European Journal of Sustainable Agroecosystems

Background: Nitrogen (N) is the most important limiting nutrient in cereal cropping systems, but standard urea fertilizer’s nitrogen uses efficiency (NUE) seldom surpasses 30-40%, causing huge economic losses and environmental problems from its volatilization and leaching as well as nitrous oxide emissions. Nano-urea — a foliar fertilizer with only about 4% nitrogen — is introduced as a more efficient solution which is able to reduce traditional nitrogen inputs by as much as 25%. Nevertheless, there is no unification of main aspects of nano-urea functioning as its agricultural, molecular and biophysical principles can be found in different articles. 
Aim: This review summarizes existing data in order to develop a unified theoretical framework connecting nano-urea foliar absorption and ChlF response.
Sources: The structured investigation of Scopus, PubMed, Google Scholar, SpringerLink and Web of Science (2000–2025) assisted by reports from institutions resulted in the acquisition of 32 studies that satisfied established requirements for selection. Main findings. Nano urea can help obtain equal as well as slightly improved yields and health of cereals when used in combination with soil N without total substitution. When compared to other fares, nano-urea shows the best results in terms of supplementation of the dosages from 25% to 33% of what should be used for normal functioning (8,9,11).
What still needs to be studied: The absence of standardized ChlF methods, along with a lack of reports on kinetic constants (Vmax, Km) of foliar nano-urea, controls that display N-responsiveness, and genotype × dose × environment interactions.
Conclusion: The use of nano-urea can be best approached as a matter of improving efficacy by highlighting its mechanism of action that needs to be studied through uptake kinetics coupled with phenotyping based on fluorescence.