As of my last knowledge update in January 2022, nanofertilizers were an emerging field of research and development, and further advancements and regulatory developments may have occurred since then.1
References
1Sahoo PK. Nanotechnology in agriculture: A paradigm shift in sustainable farming. In: Satyannarayana B, Barwant MM, eds. Advances in Chemical and Biological Sciences. Vol II. Bhumi Publishing; :4-18.