2019 12 Brouwer The Potential of Nano Fertilizers
Collectively, the evidence provided in this review strongly indicate that nanotechnology has immense potential to improve the efficacy of agrochemical delivery and utilization by crops. As a result of extensive research on plant exposure to nanoparticles, it is clear that ENMs can have detrimental effects at higher concentrations. However, lower dose applications of select ENMs under specific conditions will yield beneficial effects, including enhanced delivery of nutrients, antimicrobial and disease suppression, and insecticidal and herbicidal applications. One very significant development associated with ENMs is that they can significantly reduce the amount of metals/agrichemicals being released into the environment, when compared to conventional formulations. ENM-based soil or foliar fertilization can be achieved through macro- and micronutrient amendments; whereas, the suppression of plant pathogens in infected systems can be attributed to in vivo generation of ROS and activation of antioxidant enzymes by ENMs and other secondary metabolites. Enhanced nutrition through nano-fertilizers could promote inherent plant defense and systemic resistance pathways. Notably, studies often compare ENM effects against untreated controls, with claims of positive outcomes. It is important that all assessment of ENM effects on plants as nano-fertilizers or nano-pesticides involve the corresponding conventional equivalents. Also, in all cases, a cost–benefit analysis of the use of ENMs should be conducted. Without such comparisons, accurate claims of the efficacy and cost effectiveness of nano-enabled agrochemicals cannot be made. Given the small profit margin associated with agriculture/food production, novel strategies will have to be equally effective to conventional approaches, both in terms of economics and efficacy. If developed and applied properly, nano-enabled agricultural approaches such as those described in this review will be a critical component in achieving and sustaining global food security and safety.