As climate change, soil degradation, and water scarcity place growing pressure on agriculture, scientists are looking for new ways to help crops germinate and grow more efficiently while reducing environmental impact. A new study involving researchers from Nazarbayev University’s National Laboratory Astana proposes a promising solution: biodegradable hydrogel coatings made from natural polymers.

The research focuses on hydrogel formulations based on starch and carboxymethyl cellulose, two renewable and biodegradable materials. These hydrogels are designed to absorb and retain water, then gradually release it around seeds during germination. In agricultural settings, this function is especially important for dry or water-limited soils, where early seedling development can be highly vulnerable.

Unlike many conventional superabsorbent materials, which are often derived from petroleum-based polymers, the newly developed hydrogels contain a high bio-based content. The team synthesized hydrogels using different ratios of starch and carboxymethyl cellulose and evaluated their structure, swelling behavior, biodegradability, and effect on sugar beet seed growth.

The results showed that the hydrogels could absorb up to 17.5 grams of water per gram of material. Their porous structure, confirmed through scanning electron microscopy, supported water uptake, while spectroscopic analysis confirmed the formation of a stable crosslinked polymer network. Importantly, the materials also showed strong biodegradability, with around 67% degradation in soil during the study period.

When applied as part of a seed coating system, the hydrogel formulations improved the growth of sugar beet seedlings. Coated seeds demonstrated significantly better seedling emergence compared with uncoated seeds, with the best-performing coating combinations reaching seedling lengths of about 6 cm, compared with around 3 cm for untreated seeds.

The study also explored the use of wood ash in the coating composition. Wood ash can provide essential minerals such as potassium, calcium, and phosphorus, while the hydrogel helps retain moisture and support gradual delivery around the seed. Among the tested coating approaches, the ash–polymer–ash structure showed particularly promising results.

The authors note that further research is needed to optimize the formulation for mechanical stability, long-term field performance, and environmental safety, including additional assessment of residual crosslinking agents. However, the findings suggest that starch–CMC hydrogels could become a viable platform for sustainable seed coating, water-retaining soil conditioners, and potentially controlled-release agricultural systems.

• The team developed biodegradable starch - carboxymethyl cellulose hydrogels with high bio-based content.
• The hydrogels absorbed up to 17.5 g/g of water.
• The materials showed approximately 67% degradation in soil.
• Hydrogel-coated sugar beet seeds showed improved seedling growth compared with uncoated seeds.
• The approach may help reduce dependence on petroleum-derived superabsorbents in agriculture.

Seed coating technologies are increasingly important for sustainable agriculture because they can improve germination, protect young seedlings, and support more efficient use of water and nutrients. By using biodegradable materials derived from natural polymers, this research contributes to the development of agricultural inputs that are both functional and environmentally responsible.

For regions facing water scarcity or soil degradation, such materials may help improve crop establishment while reducing pollution associated with persistent synthetic polymers.

Article title: Biopolymer-based hydrogel formulations for improved seed coating performance
Journal: Scientific Reports
DOI: https://doi.org/10.1038/s41598-025-30594-1
Authors: Raikhan Rakhmetullayeva, Botakoz Khavilkhairat, Assel Toktabayeva, Nurzhan Mukhamadiyev, Elmira Nurgaziyeva, Munziya Abutalip
Affiliations: Al-Farabi Kazakh National University; Kazakh Research Institute of Plant Protection and Quarantine; National Laboratory Astana, Nazarbayev University