Maintaining soil health is critical for water regulation, pollutant filtration, nutrient cycling, and long-term agricultural productivity.1 To support these functions, researchers are exploring novel materials that can enhance soil structure and performance.
Image Credit: William Edge/Shutterstock.com
Carbon nanotubes (CNTs) are one material that is gaining attention. They are hollow cylindrical nanostructures composed of rolled graphene sheets, with length-to-diameter ratios often exceeding 106.
CNTs are typically classified as single-walled (SWCNTs) or multi-walled (MWCNTs), and are already used in sectors such as electronics, energy storage, and biomedicine.2 More recently, they have been investigated for their potential in soil reinforcement, sustainable agriculture, and mitigating environmental stressors in soil ecosystems.
Enhancing Crop Growth Through Water and Nutrient Management
CNTs can significantly improve water transport and nutrient availability in plants. Water molecules confined within the narrow, one-dimensional channels of CNTs exhibit single-file diffusion and, under ideal conditions, ballistic transport.
When incorporated into plant systems, these nanotubes can integrate with vascular structures, particularly the xylem, where they align in head-to-tail configurations. This organization may facilitate faster and more efficient water distribution throughout the plant, promoting improved hydration and growth.
In addition to water transport, CNTs can enhance fertilizer retention due to their high surface tension and adsorption capacity. Studies have shown that CNTs can slow the degradation of fertilizers, improving micronutrient availability and uptake.
These combined effects support greater crop productivity by optimizing water use and prolonging the functional lifespan of applied nutrients.3
Case Study: CNTs and Crop Growth in Basella alba
A study published in Chemical and Biological Technologies in Agriculture investigated the effects of MWCNTs on the growth and development of Basella alba (Malabar spinach).⁴
Five plant pots were used: one control (C) and four experimental groups (S1–S4), treated with increasing concentrations of MWCNTs—50, 100, 150, and 200 µg/mL, respectively.
The results showed that plants in groups S3 and S4, treated with 150 and 200 µg/mL, exhibited the most robust growth under suboptimal conditions. Specifically:
- S3 recorded the highest root length (8.9 cm) and shoot length (48 cm).
- S4 showed the highest vigor index (4390.2), indicating overall plant health and resilience.
- Leaf count significantly increased in S3 and S4 compared to both the control and lower-concentration groups (S1 and S2).
Phenotypic analysis confirmed that higher MWCNT concentrations, within a specific range, enhanced plant height and leaf number, supporting the potential of CNTs in improving crop performance under stress conditions.4
Impact of MWCNTs on Soil Microbiota and Nutrient Cycling
MWCNTs have shown promise in improving soil health by supporting microbial ecosystems and enhancing nutrient cycling, particularly in soils contaminated with heavy metals.
Studies have demonstrated that CNTs can stimulate phytoremediation by promoting root development and biomass accumulation in plants growing in polluted environments.
In one study, researchers investigated the effects of MWCNTs on the rhizosphere microbial communities of Solanum nigrum L. (black nightshade) grown in cadmium- and arsenic-contaminated soils from Liuyang City, China.⁵
Soil samples were treated with MWCNTs, while a control group received no nanotube treatment. Results showed that MWCNT application altered microbial community composition, increasing the relative abundance of taxa known to promote plant growth, including members of the Micrococcaceae and Solirubrobacteraceae families, as well as the Conexibacter genus.
Non-metric multidimensional scaling (NMDS) analysis revealed that while specific microbial taxa shifted, the overall structure of bacterial and fungal communities remained stable across treatments.5 This suggests that MWCNTs were well tolerated by soil microbiota and may promote plant health without disrupting microbial balance.
CNTs for Sustainable Agricultural Practices by Plant Engineering
CNTs have been proven to be viable as nanocarriers for genetic materials, offering a potential alternative to traditional plant transformation methods such as Agrobacterium-mediated gene delivery. With a diameter of around 20 nm, CNTs can penetrate plant cell walls with ease, making them suitable for both gene delivery and targeted nutrient transport.
Functionalized, high aspect-ratio CNTs have been used to deliver plasmid DNA to various plant species, including wheat, cotton, and arugula. This method has enabled high expression of target proteins in non-model plant species, facilitating controlled gene expression and enhancing plant growth and resilience.
Beyond gene delivery, CNTs have also demonstrated utility as agricultural biosensors. Thanks to their high surface area, chemical stability, and rapid electron transport properties, CNT-based nanosensors can detect changes in soil pH, moisture levels, and the presence of pesticides or heavy metals with high sensitivity and specificity.
SWCNTs, in particular, are being explored for use in precision agriculture to monitor environmental conditions in real time and optimize crop management strategies.6
Outlook: Research Priorities and Responsible Use
CNTs have been applied to improve crop yield, enhance drought tolerance, and reduce heavy metal contamination in soil. However, the underlying mechanisms by which CNTs interact with plant systems and soil microbiota remain incompletely understood.
To close this gap, researchers are now applying computational tools to model CNT–soil–plant interactions more precisely. Ongoing work is also focused on evaluating the potential toxicity and environmental persistence of CNTs under real-world agricultural conditions.
These investigations will be essential for assessing the viability of CNTs as part of routine agricultural practice and ensuring their responsible integration into soil and crop management strategies.
To explore more developments in agricultural nanotechnology and soil engineering, visit:
References and Further Reading
- Natural Resources Conservation Service, U.S. Department of Agriculture. (2025). Soil Health. Natural Resource Concerns. [Online]. Available at: https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health [Accessed on: April 26, 2025].
- Zhang, C. et. al. (2021). Carbon nanotubes: A summary of beneficial and dangerous aspects of an increasingly popular group of nanomaterials. frontiers in oncology, 11, 693814. Available at: https://doi.org/10.3389/fonc.2021.693814
- Alam, K. et. al. (2022). Carbon nanotubes: Their role in the Modification of Soil Environment to Facilitate Sustainable Crop Production. Futuristic Trends in Agriculture Engineering & Food Sciences. IIP Proceedings. 2(9). Chapter 5. ISBN: 978-93-95632-65-2. Available at: https://www.researchgate.net/publication/378374338_CARBON_NANOTUBES_THEIR_ROLE_IN_THE_MODIFICATION_OF_SOIL_ENVIRONMENT_TO_FACILITATE_SUSTAINABLE_CROP_PRODUCTION
- Singh, G. et al. (2022). Role of multi-walled carbon nanotubes as a growth regulator for Basella alba (Malabar spinach) plant and its soil microbiota. Chem. Biol. Technol. Agric. 9, 71. Available at: https://doi.org/10.1186/s40538-022-00337-9
- Chen, X. et. al. (2022). When nanoparticle and microbes meet: The effect of multi-walled carbon nanotubes on microbial community and nutrient cycling in hyperaccumulator system. Journal of Hazardous Materials, 423, 126947. Available at: https://doi.org/10.1016/j.jhazmat.2021.126947
- Safdar, M. et al. (2022). Engineering plants with carbon nanotubes: a sustainable agriculture approach. J Nanobiotechnol 20. 275. Available at: https://doi.org/10.1186/s12951-022-01483-w
