Microplastics in agricultural soils: sources, soil–plant interactions, ecotoxicological effects and food security concerns

1 Introduction

Over the last century, the swift growth of plastic production has radically changed material cycles worldwide, with total production reaching record-high levels in recent decades. In 2020, the global production of plastics surpassed 367 million metric tons, adding to an estimated amount of more than 8000 million metric tons of plastic waste since 1950 (1–3). Of this waste, only a small portion is properly disposed of, with approximately 4900 million metric tons remaining in landfills and natural settings, which demonstrates the extensive environmental impact of plastic materials (1). This has led to the proliferation of plastics throughout all ecosystems and is now becoming linked to the Anthropocene as a defining characteristic (4).

In recent years, there has been growing awareness of microplastic contamination in the environment, and agricultural soils have been identified as a significant reservoir for plastic waste due to intensive agriculture, wastewater use, biosolid application, and atmospheric deposition. Recent evidence also indicates that the terrestrial ecosystems may be more contaminated by microplastics than aquatic ecosystems, underscoring the need to comprehend the fate and ecological impacts of microplastics in terrestrial environments (5–8).

The environmental impact of plastic pollution is exacerbated when plastics are broken down into smaller particles. Larger plastic materials gradually break down into microplastics and smaller particles through physical, chemical, and biological degradation mechanisms (ultraviolet radiation, mechanical abrasion, thermal degradation, hydrolysis, and microbial activity) (9–11). They produce particles that are usually less than 5 mm in diameter (microplastics) and have greater mobility, bioavailability, and interaction capacity in the ecosystem (12, 13). Microplastics can endure in soil, water, and the atmosphere because of their small size and large surface area, which promote their extensive distribution throughout the environment (14, 15). Their capability to communicate with soil particles, microorganisms, and plant systems makes them even more ecologically relevant, as demonstrated in Figure 1.

The massive consumption of plastic products in agriculture, industry, and home life has also contributed to the increase in the proportion of microplastics in territorial habitats. In the agricultural sector, plastics have a variety of applications, such as mulching films, irrigation systems, greenhouse covers, and fertilizer covers, whereas in the industrial and household sectors, plastics are used as packaging, building materials, textiles, and consumer products (17, 18). These extensive uses have resulted in the active disposal of plastic waste into the environment, ultimately causing microplastic pollution in soil.

Microplastic pollution has become a critical environmental concern because it is difficult to remove, widely dispersed, and can significantly impact processes and human health within ecosystems (7). Microplastics may modify important physicochemical characteristics, such as bulk density, porosity, aggregate stability, and water retention, in agricultural soils, affecting nutrient availability and soil functionality. These changes can directly affect soil fertility and crop production; hence, there is a need to understand their dynamics in an agroecological system.

1.1 Existing reviews and their limitations

Some reviews have been written about various issues related to microplastic contamination in terrestrial ecosystems, such as occurrence, environmental fate, analytical methods, uptake by plants, ecotoxicological effects, and impacts on human health (5, 7, 13, 16, 19, 20). The majority of these reviews focus on a particular theme, such as analytical detection, soil physicochemical changes, plant toxicity, and/or environmental risk assessment. While these studies have provided significant insights into the sources, soil–plant–microbe interactions, ecotoxicological effects, productivity, and food security implications of microplastic pollution, there is a limited synthesis that integrates them.

1.2 Novelty and objectives of the review

Although previous reviews have examined specific aspects of microplastic contamination in terrestrial and agricultural systems, this review provides an integrated soil–microplastic–microbe–plant perspective with agricultural sustainability and food security. It links microplastic sources and environmental pathways, changes in soil properties, microbial communities, nutrient cycling, plant uptake and translocation, crop productivity, co-contaminant interactions, and food-chain transfer.

The review further adopts a systems-level perspective by examining how soil and rhizosphere processes influence microplastic retention, mobility and plant uptake, while identifying key methodological limitations and knowledge gaps, including the predominance of laboratory studies, variability in analytical methods, limited long-term field evidence, and insufficient understanding of environmentally realistic exposure conditions. This integrated approach provides a basis for improved risk assessment, monitoring, mitigation and sustainable management of microplastic contamination in agricultural soils.

This review paper has the following objectives:

• To comprehensively summarize the important sources, environmental pathways, accumulation and fate of microplastics in agricultural soils.
• To assess the effects of microplastics on soil physicochemical properties, soil microbial communities, soil nutrient cycles and soil health.
• To summarize what is known about the uptake, movement and physiological responses of the crop plants to microplastics and their significance for agricultural yields.
• To evaluate the ecological, food safety and human health risk of the soil–plant–food pathway transfer of microplastics.
• To establish the major gaps in knowledge, methodological constraints, and future research needs to enhance monitoring, risk assessment and sustainable mitigation measures to combat microplastic pollution in agricultural ecosystems.

2 Methodology

2.1 Literature search and review approach

To prepare this narrative review, a comprehensive literature search was performed to synthesize current knowledge on the occurrence, sources, environmental fate, soil–plant interactions, ecotoxicological effects, and food-security implications of microplastics in agricultural soils. The literature search was designed to provide broad and thematically relevant coverage of the available evidence. The most relevant peer-reviewed articles were retrieved from leading scientific databases, such as ScienceDirect, PubMed, and Google Scholar.

The literature search covered studies published between 2015 and 2026, a period selected because research on microplastics in agricultural soils has expanded rapidly during the past decade. Earlier landmark studies published before 2015 were also included where necessary to provide historical context and establish fundamental concepts. Relevant studies were identified using a combination of the following keywords: microplastics in agricultural soil, soil microplastic plant interactions, microplastic contamination in soil, soil health, and crop productivity. Additional combinations of these terms were used where necessary to identify literature addressing specific aspects of the review, including sources and pathways of microplastic contamination, soil physicochemical properties, microbial responses, plant uptake and translocation, crop responses, ecotoxicological effects, and food-security implications.

Research papers were chosen based on their attention to terrestrial and agricultural ecosystems, especially those covering the sources, behavior, transport modes, and effects of microplastics on soil quality and crop yields. Because this was a narrative review, study selection was based on relevance to the article’s objectives and thematic scope rather than on a formal risk-of-bias assessment or evidence synthesis. The selected literature was organized into thematic sections covering (i) sources and pathways of microplastics in agricultural soils, (ii) environmental fate and transport, (iii) effects on soil physicochemical and biological properties, (iv) soil–microplastic–microbe interactions, (v) plant uptake and translocation, (vi) crop growth and productivity, and (vii) ecotoxicological, food-safety, and food-security implications. Findings were subsequently synthesized narratively, with emphasis on areas of agreement, variability among experimental conditions, methodological weakness, and identified knowledge gaps.

2.2 Study selection and screening process

The selection process involved identifying potentially relevant literature, removal of duplicate records, screening of titles and abstracts, and subsequent assessment of full-text articles. Publications were retained when their primary focus or relevant findings concerned microplastics in agricultural or terrestrial soils and when they contributed evidence relating to at least one of the thematic objectives of the review. Where a number of publications addressed closely related findings, preference was given to peer-reviewed primary research studies, recent evidence, and studies that provide direct information relevant to agricultural soil systems.

The screening process was conducted by reviewing the relevance of the identified articles against the predefined scope and eligibility criteria. Those articles that did not provide information relevant to agricultural or terrestrial soil systems were excluded. The final body of literature was then reviewed and categorized based on the major themes addressed in the review.

2.3 Inclusion and exclusion criteria

Inclusion criteria

• Peer-reviewed journal articles
• English-language publications
• Studies investigating agricultural or terrestrial soils
• Experimental and field studies
• Studies reporting sources, occurrence, transport, soil properties, plant uptake, microbial interactions, crop responses or food security implications

Exclusion criteria

• Conference abstracts
• Editorials
• Opinion papers
• Studies restricted to marine ecosystems

3 Microplastics

Microplastics are minute pieces of plastic, usually less than 5 mm in diameter, and are one of the most enduring and ubiquitous types of environmental pollution. These particles are made of synthetic polymers that develop from fossil/bio-based feedstock and find extensive application in industrial, agricultural, and household applications.

Microplastics can be grouped into primary and secondary microplastics based on their source (Figure 2). Primary microplastics are manufactured with specific intent by creating microscopic products to be used in other products, including personal care products, industrial abrasives, and cleaning agents. These particles are generally polyethylene (PE), polypropylene (PP), and polystyrene (PS) polymers (15, 21).

Conversely, secondary microplastics refer to the fragmented material of larger plastic due to exposure to the environment (weathering), such as ultraviolet light, mechanical erosion, oxidation, and microbial degradation (22, 23). These processes produce microplastics in several forms, such as plastic packaging, textiles, tires, and agricultural films.

Microplastics have varying physical properties, including size, shape, and structure. The typical types are fibers, fragments, foam, film, pellets, and filaments (24, 25). These differences affect environmental actions such as transportation, retention, and interaction with soil components.

Microplastics are reported to be found more frequently in soil on land, especially in agricultural soils, where they are currently considered emergent pollutants that have important effects on soil quality, plant life, and environmental sustainability (26–30).

3.1 Sources and pathways of microplastic accumulation in agricultural soils

The accumulation of microplastics in agricultural soils can occur through a variety of interactions, the main ones being agricultural activities, waste disposal mechanisms, and transport in the environment.

Another cause of significant micro plastics in agricultural systems is the large use of plastic constructed materials such as mulching films, greenhouse covers, irrigation pipes, and packaging material. These substances are fragmented by environmental factors such as ultraviolet radiation, temperature changes, and mechanical interference, leading to in situ microplastic production in soil systems (31–35).

Another pathway of microplastic entry is through organic amendments such as compost, biosolids, and sewage sludge. They also have plastic residues in these materials, which are the result of household waste, personal care products, and runoff in urban areas. During composting and sludge treatment, plastic materials partially decompose, resulting in the emergence of microplastics that remain in the end products (30, 36–38). The amount of microplastics in sludge-amended soils has been reported to be more than 10⁵ particles kg, which is an extraordinary example of this contamination route (39).

Wastewater irrigation is another source of microplastic contamination, especially in areas where treated or untreated wastewater is used on farms. These water bodies contain microplastics, which are a result of domestic, industrial, and textile activities that contribute to their slow build-up in soil systems (40, 41).

Another unobtrusive yet significant source of microplastics is atmospheric deposition, where airborne substances are generated from urban emissions, road dust, and synthetic fibers that are carried and deposited in the fields (27).

In addition to external inputs, the process of soil interaction with microplastics affects soil processes through interactions with contaminants and microbial communities. Their capacity to adsorb organic pollutants, such as pesticides and polycyclic aromatic hydrocarbons, has the potential to modify contaminant mobility and bioavailability in soil systems (42). Moreover, microplastics offer a habitat for colonization by microbes, facilitating biofilm formation and changing the dynamics of microbial communities (43).

Overall, the presence of microplastics in agricultural soil is influenced by the complex of direct inputs, routes of environmental transport, and soil factors (Table 1). These processes collectively affect the maintenance, distribution, and ecological effects of agroecosystems, as shown in Figure 3.

Table 1. Sources, entry pathways, contributing factors, and soil interactions of microplastics in agricultural soils.

3.2 Microplastics impact on soil quality

Microplastic pollution has become a major factor influencing soil functionality because it affects the structural, chemical, and biological stability of agricultural soils. These effects are multifaceted and context-specific, depending on microplastic properties, including size, shape, and polymer type, soil properties, and environmental conditions (44). Figure 4 shows that microplastics interfere with various elements of the soil system, which eventually affects nutrient cycles, microbial activities, and soil fertility.

One of the most immediate effects of microplastic contamination is the variation in the physical structure of the soil. The introduction of low-density plastic particles into soil matrices may slow down the bulk density and impact the stability of aggregates, which, in turn, may influence pore connectivity and water movement (31, 45, 46). Similarly, an equivalent loss of soil stability, of the order of 25%, can occur as a result of fracture point penetration in soil aggregates, compromising structural cohesion and the penetration of roots and roots in soil.

In addition to affecting soil structure, microplastics affect the chemical processes of soil, particularly nutrient dynamics. Research has found that soil pH and the availability of nutrients and nitrogen can be changed by microplastics, which can be ammonium (NH₄⁺) and nitrate (NO₃^-), depending on the stage of crop growth and the type of polymer (47). This is because of their large surface area, which allows them to adsorb nutrients and contaminants that can potentially alter their surface mobility and bioavailability in soil systems (48). Moreover, the excretion of additives and degradation products of plastics also introduces other chemical stressors that would disrupt the cycling of soil nutrients.

Microplastic pollution is especially sensitive to soil biological processes. Microplastics can decrease microbial diversity, prevent enzymes, and interfere with microbial interactions within the soil matrix (47, 49). As an illustration, the activities of enzymes like urease (14%), β-glucosidase (31%), and dehydrogenase (41%) have been found to be reduced after being exposure to microplastics (9, 50). These enzymes are important in nutrient cycling, and their inhibition may have important effects on soil productivity and fertility.

Furthermore, microplastics may compromise the movement of microorganisms and access to food, disrupting ecological interactions within the soil (51). These disturbances can have reverberating impacts on vegetation-microorganism interactions, the tapestry of decomposing organic material, and long-term soil well-being. In general, microplastics have complex impacts on soil systems, as they can simultaneously affect the physical structure, chemical makeup, and biological activity of the soil (Table 2). These effects underscore their capacity to degrade agricultural soil, balance nutrient cycling, and eventually decrease agricultural yields.

Table 2. Microplastics impact on soil physical, chemical, and biological characteristics.

While microplastics consistently affect the physical, chemical, and biological properties of soil, these effects are influenced by the type of polymer, particle size, concentration in soil, soil properties, and the duration of exposure. The majority of the evidence is from laboratory experiments conducted at relatively high contamination levels; this may not necessarily apply to field conditions. Long-term field studies with environmentally realistic microplastic concentrations and standardized methods are required to make a precise assessment of the cumulative effects of microplastics on soil quality and ecosystem functioning.

4 Soil–microplastic–microbe interactions

Microplastic pollution adds a layer of interaction in soil ecosystems by engaging microbial communities and altering their functional activities in nutrient cycling. Microbial communities are the most important contributors to soil fertility and are sensitive to environmental disruption. The incorporation of microplastics can profoundly affect the community, including its structure, diversity, and functionality.

Microplastics can serve as physical disruptors and ecological niches in soil systems, as shown in Figure 5. They can enhance microbial stress, decrease biodiversity, and change community composition, causing unbalanced biochemical processes in the soil (47, 49, 69).

In addition to these direct biological impacts, microplastics carry environmental pollutants. Their hydrophobic surfaces cause them to easily adsorb pesticides, polycyclic aromatic hydrocarbons (PAHs), and pharmaceutical compounds. Environmental factors influencing the adsorption and subsequent release of these compounds include pH, temperature, salinity, and organic matter content (61). This process can form localized areas of chemical stress that have an additional impact on microbial activity and metabolic processes.

Microplastic pollution also affects soil fauna, which play vital roles in decomposition systems and elemental cycles. Disturbance of soil fauna can decrease the rate of organic matter degradation, change nutrient levels, and detrimentally affect helpful symbiotic relationships, such as mycorrhizal interactions (6, 70).

These interactions prove that microplastics are not only pollutants but also active regulators of microbial ecology in soil, and their effects on soil health and agricultural sustainability are important.

Existing data suggest that microplastics affect soil microbial communities and enzyme activities, but the extent of the impact varies with polymer type, soil characteristics, exposure conditions, and microbial adaptation. The varied results found among studies reflect the complexity of soil–microbe interactions. Future studies will benefit from incorporating long-term field experiments with metagenomic and metabolomic approaches to understand the mechanisms underlying microbial responses and ecosystem function.

4.1 Uptake and translocation of microplastics in plants

The concentration of microplastics in farm soils has become a growing concern due to their potential entry into plant systems and, consequently, the food chain. The absorption and internalization of microplastics in plants are governed by various factors, including particle size, surface charge, plant type, and root structure.

The main point of entry of microplastics is the root system, due to which microplastic particles enter the rhizosphere and then through physical barriers. Smaller particles, especially those on the verge of the nanoscale, can traverse intercellular spaces via apoplastic pathways, allowing transport along the cell wall continuum without traversing cell membranes (45). Conversely, coarse particles tend to remain on the root surface and in the pore space, limiting their interiorization.

In addition to the apoplastic process, other pathways have been suggested, including symplastic movement and the crack-entry mechanism. Symplastic transport entails cell-membrane exchange of particles into the cytoplasm, which may be linked to endocytosis-equivalent mechanisms and to intercellular exchange via plasmodesmata (42). It has also been observed that some crack-entry pathways, especially where there is lateral root emergence or epidermal discontinuities, have likely served as potential entry points into plant roots of microplastics (71).

After absorption, microplastics can accumulate in specific areas of the root, such as the root cap, subapical meristem, and differentiation areas. Particles can be carried by vascular tissues (especially by the xylem) to aerial plant areas, such as stems, leaves, and growing tissues in these regions (72, 73). Their adhesion to plant surfaces, such as being linked to epicuticular wax, can contribute to their retention in plant tissues (50).

Microplastic deposition has been detected in a large number of crop species, such as lettuce, rice, maize, cucumber, onion, and even model plants, such as Arabidopsis thaliana (74, 75). These data demonstrate the ubiquity of microplastics in vegetative systems and raise concerns over their possible movement along the food chain and the implications of such food contamination and health hazards in humans.

There are indications that microplastics are taken up and translocated in plants, but the mechanisms underlying these processes remain unclear in the field. The majority of studies are conducted in controlled laboratory systems, thereby reducing their environmental relevance. Sensitized detection methods and long-term field investigations are required to understand plant uptake, transfer to food chains and related human health risks better.

4.2 Crop growth and yield effects

Microplastic contamination of soil has a direct or indirect impact on plant growth, physiology, and productivity (Table 3). These effects are due to interactions at various levels, such as root systems, soil properties, and relationships between plants and microbes.

Table 3. Impact of microplastics on crop growth, physiology, and harvest.

Polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyacrylonitrile (PAN), High-density polyethylene (HDPE), polylactic acid (PLA), polyethylene 2,5-furan-dicarboxylate (PEF), polyester microfibers (PMFs).

Physical interference at the root level is mostly linked to the direct effects of microplastics on plant growth. Microplastics can block root pores, slow root growth, and disrupt nutrient and water absorption (45, 88, 91). Smaller nanoparticles, being more mobile, can enter root tissues and interfere with inner physiological processes (30, 42).

Indirect impacts are mediated by changes in soil properties and microbial activity. Alterations in soil structure, nutrient content, and microbial community structure may dramatically affect plant growth conditions. As microorganisms are important in the cycles of nutrients and the well-being of plants, alterations in microbial activity may further exacerbate the adverse effects of microplastic influence on crop systems (7).

Surveys on microplastics have also revealed that they can impact major physiological and biochemical mechanisms in plants. These include a decrease in chlorophyll content, suppression of photosynthetic activity, and evocation of oxidative stress responses. Quantitative data have shown a decrease in the plant biomass (approximately 13%) and chlorophyll content (approximately 28%), which revealed the significant effects on plant productivity (42). Moreover, microplastics may induce antioxidant defense responses, indicating oxidative stress and metabolic disturbance in plant tissues (87, 92).

There are also changes in the parameters of structural growth, where a decrease in stem length, root biomass, and above-ground biomass is observed under high levels of microplastics (91, 93). These structural changes are a direct result of low crop yield and agricultural productivity.

Moreover, microplastics affect the biochemical processes in soils that control nutrients. As an illustration, urease activity (5-12.2%) decreases can be identified that can influence nitrogen recycling and the nutrient supply to plants (9). As nitrogen is an essential nutrient for plants, these disturbances can have drastic ramifications on crop performance.

Overall, the impact of microplastics on crop systems is complex and includes interactions with soil characteristics, microbial communities, and plant physiology. The combination of these effects is highly challenging for sustainable agriculture, and it is necessary to conduct additional studies under field conditions (Table 4).

Table 4. Integrated summary of the impacts of microplastics on physical, biological and ecotoxicological dimensions of agricultural soils.

While many studies have documented the negative effects of microplastics on plant growth and chlorophyll content, biomass, and yield, the plant responses are variable and highly dependent upon polymer type, size, concentration, duration of exposure, soil properties, and crop species. For instance, PET and PAN microplastics were found to improve rice grain production by 22.2-30.8% (9), suggesting that under certain exposure conditions the effects of microplastic exposure on crop performance may be positive. These responses have been attributed to changes in soil physical characteristics such as increased porosity and aeration, changes in nitrogen availability, and crop-specific physiological responses. The positive effects were, however, seen under specific experimental conditions and should not be regarded as a general beneficial effect of microplastics on crop productivity. Higher concentrations, extended exposure or other types of polymers often lead to reduced biomass, decreased photosynthesis, oxidative stress, and decreased yields. The majority of the evidence comes from short term laboratory research, which reduces the field applicability. There is a need for long-term, multi-disciplinary field investigations to set realistic limits of contamination to effectively evaluate the risk to agriculture.

5 Food security and sustainability implications

The issue of microplastic pollution in agricultural systems is a rising problem of food security and environmental sustainability worldwide. Their ubiquitous presence in soil, water, and crop systems is evidence of the off-target effects of the intensive use of plastics in modern agriculture. Simultaneously, with enhanced crop productivity and resource efficiency, plastic-based technologies, including mulching films and irrigation systems, have raised new environmental hazards due to their long-term persistence in the soil has raised new environmental hazards (30, 94).

One such issue related to microplastics is that they might find their way into the food chain by plant absorption and contamination of crops on the surface. There is also evidence of the existence of microplastics in edible tissues of plants, such as cereals and vegetables, which points to a direct exposure route in humans (88, 95). Moreover, they can adsorb and carry co-contaminants, such as heavy metals and organic contaminants, which also increase potential health risks (16). Recent research that claims the presence of microplastics in the human body highlights the importance of working towards both environmental and human health approaches to this problem (96).

In addition to food safety issues, microplastics can threaten sustainable agricultural practices in the long run by shifting soil fertility, disrupting nutrient cycling, and undermining the interactions between plants and microbes. These consequences make agroecosystems less resilient, especially in intensive farming and frequent plastic application. Thus, it is crucial to control microplastic contamination to ensure the sustainability of agricultural systems and safeguard crop productivity. Figure 6 depicted the integrated conceptual framework for the environmental fate of microplastics in agricultural soils and their impacts on food security.

5.1 Risk assessment and food security concerns

The dangers of microplastic contamination of agricultural soils are directly connected to their persistence, mobility, and interactions with other environmental contaminants. Microplastics may also serve as vectors for heavy metals, pesticides, and organic pollutants, promoting their transportation and enhancing their bioavailability in the soil-plant system (16).

The discovery of microplastics in edible crops such as lettuce, rice, wheat, and maize is a major concern for food and human safety (30, 71). Bioaccumulation and biomagnification may occur through transfer between trophic levels, causing harm to wildlife and human health (7, 97, 98).

Given these risks, it is time to establish standardized assessment frameworks to determine the extent of microplastic contamination in agricultural systems, particularly concerning food safety thresholds and the risk of long-term exposure.

5.2 Integrated conceptual framework for microplastic impacts on agricultural sustainability

It is important to view the microplastic contamination of agricultural systems as a multi-faceted environmental process rather than a one-dimensional pollutant problem, since it can have a range of negative impacts on soil quality, microbial ecology, plant physiology, crop productivity and food security. The microplastics from agricultural plastic mulches, plastic covers of greenhouses, irrigation systems, wastewater irrigation, sewage sludge, compost application, atmospheric deposition and degradation of larger plastic debris continuously accumulate in the agricultural soils, as shown in Figure 7. The fate of their environment depends on the size, shape, type and surface chemistry of the particles and soil properties like texture, pH, organic matter content and moisture content (99).

After accumulation, microplastic create changes in the soil’s physical, chemical, and biological structure, which include the stability of soil aggregates, bulk density, porosity, water holding capacity, nutrient availability, microbial diversity, and enzyme activities. These alterations lead to breakthroughs in nutrient cycles and advantageous plant–microbe relations, weakening soil quality and ecosystem services. At the same time, microplastics serve as vectors for co-contaminants such as heavy metals, pesticides and persistent organic pollutants, thus exacerbating ecological risks. These combined effects of degraded soil health and ingestion of smaller microplastic particles by plant roots cause oxidative stress, decrease photosynthetic efficiency, inhibit growth and yield, and lower crop production. They are also translocated to edible parts of plants and thus pose additional concerns about food-chain contamination and human health effects.

The proposed framework also considers dynamic feedback mechanisms in which deterioration of soil structure increases microplastic retention, while a change in the microbial community affects the transformation of contaminants, and changes in rhizosphere processes affect the mobility and uptake of microplastics by plants. This systems-level approach will include the various interconnected pathways between microplastic contamination and agricultural sustainability, and will form a scientific basis for future risk assessment, mitigation and sustainable soil management.

5.3 Knowledge gaps and future directions

Although more studies have been conducted on microplastics, major gaps in knowledge concerning their behavior and effects within agricultural systems remain. Existing knowledge is highly related to carefully managed laboratory experiments, and there is little field-based information to evaluate the long-term ecological and agronomic impacts.

The major research gaps based on their priority are:

• Priority I: Long-term field experiments linking MP accumulation with crop productivity.
• Priority II: Standardized extraction and quantification protocols.
• Priority III: Mechanistic understanding of rhizosphere-mediated transport.
• Priority IV: Lack of knowledge on the combined effects with pesticides and heavy metals.
• Priority V: Lack of knowledge on the threshold concentrations for food safety risk assessment.

Subsequent studies must be conducted to provide standardized methods, field tests on a long-term basis, and multidisciplinary studies will be necessary to learn the destiny and effects of microplastics in agroecosystems. Moreover, the design of alternative materials to regular plastics that are sustainable and better waste management is necessary to reduce the impact of microplastic pollution.

6 Conclusion

Microplastic contamination has been identified as a major challenge to agricultural soils, resulting in changes of physicochemical characteristics, microbial communities, nutrient cycles and plant growth and productivity. Additional pathways by which they are observed to accumulate in soils through agricultural activities, wastewater irrigation, organic amendments, and atmospheric deposition also heighten risks to food chain transfer, food security, and environmental sustainability.

A consistent pattern across the reviewed studies is that the effects of microplastics are governed by multiple interacting factors, including polymer composition, particle size and morphology, concentration, soil characteristics, crop species, and environmental conditions. While most studies have found negative impacts on soil health and plant growth, the results have been inconsistent due to the variety of experimental conditions used, underscoring the complexity of microplastic–soil–plant interactions. In addition, most of the research conducted has been in a laboratory setting and analytical techniques vary, making it difficult to compare results and to accurately predict ecological risks.

Long-term field studies, standardization of methods for microplastic detection and quantification, and mechanistic studies of interactions among soil, microbes, and plants under realistic agricultural conditions should be priorities for future research. Creating alternatives to traditional plastics that are sustainable, implementing better waste management practices, and science-based monitoring and regulatory measures will be key in reducing microplastic contamination. Their priorities will enhance our understanding of the behavior of microplastics in agroecosystems and help achieve sustainable production whilst ensuring soil health and food security.

Overall, the evidence suggests that microplastic pollution is not just a soil contaminant but a multi-scale stressor on agriculture, affecting soil structure, microbial ecology, plant physiology, and food safety. This review demonstrates that these interrelated processes must be understood within a unified framework and suggests that a systems-based risk assessment approach is needed to integrate the various environmental monitoring, soil health, crop response, and human exposure pathways. This multi-faceted approach serves as a basis for future mitigation measures and sustainable farming practices.

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Footnotes

Edited by: Francesco De Mastro, University of Bari Aldo Moro, Italy

Reviewed by: Aowlad Hossain, University of Rajshahi, Bangladesh

Sarra Hechmi, Water Research and Technology Center, Tunisia