What happens to microplastics and nanomaterials in crop–soil systems?

Plastic mulch films, sewage sludge, irrigation water and nano-enabled agrochemicals all bring tiny particles into farm soils. Where those particles go, whether crops take them up and what they do to soil life are still largely open questions.

Question

What is the fate of novel pollutants such as nanomaterials and microplastics in the crop–soil–microbial system? This covers their sources and amounts in farm soils, their transformation and movement, their uptake by roots and transfer to edible parts, their effects on soil organisms and functions, and the resulting risks to food safety.

Background

The question is in the theme "sustaining healthy agroecosystems" of the 100 essential questions for the future of agriculture, compiled from 419 questions submitted worldwide in 2022. The authors note that while heavy-metal pollution is a long-standing concern, nanomaterials, microplastics, antibiotics and their resistance genes have gained attention more recently [1].

What is known

Microplastics (particles under 5 mm, including nanoplastics under 0.1 µm) have been described as a possible global-change threat to terrestrial ecosystems, with growing evidence that they interact with soil invertebrates, fungi and pollinators [2].
In 324 samples from 108 carrot and potato fields across the United Kingdom, soils held 1,320–8,190 microplastic particles per kg; fields with plastic crop covers in the previous 10 years averaged about 4,690 particles per kg, against about 2,670 where none were used [3].
In wheat and lettuce, submicrometre and micrometre particles of polystyrene and polymethylmethacrylate entered roots through cracks at sites of lateral root emergence and moved to the shoots, driven by transpiration [4].
For engineered nanomaterials, the lack of data on environmental concentrations is a key gap; a consensus is emerging that they are less toxic than equivalent dissolved materials but more toxic than bulk ones, and may pose a relatively low environmental risk, though definitive conclusions cannot yet be drawn [5].

What would count as progress

No single result settles a question like this; contributions like these would move it forward:

Standardised, interlaboratory-validated methods for counting and identifying micro- and nanoplastics in soil and plant tissue, so that studies become comparable.
Field studies at realistic concentrations that measure uptake into edible parts and effects on soil functions over several seasons.
Mass-balance models of plastic and nanomaterial inputs and losses for farm soils, checked against monitoring data.

References

Hu, Y. et al. (2023). 100 essential questions for the future of agriculture. Modern Agriculture 1(1), 4–12.
de Souza Machado, A. A. et al. (2018). Microplastics as an emerging threat to terrestrial ecosystems. Global Change Biology 24(4), 1405–1416.
Cusworth, S. J. et al. (2024). A nationwide assessment of microplastic abundance in agricultural soils: the influence of plastic crop covers within the United Kingdom. Plants, People, Planet 6(2), 304–314.
Li, L. et al. (2020). Effective uptake of submicrometre plastics by crop plants via a crack-entry mode. Nature Sustainability 3(11), 929–937.
Lead, J. R. et al. (2018). Nanomaterials in the environment: behavior, fate, bioavailability, and effects—an updated review. Environmental Toxicology and Chemistry 37(8), 2029–2063.

Source

Imported from 100 essential questions for the future of agriculture, question 61, curated by Hu et al. Listed as open in the source (2023) and still an active research question as of 2026-10-20. The statement above is written in our own words; see the source for the original wording, history and discussion.