Biosynthesized metallic nanoparticles as fertilizers: An emerging precision agriculture strategy

Nanofertilizers increase efficiency and sustainability of agricultural crop production. Due to their nanosize properties, they have been shown to increase productivity through target delivery or slow release of nutrients, thereby limiting the rate of fertilizer application required. Nanofertilizers can be synthesized via different approaches ranging from physical and chemical to green (biological) synthesis. The green approach is preferable because it makes use of less chemicals, thereby producing less chemical contamination and it is safer in comparison to physicochemical approaches. Hence, discussion on the use of green synthesized nanoparticles as nanofertilizers is pertinent for a sustainable approach in agriculture. This review discusses recent developments and applications of biologically synthesized metallic nanoparticles that can also be used as nanofertilizers, as well as their uptake mechanisms for plant growth. Toxicity concerns of nanoparticle applications in agriculture are also discussed.