Nanotechnology has revolutionized many sectors, including agriculture, where nanoparticles are used for targeted delivery of agrochemicals, nano-fertilizers, and pest control agents. However, the unintentional release of engineered nanoparticles (ENPs) poses potential risks to soil health, crop productivity, and food safety. Understanding the behavior of NPs in the complex agricultural environment is essential. It has emerged as a transformative force in agriculture, offering innovative solutions to longstanding challenges related to crop productivity, nutrient use efficiency, pest control, and environmental sustainability. ENPs typically defined as materials with at least one dimension under 100 nm, are increasingly incorporated into agrochemical formulations such as nano-fertilizers, nano-pesticides, and soil conditioners due to their enhanced reactivity, targeted delivery potential, and controlled release properties (Bouhadi et al., 2025; Kah et al., 2018; Servin et al., 2015). However, as their application expands, so does the concern about their unintended introduction into agricultural ecosystems through diverse pathways, including irrigation with contaminated water, nanoparticle-laden biosolids, atmospheric deposition, and direct incorporation into soil or plant systems (Figure 1). Once in the environment, ENPs interact dynamically with soil components, plant roots, microbial communities, and water sources, triggering complex transport and transformation behaviors that are often governed by three principal factors: particle size, surface coating, and environmental aging (Wang et al., 2023; Ma and Wang, 2010; Shiv et al., 2024). Particle size fundamentally influences nanoparticle mobility, uptake, and toxicity, as smaller particles possess a greater surface area-to-volume ratio and tend to exhibit higher chemical reactivity and bioavailability, facilitating their translocation across biological membranes and into edible plant tissues (Nawaz, 2025; Rico et al., 2011; Servin et al., 2015). Surface coatings intentionally added during synthesis to stabilize nanoparticles modulate their physicochemical interactions with the environment by altering surface charge, hydrophobicity, and aggregation behavior; standard coatings like polyethylene glycol (PEG), citrate, and natural organic matter have been shown to either mitigate or enhance toxicity depending on their composition and environmental context (Wikipedia, 2025; Keller et al., 2013; Ahmed et al., 2021). Meanwhile, ecological aging, encompassing a suite of physical, chemical, and biological processes, transforms ENPs over time through sulfidation, oxidation-reduction, dissolution, and microbial interaction (Mondejar-Lopez et al., 2024). These transformations can reduce or amplify the toxicity of ENPs, impact on their bioavailability, and generate new nano-species or by-products whose environmental and toxicological profiles are not well understood (Shiv et al., 2024; Shao et al., 2022; Lowry et al., 2012).

The toxicity of ENPs to plants varies by nanoparticle type and environmental concentration, with observed effects ranging from inhibited seed germination, root elongation, and photosynthesis, to increased oxidative stress and altered nutrient uptake (Bouhadi et al., 2025; Singh et al., 2021; Ma et al., 2010; Dimkpa et al., 2012). Moreover, ENPs have been shown to disrupt soil microbial communities, suppress enzymatic activities crucial to nutrient cycling, and impair beneficial plant-microbe symbioses, thereby threatening soil health and fertility (Nawaz, 2025; Ge et al., 2011; Raliya et al., 2015). While laboratory studies have contributed significantly to our understanding of nanoparticle behavior and effects, they often fail to replicate the complexity of real agricultural environments shaped by variable soil chemistry, climate conditions, and co-exposure to other agrochemicals. Long-term field studies remain sparse, and significant knowledge gaps persist regarding the chronic effects of low-level ENP exposure, the cumulative impact of mixed nanoparticle systems, and their interactions with climate-induced stressors. As such, we must advance our mechanistic understanding of how particle size, surface modifications, and aging processes influence ENP transport and toxicity across trophic levels and over time (Figure 2). This knowledge is essential not only for the accurate risk assessment and regulation of nanotechnology in agriculture but also for guiding the design of next-generation ENPs that are both effective and environmentally benign, aligning technological innovation with the principles of ecological safety and sustainable food production (Wikipedia, 2025; Bundschuh et al., 2018; Rico et al., 2011).

The toxicity and transport of nanoparticles (NPs) in agricultural ecosystems are increasingly scrutinized due to their widespread use and potential environmental impacts. Among the most studied NPs are iron oxide (Fe₃O₄ or Fe₂O₃) and zinc oxide (ZnO), both of which are widely applied in fertilizers, pesticides, and soil amendments due to their nutrient-delivering and antimicrobial properties. However, their interactions with soil biota, plants, and water systems raise concerns. While generally considered less toxic, iron oxide nanoparticles (IONPs) can induce oxidative stress and alter root morphology and microbial community structure at higher concentrations (Kumar et al., 2021). They tend to aggregate in soil, reducing mobility but posing risks through prolonged exposure and accumulation. In contrast, ZnO nanoparticles are more soluble and mobile, and their dissolution releases Zn²⁺ ions, which can disrupt plant physiological processes, impair photosynthesis, and inhibit root elongation (Dimkpa et al., 2012). Moreover, ZnO NPs have shown significant toxicity toward beneficial soil microbes, including nitrogen-fixing bacteria and mycorrhizal fungi, impacting nutrient cycling and plant health (Raliya and Tarafdar, 2013). Transport mechanisms of these NPs in soil involve advection, diffusion, and interaction with organic matter and clay minerals. The size, surface charge, and coating of nanoparticles greatly influence their mobility and bioavailability. For instance, smaller particles with high surface area are more likely to penetrate plant root systems and enter the food chain (Servin et al., 2015). Environmental factors such as pH, ionic strength, and the presence of natural organic matter further modulate NP behavior, enhancing their dispersion or promoting aggregation. Other NPs like titanium dioxide (TiO₂) and silver (Ag) nanoparticles also exhibit varying degrees of phytotoxicity and persistence, with TiO₂ typically showing low toxicity but potential for accumulation, and Ag NPs being notably toxic to both plants and microbes even at low concentrations (Wang et al., 2016). Hence, while nanoparticles offer innovative tools for sustainable agriculture, their unintended ecotoxicological effects and complex transport dynamics warrant careful risk assessment and regulation to avoid long-term environmental consequences (Schlagenhauf et al., 2015).

Nanoparticles (NPs) have become increasingly prevalent in agriculture due to their unique properties, such as increased surface area, reactivity, and the ability to interact with plant systems, soil, and pests. Their application in agriculture spans various uses, from enhancing plant growth and soil fertility to controlling pests and diseases. The classification of nanoparticles used in agriculture is based on their size, material composition, and intended functional role in agricultural applications. Understanding the different types of nanoparticles and their classifications is essential to assess their effectiveness, environmental impact, and potential toxicity. Nanoparticles can be classified in several ways, but the most common categorizations are based on their material composition, size, and shape (Figure 3).

Nanoparticles enter soil through irrigation, biosolids, or atmospheric deposition. Their mobility is influenced by physicochemical properties and environmental conditions (Figure 4). The Key Transport Factors are Particle Size (smaller particles exhibit greater mobility), Surface Coating (alters surface charge and interaction with soil colloids), and Soil pH and Organic Matter (affect aggregation and adsorption).

The toxicity of nanoparticles (NPs) to plants and soil microorganisms is closely linked to their concentration, as these materials can exhibit either beneficial or detrimental effects depending on the dose and exposure conditions. At low concentrations, specific nanoparticles such as zinc oxide (ZnO), iron oxide (Fe₂O₃), and titanium dioxide (TiO₂) may enhance plant growth by improving photosynthesis, nutrient uptake, and stress tolerance. However, at higher concentrations, these same nanoparticles can become phytotoxic, leading to oxidative stress, inhibition of seed germination, stunted root elongation, and reduced chlorophyll content (Rastogi et al., 2017; Hsueh et al., 2015). Similarly, soil microbial communities are susceptible to nanoparticle exposure. For instance, silver nanoparticles (AgNPs), even at relatively low levels, can disrupt microbial biomass, inhibit nitrogen-fixing bacteria, and alter the structure and function of key microbial populations responsible for nutrient cycling (Ge et al., 2011; Chhipa, 2017). The dose-dependent nature of nanoparticle toxicity underscores the importance of assessing environmental concentrations and application practices to balance their agricultural benefits while minimizing ecological risks.

Surface coatings play a pivotal role in modulating the behavior, stability, and toxicity of engineered nanoparticles (ENPs) used in agriculture (Table 4). The surface modification of nanoparticles with organic or inorganic coatings can significantly influence their interactions with plants, soil, and microorganisms, affecting their overall environmental impact. Coatings, such as polymers, surfactants, or natural substances like humic acids and proteins, can improve nanoparticle dispersion in aqueous environments, preventing agglomeration and ensuring more uniform distribution in soil and plant tissues (Vural Kaymaz et al., 2023). For example, polyethylene glycol (PEG) coatings can enhance the solubility and bioavailability of nanoparticles, facilitating their uptake by plant roots and improving nutrient delivery (Djanaguiraman et al., 2024). Moreover, surface coatings can reduce the toxicity of nanoparticles by altering their surface charge and reactivity. Coating with biocompatible materials can decrease the release of toxic ions from metal-based nanoparticles, such as silver or copper, thereby reducing oxidative stress and DNA damage in plants and soil microorganisms (Auffan et al., 2009). Additionally, surface coatings can enhance the stability of nanoparticles under environmental conditions, preventing their aggregation and ensuring their persistence in agricultural systems. However, the type of coating, its thickness, and its chemical composition are critical factors that determine the efficacy of the nanoparticles for farm applications. While specific coatings may reduce toxicity and enhance nanoparticle uptake, others may increase their environmental persistence, leading to potential long-term ecological effects (Keller et al., 2013). Thus, optimizing surface coatings is essential for balancing the benefits of nanoparticle use in agriculture by minimizing potential risks to plant health, soil fertility, and environmental sustainability. Surface coatings (e.g., polymers, natural organic matter) can modulate nanoparticle behavior, stabilize against aggregation, reduce or enhance toxicity, and alter plant uptake.

Nanoparticles undergo physical, chemical, and biological transformations: Sulfidation- AgNPs convert to Ag2S, reducing toxicity, Oxidation/Reduction- Alters surface reactivity, and Biotransformation Microbial interactions lead to new nano-species (Figure 6). The aging and transformation of engineered nanoparticles (ENPs) in soil are critical factors that influence their environmental behavior, bioavailability, and potential toxicity in agricultural systems. Upon their introduction into soil, nanoparticles undergo various physical, chemical, and biological processes that alter their size, shape, surface properties, and reactivity over time. These transformations are influenced by a range of soil characteristics, such as pH, organic matter content, ionic strength, and microbial activity, all of which can modify the fate and impact of nanoparticles on plants and soil ecosystems (Scown et al., 2010). Aging refers to the gradual changes in nanoparticle characteristics as they interact with soil components and environmental factors, such as water and temperature fluctuations. For example, metal-based nanoparticles like silver (AgNPs) and copper oxide (CuO NPs) are prone to oxidation or sulfidation in the presence of sulfur-containing compounds and oxygen, which can result in the formation of less toxic metal sulfides or oxides (Bystrzejewska-Piotrowska et al., 2009). This process can reduce their reactivity and toxicity, potentially mitigating their impact on soil microorganisms and plants. On the other hand, some transformations can increase nanoparticle toxicity, such as the dissolution of specific metal nanoparticles into more bioavailable ionic forms, which may be more harmful to plants and soil biota (Auffan et al., 2009; Yang et al., 2014).

The transformation of nanoparticles in soil also includes processes such as aggregation and adsorption to soil particles or organic matter, which can influence their mobility and persistence. Smaller nanoparticles aggregate more readily, forming smaller particles that are less mobile and more likely to be retained in the upper soil layers (Lecoanet et al., 2004). This aggregation can reduce the risk of nanoparticles leaching into groundwater but may increase their potential for interaction with plant roots and soil microorganisms. Organic matter, such as humic substances and root exudates, can also coat nanoparticles, affecting their stability and uptake by plants. These interactions are not only influenced by the physicochemical properties of nanoparticles but also by the microbial activity in the soil. Soil microbes can facilitate the transformation of nanoparticles by producing extracellular enzymes and metabolites that alter the surface characteristics of nanoparticles or induce their dissolution (Maurer-Jones et al., 2013). Additionally, the presence of soil microorganisms can mediate the bioavailability of nanoparticles through the formation of biofilms, which can either enhance or limit nanoparticle uptake by plants depending on the microbial composition and the nature of the nanoparticle surface. The aging and transformation of nanoparticles in soil have significant implications for their environmental impact, particularly in the context of agricultural sustainability. For example, over time, some nanoparticles may lose their toxic properties, reducing their potential to harm plant health and soil ecosystems. However, the persistence of transformed nanoparticles in the soil matrix, especially in the case of highly stable metal oxides or insoluble sulfides, may pose long-term ecological risks, particularly if they are taken up by plants or consumed by soil organisms. Therefore, understanding the dynamics of nanoparticle aging and transformation in soil is essential for assessing the risks and benefits of using nanoparticles in agriculture.

The use of engineered nanoparticles (ENPs) in agricultural systems has garnered significant attention due to their potential to improve crop productivity, soil fertility, and pest control. However, the increasing application of nanoparticles in agriculture has raised concerns regarding their environmental fate, mobility, toxicity, and overall impact on agricultural ecosystems. Despite significant progress in understanding the role of particle size, surface coatings, and aging processes in nanoparticle behavior, several critical knowledge gaps remain that must be addressed to better predict and manage the risks associated with their use. These knowledge gaps pertain to both the fundamental scientific understanding of nanoparticle transformations in soil and the practical implications of their environmental and ecological effects.

One of the most pressing knowledge gaps is the need for a more comprehensive understanding of the long-term fate and behavior of nanoparticles in soils under field conditions. While laboratory-based studies provide valuable insights into the initial interactions between nanoparticles and soil components, they often fail to account for the complexity of real-world agricultural environments. Soil composition, texture, moisture content, pH, and microbial activity all influence the transport, transformation, and bioavailability of nanoparticles, yet the interactions between these factors are often poorly understood. For example, although smaller nanoparticles are typically more mobile and bioavailable, they may undergo aggregation or transformation over time, potentially reducing their toxicity but complicating their long-term effects. The influence of aging and surface transformations (e.g., oxidation, sulfidation, or adsorption to organic matter) on nanoparticle toxicity and transport remains poorly characterized, and further research is needed to determine how these processes alter the bioavailability of nanoparticles to plants and soil organisms (Keller et al., 2013). Surface coating is a crucial determinant of nanoparticle behavior and toxicity, yet the role of different coatings in modulating nanoparticle fate is still not fully understood. While some surface coatings (such as polyethylene glycol or polyvinyl alcohol) can enhance nanoparticle stability and reduce toxicity by preventing aggregation or shielding reactive surfaces, others may promote nanoparticle uptake by plants or microorganisms, thereby increasing their bioavailability and potential toxicity (Simonin and Richaume, 2015). Furthermore, coatings made from natural materials, such as humic substances, may interact with soil colloids or microbial biofilms, influencing both nanoparticle transport and toxicity in ways that are not yet fully elucidated. There is also a need to explore the effects of surface coatings on the long-term persistence of nanoparticles in soils, as well as their degradation and release of potentially toxic ions. Future research should aim to develop a better understanding of the interactions between coatings, nanoparticles, and the soil matrix, as well as how these interactions change over time as nanoparticles age and transform in the soil environment.

Another major knowledge gap lies in understanding the effects of nanoparticle aging on their toxicity and transport in agricultural ecosystems. While much is known about the immediate interactions between nanoparticles and plant or microbial systems, the long-term impacts of aging processes on nanoparticle toxicity remain largely unexplored. Aging processes such as aggregation, oxidation, and dissolution can alter the physical and chemical properties of nanoparticles, potentially reducing or increasing their toxicity depending on the transformation processes involved. For example, the aging of silver nanoparticles (AgNPs) in soil may lead to the formation of silver sulfide (Ag₂S), which is less toxic to plants and soil microorganisms compared to the uncoated AgNPs (Abbas et al., 2020). Conversely, the dissolution of nanoparticles such as zinc oxide (ZnO) or copper oxide (CuO) can release metal ions into the soil, increasing the toxicity of these nanoparticles over time (Parada et al., 2019). Understanding how nanoparticles transform and age in soils, and how these transformations impact their ecological effects, will be crucial for evaluating the long-term risks and benefits of nanoparticle use in agriculture.

The integration of nanoscale materials into agricultural systems also calls for better models to predict the transport and fate of nanoparticles in the environment. Current models of nanoparticle behavior in soil often fail to fully integrate the complexity of nanoparticle interactions with soil matrices and biological systems, making it difficult to predict the potential ecological consequences of nanoparticle exposure. The development of more accurate models that incorporate the effects of particle size, surface coating, aging, and environmental conditions will be essential for risk assessment and management of ENPs in agriculture. These models should account for the dynamic and heterogeneous nature of soils and agricultural environments, as well as the interactions between nanoparticles and the biota that inhabit these ecosystems. Moreover, field-based studies that examine the real-world transport and fate of nanoparticles under diverse soil and climate conditions are necessary to validate the assumptions made in laboratory-based models and ensure their applicability in agricultural practice. In addition to scientific advancements, future research should focus on developing strategies for minimizing the potential risks associated with the use of nanoparticles in agriculture. One promising avenue is the development of “green” nanoparticles, which are synthesized using sustainable methods and incorporate biodegradable or non-toxic materials that reduce the risk of long-term environmental contamination. For example, the use of biopolymers, natural surfactants, or plant-derived materials such as nanoparticle coatings could offer an environmentally friendly alternative to traditional synthetic coatings (Mondéjar-López et al., 2024). Furthermore, precision agriculture techniques, such as targeted delivery systems for nanoparticles, could help reduce the environmental impact of nanoparticle applications by ensuring that they are delivered only to the areas of the soil or plant where they are needed most, thereby minimizing the risk of unintended exposure to non-target organisms.

In conclusion, while significant progress has been made in understanding the toxicity, transport, and transformation of nanoparticles in agricultural ecosystems, substantial knowledge gaps remain that must be addressed in future research. To effectively manage the risks and maximize the benefits of nanotechnology in agriculture, we must deepen our understanding of how particle size, surface coatings, and aging processes influence nanoparticle behavior in soils and their impact on plant and microbial health. Interdisciplinary research that combines material science, environmental science, and agricultural practices will be critical for addressing these challenges and ensuring the sustainable use of nanoparticles in agriculture.

Multiple factors, including particle size, surface coating, and aging processes, influence nanoparticles’ toxicity and transport in agricultural ecosystems. As nanotechnology continues to expand its role in agriculture, understanding the interactions between engineered nanoparticles (ENPs) and the environment become increasingly critical for ensuring their safe and practical application. Nanoparticle size determines their mobility, bioavailability, and potential toxicity. Smaller nanoparticles are typically more mobile and can penetrate plant tissues more readily, increasing their potential for toxicity. However, surface coatings can modify these properties, enhance the stability of nanoparticles, reduce toxicity, and improve their interaction with soil and plants. Coatings such as organic polymers or natural compounds can prevent aggregation and improve nanoparticle dispersion, thereby influencing their transport and uptake by plants. At the same time, these coatings can alter the environmental fate of nanoparticles, either mitigating or exacerbating their toxic effects depending on the materials used and the environmental conditions. The aging of nanoparticles in soil introduces additional complexities in their behavior and environmental impact. Over time, nanoparticles such as aggregation, oxidation, or dissolution may transform, which can alter their toxicity and mobility. For example, metal-based nanoparticles may oxidize or form fewer toxic compounds over time, reducing their potential to harm plants and soil organisms. However, in some cases, aging processes may release more bioavailable and toxic ions, complicating risk assessment. Despite considerable advancements in understanding the behavior of nanoparticles under laboratory conditions, significant knowledge gaps remain regarding their long-term effects in real-world agricultural systems. Future research should address these gaps by exploring the interactions between nanoparticles and various soil components, plant systems, and microorganisms under diverse environmental conditions. Furthermore, while the potential benefits of nanoparticles in agriculture, such as enhanced nutrient delivery and pest control, are promising, their widespread use necessitates careful consideration of their environmental and ecological risks. A more comprehensive understanding of nanoparticle transformations in soil and the development of more accurate models of nanoparticle transport and fate will be essential for informed decision-making in agricultural nanotechnology. Moreover, using environmentally benign materials for surface coatings and adopting precision farming techniques could help mitigate potential risks while optimizing the benefits of nanoparticles in farm practices. Thus, balancing the promise of nanotechnology with environmental stewardship will require ongoing research, interdisciplinary collaboration, and a commitment to sustainable agricultural practices.

Understanding nanoparticles’ dissolution, toxicity, and transport in agricultural ecosystems has significant implications for environmental sustainability, food safety, and agricultural productivity. Variations in particle size, surface coatings, and aging processes can dramatically influence nanoparticle behavior, affecting their mobility through soil, plant uptake, and potential accumulation in food crops. Smaller particles, for example, may dissolve more readily and move farther through the soil, increasing exposure potential and bioavailability. Surface modifications can alter reactivity and toxicity, impacting soil microbiota and plant health. Furthermore, aging in natural environments may change the particles’ physicochemical properties, influencing long-term environmental fate. These factors underscore the need for precise risk assessments and the development of safer nanomaterials tailored for agricultural use, ensuring that the benefits of nanotechnology do not come at the expense of ecological and human health.