Agriculture is under pressure to produce more food while using fewer fossil-derived fertilizers, pesticides, and plastics. A new review in Carbon Research highlights an abundant but underused material that could help reshape the way farms deliver nutrients, protect crops, and manage soil: lignin. Best known as the tough structural polymer that gives wood its strength, lignin is generated in enormous quantities by the pulp, paper, and biorefining industries. The review, led by Hongliang Wang of China Agricultural University, examines how this carbon-rich biomass residue could be transformed into a new generation of agricultural materials.
Lignin is particularly attractive because it is not simply a passive filler. Its complex aromatic structure contains phenolic and aliphatic hydroxyl groups that can participate in chemical reactions and bind with other substances. The polymer also absorbs ultraviolet radiation, displays antioxidant and antimicrobial activity, and can be engineered to degrade at different rates. These characteristics give lignin an unusually broad technological range, allowing it to function in coatings, hydrogels, particles, films, and composite materials. Instead of burning or disposing of lignin as a low-value by-product, manufacturers could potentially convert it into products designed to make agricultural inputs more efficient and less polluting.
One major opportunity involves controlled-release fertilizers. Conventional fertilizers can dissolve rapidly, allowing nitrogen and other nutrients to escape through runoff, leaching, or volatilization before plants can absorb them. Lignin can be used as a coating or incorporated into a nutrient-carrying matrix to create a physical barrier around fertilizer granules. Water and dissolved nutrients then move more slowly through the material, extending nutrient availability and potentially improving nitrogen-use efficiency. Chemical modification can further alter lignin’s swelling, solubility, and binding behavior, making it possible to tune how quickly nutrients are released under different soil conditions.
Lignin-based materials could also become multifunctional soil amendments. When combined with hydrophilic polymers or other components, lignin can form hydrogels and porous composites capable of retaining water and releasing it gradually near plant roots. Such materials may help reduce irrigation demand and limit nutrient loss in drought-prone soils. Lignin’s functional groups can also interact with metal ions, raising the possibility of using lignin-containing composites to immobilize or capture contaminants. By improving water retention, soil aggregation, and chemical stability, these materials could support crops exposed to salinity, drought, or degraded soil conditions.
The review also explores lignin as a delivery platform for pesticides. Many active ingredients used in crop protection have poor water solubility, degrade under sunlight, or disperse unevenly across fields. Lignin-based particles, emulsions, and coacervates can encapsulate these compounds, shielding them from ultraviolet radiation and helping them disperse more effectively. The structure of the carrier can be designed to release its payload gradually or respond to environmental triggers such as pH, moisture, or enzymatic activity. In principle, this could maintain effective concentrations near target organisms while reducing the amount of pesticide that reaches surrounding soil and water.
Another potential application is in agricultural films and seed coatings. Plastic mulch films can conserve moisture and suppress weeds, but their persistence creates a major waste problem when fragments remain in soil. Lignin can contribute UV protection, biodegradability, and mechanical reinforcement to mulch films and sprayable coatings. It may also be incorporated into paper-based mulches or seed-coating formulations, where it can help regulate moisture transfer and protect seeds during early development. The combination of sunlight absorption and natural antimicrobial activity could make lignin useful in materials designed to protect seeds and young plants without relying entirely on conventional plastics.
However, the review stresses that lignin is not a standardized substance. Its molecular composition varies according to plant species, cultivation conditions, and the industrial process used to extract it. Differences in molecular weight, aromatic linkages, functional groups, solubility, and branching can significantly affect how lignin behaves in a coating or composite. Two batches described simply as “lignin” may therefore perform very differently. This variability can complicate film formation, chemical modification, manufacturing consistency, and the prediction of how a product will behave after it enters soil.
To improve reliability, researchers are developing methods to separate lignin into more uniform fractions or modify its molecular structure. The review discusses solvent fractionation, gradient acid precipitation, membrane filtration, ionic-liquid processing, chemical derivatization, grafting, and depolymerization. These approaches can adjust lignin’s reactivity, particle size, solubility, and interaction with nutrients or pesticides. The authors emphasize the importance of linking molecular structure to material properties and then to real agricultural performance. Such structure–property–performance relationships could allow manufacturers to select or engineer lignin for a specific task rather than treating it as a one-size-fits-all ingredient.
Moving from laboratory demonstrations to working farms will require more than promising chemistry. The authors identify unresolved questions about long-term environmental fate, degradation products, ecological safety, production costs, and compatibility with existing equipment and farming practices. Much of the current evidence comes from laboratory experiments or greenhouse trials, while agricultural products must withstand changing weather, mechanical stress, microbial activity, and repeated exposure to soil and water. Lignin-derived alternatives may also remain more expensive than established materials such as conventional fertilizer coatings, lime, or plastic mulch until production reaches a larger scale.
The review presents lignin valorization as part of a wider transition toward circular, low-carbon agriculture rather than as a single solution to the sector’s environmental challenges. The authors call for standardized structural fingerprints for industrial lignin, predictive models, greener processing methods, and long-duration field studies that monitor soil health, degradation products, crop responses, and non-target organisms. They also point to emerging connections with nanotechnology, plant microbiomes, and responsive delivery systems. If those scientific and engineering barriers can be overcome, a material once treated largely as industrial residue could become a versatile platform for fertilizers, soil conditioners, crop-protection systems, films, and seed coatings—turning biomass waste into tools for a more resource-efficient food system.
Article Title: Lignin valorization toward eco-friendly agricultural inputs
News Publication Date: 6-Aug-2026
Web References: https://doi.org/10.1007/s44246-026-00294-0
References: Wang, Hongliang, et al. “Lignin valorization toward eco-friendly agricultural inputs.” Carbon Research. DOI: 10.1007/s44246-026-00294-0
Image Credits: Xinran Zhang, Yitong Wang & Hongliang Wang
Keywords: lignin, sustainable agriculture, controlled-release fertilizers, soil amendments, pesticide delivery, agricultural films, seed coatings, biomass valorization, biodegradable materials, soil carbon, circular agriculture, environmental chemistry
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