Recent Advances in Nano-Fertilizers: Synthesis Strategies, Mechanistic Insights, Environmental Implications, and Emerging Applications for Enhancing Nutrient Use Efficiency in Sustainable Agriculture Systems

The rapid increase in global population, coupled with the ongoing pressures of climate change and land degradation, has intensified the need for more efficient and sustainable agricultural practices. Conventional fertilizers have played a pivotal role in boosting crop productivity over the past century; however, their inefficiencies and environmental consequences have become increasingly evident. It is widely reported that a substantial portion of applied nutrients—often exceeding 50%—is lost to the environment through leaching, runoff, volatilization, and fixation in soil matrices, leading to serious ecological issues such as eutrophication, greenhouse gas emissions, and soil degradation. In this context, nanotechnology has emerged as a promising interdisciplinary approach capable of revolutionizing agricultural nutrient delivery systems. Nano-fertilizers, defined as materials that either contain nutrients in nanoscale dimensions or utilize nanostructured carriers for controlled nutrient release, offer enhanced nutrient use efficiency, targeted delivery, and reduced environmental losses. Their unique physicochemical properties, including high surface area-to-volume ratio, tunable reactivity, and the ability to interact with biological systems at the molecular level, enable improved plant uptake and utilization. This paper presents a comprehensive and in-depth discussion of nano-fertilizers, encompassing their classification, synthesis strategies, mechanisms of action, and practical applications in agriculture. Additionally, the review critically examines their advantages, potential risks, and future perspectives, with a focus on their role in advancing sustainable agricultural systems.