Can nanotechnology deliver the promised benefits without negatively impacting soil microbial life?

Abstract

Nanotechnology exploits the enhanced reactivity of materials at the atomic scale to improve various applications for humankind. In agriculture, potential nanotechnology applications include crop protection and fertilization. However, such benefits could come with risks for the environment: non-target plants, plant-beneficial soil microbes and other life forms could be impacted if nanoparticles (nanomaterials) contaminate the environment. This review evaluates the impact of the major metallic nanoparticles (Ag, ZnO, CuO, CeO2 , TiO2 , and FeO-based nanoparticles) on soil microbes involved in agricultural processes. The current literature indicate that in addition to population and organismal-scale effects on microbes, other subtle impacts of nanoparticles are seen in the nitrogen cycle, soil enzyme activities, and processes involved in iron metabolism, phytohormone, and antibiotic production. These effects are negative or positive, the outcome being dependent on specific nanoparticles. Collectively, published results suggest that nanotechnology portends considerable, many negative, implications for soil microbes and, thus, agricultural processes that are microbially driven. Nonetheless, the potential of plant and soil microbial processes to mitigate the bioreactivity of nanoparticles also are observed. Whereas the roots of most terrestrial plants are associated with microbes, studies of nanoparticle interactions with plants and microbes are generally conducted separately. The few studies in actual microbe-plant systems found effects of nanoparticles on the functioning of arbuscular mycorrhizal fungi, nitrogen fixation, as well as on the production of microbial siderophores in the plant rhizosphere. It is suggested that a better understanding of the agro-ecological ramifications of nanoparticles would require more in-depth interactive studies in combined plant-microbe-nanoparticle systems.

Fortification of micronutrients for efficient agronomic production: a review

“…Directly, it may act as signals for the cellular activities of proteins involved in disease resistance in cereals (Shirasu et al 1999;Datnoff et al 2007). Indirectly, Zn may act by influencing pathogen growth via the stimulation of the activity of biocontrol bacteria producing antimicrobial metabolites such as salicylic acid, siderophores, and the antibiotic, 2,4-diacetylphloroglucinol (Duffy and Defago 1999;Dimkpa et al 2012aDimkpa et al , 2015a, causing membrane damage, hyphal structural damage, oxidative stress, or reduction of siderophore production (He et al 2012;Dimkpa et al 2013a, b;Dimkpa 2014;Zabrieske et al 2015). Notably, the acidification of the environmental to a pH range that might be nonoptimal for pathogen growth seems to be another mechanism by which Zn may indirectly play a role in soil-borne crop disease control (Dimkpa et al 2013a, b).…”

Revisiting fertilisers and fertilisation strategies for improved nutrient uptake by plants

“…Despite its immense benefits, nanotechnology also comes with risks because, similar to all chemical processes, it could have undesirable effects on non-target organisms, including plants and plant-associated soil microbes, depending on NP, dose applied and the biological species (Dimkpa et al 2012b;Dimkpa 2014;Gardea-Torresdey et al 2014). Accordingly, any large-scale adoption of nanotechnology for agricultural purposes must be supported by rigorous research to provide a better understanding of its agro-ecological ramifications, including the plant-specificity of the activity of the different nanomaterials, as well as any potential, dose-dependent, biotoxicity.…”

Emerging and Established Technologies to Increase Nitrogen Use Efficiency of Cereals

“…An example is producing fertilizers with formulations that include more than one nutrient. Although plants would preferentially transport more than one and inhibit the uptake of others [125,126] …”

“…An example is producing fertilizers with formulations that include more than one nutrient. Although plants would preferentially transport more than one and inhibit the uptake of others [125,126], synergism in nutrient uptake has been demonstrated for N [127] and other nutrients [128,129] with proper formulations.…”