Nanofertilisers: Agronomic promise and the need for a fit-for-purpose EU regulatory framework

Nanofertilisers have emerged as one of the most visible and rapidly expanding domains within nano-enabled agriculture, yet their agronomic maturity and deployment readiness remain uneven. This review provides a boundary-setting and critical synthesis of nanofertilisers at the interface of agronomy, environmental behaviour, and governance, with a specific focus on the European Union. The analysis combines bibliometric mapping of the research landscape with an interpretative review of technological evolution, agronomic evidence, environmental and system-level uncertainties, and regulatory implications. Bibliometric results show that nanofertiliser research has expanded rapidly and diversified beyond material formulation towards agronomic, environmental, sustainability-oriented, and governance-related themes. However, technological sophistication and agronomic consolidation have not progressed at the same pace. The evidence base remains dominated by controlled-condition studies, while field validation is still limited and uneven across formulation classes. Nano-urea and related nano-N systems currently represent the most mature field-oriented trajectory, whereas phosphorus-oriented nano-hydroxyapatite systems occupy an intermediate position and more complex nanocarrier or hybrid platforms remain largely pre-field. The review further shows that the future relevance of nanofertilisers cannot be judged solely on the basis of formulation performance, because uncertainties concerning fate, persistence, bioavailability, non-target interactions, combined exposures, scalability, and cost remain substantial. From a European perspective, the main limitation is not only scientific or technological immaturity, but the absence of a coherent fit-for-purpose pathway capable of linking material characterisation, agronomic validation, environmental evidence, and regulatory positioning. The review concludes that progress in the EU will require more selective archetype-based development, stronger standardisation, wider field validation, and tiered evidence strategies aligned with Safe and Sustainable by Design principles.