We all eat! This activity truly unifies all humans. However, the industrialization of agriculture in many parts of the world has disconnected society from the massive scale of agriculture and its immense environmental impacts. Consumers choose fresh produce based on taste and appearance, and are not typically thinking about the amount of fertilizer that was added to the soil, the energy use and corresponding greenhouse gas emissions required to make that fertilizer. So, the link between the luscious head of lettuce and eutrophic waterways that damage aquatic ecosystems and contaminate our drinking water sources is imperceptible. Despite this, the perpetuating system-wide inefficiencies in agriculture (that will only exacerbate with continuing global population growth) must be addressed.
Technological innovation fueled the expansion of the agriculture and food system to become what it is today. For example, mechanization, irrigation, and the astounding ability to make nitrogen fertilizer from air and H2, all vastly increased production. We are now turning to technological innovation again; this time leveraging the very small – nanotechnology – to address inefficiencies that have adversely impacted the environment and human health for too long.
Environmental engineers are uniquely poised to address the challenges of unsustainable agriculture because we study soil, air, and water systems as well as their interconnectedness. We are trained to study pollution and complex processes within natural systems, while also having the skillsets necessary to develop solutions. The authors of a recent Nature Nanotechnology article “Guiding the design space for nanotechnology to advance sustainable crop production” are environmental engineers with a common expertise in nanotechnology. The recent emergence of nano-enabled solutions to advance agriculture motivated our critical analysis. We approached our analysis with cautious excitement knowing the impact – both positive and negative – that designing at the nano-scale can have on ecosystems and human health. While nano-enabled solutions in crop production can increase agrochemical use efficiencies, protect crops from pests and disease, and increase crop resilience, we believe it is prudent to consider the added environmental and economic costs that designing at the nano-scale potentially introduces to achieve these benefits. The balance of benefits and impacts determines the sustainability of the approaches proposed to combat global agriculture and food system challenges.
Our analysis assessed whether or not nano-enabling crop production "makes sense" when we consider these trade-offs. We focus on three applications where engineered nanomaterials (ENMs) are currently being pursued: soil amendments, seed coatings, and foliar sprays. The upstream environmental and human health impacts from synthesis of ENMs are weighed against the relevant benefit for each application: reduced N input, increased germination, and increased yield. Our analysis reveals that seed coatings and foliar applications of ENMs are the most promising, likely due to the targeted nature of the treatment. Within each application, 5-9 different ENMs are considered. The greatest gains include a 15-fold increase in percent seed germination and 25-fold increase in precent yield for the best performing ENMs compared to conventional methods. The associated environmental impact (as embodied energy) to achieve these performance improvements ranges from a 10-fold reduction to a 100-fold increase. Our findings offer guidance for future research by identifying applications and specific ENMs with the greatest potential to sustainably advancing crop production. Early adoption of the most promising approaches will lead to overall economic and environmental benefits, enabling nano solutions to have a macro, global impact.