Nanofertilizers as an alternative to inorganic fertilizers: A review

Abstract

The population of the world is steadily increasing, in contrast to the natural resources which are limited and subjected to further depletion. This induces pressures to develop effective agricultural production systems to meet the growing demands on food and, thus, to mitigate hunger and poverty worldwide. Generally, inorganic fertilizers play a crucial role in maintaining soil fertility and improving crop yield and quality. Inorganic chemical fertilizers are regarded as the main source to supply crops with their needs of nutrients. Proper nutrient management of crops is a major challenge worldwide as it relies predominantly on chemical fertilizers. However, inorganic fertilizers are not only costly but may be harmful and pose risks to human health and have negative impacts on the environment. About half of the amount of applied fertilizers is used by the crop, whereas the remaining fertilizers are lost through leaching and gaseous emissions. The lost nutrients contribute to environmental pollution, global warming and climate change. Moreover, high application rates of chemical fertilizers can deteriorate soil fertility and raise soil salinity and thus lower crop production and quality will occur. This creates a need to invent smart fertilizers that are friendly to the environment, particularly those of high nutrient use efficiency and low leaching potential. Nanotechnology has a vital role in the construction of such fertilizers (nanofertlizers). In these fertilizers, nutrients are bound to nano-dimensional adsorbents (nanomaterials), which release nutrients very slowly as compared to conventional chemical fertilizers. Nanofertilizers are nutrients coated or encapsulated with different types of nanomaterials. They have unique properties like large surface area, slow-release profile, and controlled delivery of nutrients to the targeted sites to meet the nutrient requirements of crops. Nanofertilizers are emerging as a promising alternative to conventional chemical fertilizers, as they offer great opportunities to improve plant nutrition under harsh environments. The benefits associated with the use of nanofertlizers are opening new approaches toward the development of sustainable agriculture. However, further studies are needed for a sound and safe application of nanofertlizers. In this review, researchers’ attempts to produce and use nanofertlizers for sustainable crop production have been presented. The advantages and limitations of the application of these smart fertilizers have also been discussed. Key words: Nanoparticles, Sustainable agriculture, Phytotoxicity, Slow and controlled release, Metal oxides