmental degradation when nitrogen is used inefficiently. Traditional farming practices relying on synthetic nitrogen fertilizers have led to nitrogen losses, environmental impacts and pressure on soil microbial communities. With a focus on Thessaly, a major agricultural region in Greece, ACTIONr aimed to improve nitrogen use efficiency (NUE) and mitigate environmental impacts linked to soil nitrogen cycling.
The main objectives of ACTIONr were to: (1) explore the cellular mechanisms of action of synthetic and biological nitrification inhibitors (NIs); (2) develop synthetic microbial communities to screen NI activity under ecologically relevant conditions; (3) assess the impacts of NIs on soil microbiota and greenhouse gas emissions; and (4) generate experimental evidence supporting the development of safer and more efficient NI-based fertilisation strategies. These objectives were addressed through close collaboration between the University of Thessaly (UTH), the Centre National de la Recherche Scientifique (CNRS; former École Centrale de Lyon group) and the University of Vienna (UNIVIE), combining complementary expertise in microbial nitrogen cycling.
Implemented as a Horizon Europe Twinning project, ACTIONr strengthened the scientific capacity and international integration of UTH through staff exchanges, advanced training activities and joint research. The project introduced advanced experimental and analytical approaches that were not previously available at UTH, including multi-omics workflows, synthetic microbial communities for nitrifier research, fast-track screening assays for nitrification inhibitors, and miniaturised soil microcosm systems enabling realistic assessment of microbial and nitrogen-cycle responses. These capacities are now embedded in the research activities of UTH and support ongoing and follow-up projects.
At the scientific level, ACTIONr advanced understanding of how synthetic and biological nitrification inhibitors interact with key microbial groups involved in nitrogen cycling at cellular, community and soil scales. At the institutional level, the project improved the international visibility of UTH, strengthened its participation in European research networks and competitive funding schemes, supported the development of a sustainable project portfolio, and established durable collaboration structures with its twinning partners, including a Joint PhD Platform. In line with global sustainability priorities, ACTIONr contributed to promoting responsible nitrogen use and environmental stewardship, consistent with the United Nations Sustainable Development Goals.
