Abbas Shoukat*
Institute of Plant Nutrition and Soil Science, Kiel University, Hermann-Rodewald-Str. 2, 24118 Kiel, Germany
*Corresponding author: ashoukat@plantnutrition.uni-kiel.de
Nanofertilizers (NFs) represent a transformative approach in sustainable agriculture by integrating nanoscale carriers and smart delivery systems into plant nutrition. This review synthesizes recent advances in four major categories of NFs: macro-nanofertilizers (N, P, K), micro-nanofertilizers (Zn, Fe, Mn, Cu, B, Mo), nano-biofertilizers (microbial and polysaccharide-based), and smart nanofertilizers (controlled-release and stimuli-responsive). We highlight their unique mechanisms of action, including multiple uptake pathways (root, foliar, and stomatal), controlled nutrient release, improved bioavailability, and modulation of plant physiology at molecular and metabolic levels. A particular focus is given to their role in mitigating abiotic stresses salinity, drought, heat, and nutrient deficiencies through regulation of ion homeostasis, antioxidant defense, osmolyte accumulation, and photosynthetic stability. Evidence from cereals, horticultural crops, and biofortification programs indicates that NFs not only enhance nutrient-use efficiency (NUE) and yields but also improve nutritional quality of grains, thereby addressing both food security and hidden hunger. Environmental assessments reveal that, compared with conventional fertilizers, NFs substantially reduce leaching, volatilization, and greenhouse gas emissions, while potential ecological risks remain associated with nanoparticle persistence, transformation, and impacts on soil microbial diversity. Despite these advantages, limitations such as nanotoxicity, high production costs, and insufficient multi-year field validations pose challenges to widescale adoption. Emerging opportunities lie in safe-by-design formulations using biodegradable carriers, stress-specific nanoformulations, and integration with precision agriculture and digital farming. Overall, NFs offer a paradigm shift toward climate-smart and resource-efficient agriculture, but responsible innovation, regulatory frameworks, and farmer-oriented validation are essential for realizing their global potential.