Researchers at the University of Seville have developed a biodegradable gel that can absorb up to 60 times its weight in water. This innovation aims to help farmers maintain soil moisture during severe droughts, using natural materials instead of petrochemical products.
In Seville, a team of scientists has engineered a biodegradable hydrogel capable of absorbing and retaining extraordinary amounts of water—up to 60 times its own weight. Designed to address the growing challenge of drought in agriculture, this new material could offer a lifeline to crops struggling with water scarcity.
The hydrogel is crafted from chitosan and alginate, two natural compounds sourced from shrimp shells and seaweed. When dry, the material resembles a sponge. Once hydrated, it transforms into a gel-like network that traps water, making it available to plant roots over time. This property is especially valuable in regions where rainfall is unpredictable or insufficient.
Natural Alternative to Synthetic Hydrogels
Traditional hydrogels used in agriculture are often derived from petrochemicals and can persist in the environment long after their usefulness ends. The University of Seville’s approach replaces these with marine-based, biodegradable ingredients. Chitosan, extracted from crustacean shells, provides structural strength, while alginate from seaweed enhances water absorption. The combination results in a balanced formulation tailored for agricultural use.
Calcium is added to reinforce the gel’s structure, improving its stability and ensuring it maintains its shape and water-holding capacity even when fully hydrated. This makes the material robust enough for real-world farming conditions.
Testing and Performance
To evaluate the gel’s effectiveness, researchers prepared three different mixtures: one with chitosan, one with alginate, and one combining both in equal parts. The mixtures were transformed into gels by adjusting the pH and adding calcium chloride, which helped solidify the final structure.
The resulting material is moist and flexible, with a texture similar to gelatin. After freeze-drying, it develops a porous structure that rapidly swells when exposed to water, acting as a miniature reservoir within the soil. Laboratory analysis showed that the chitosan-alginate blend offered the best balance of strength and absorption, retaining between 40 and 60 times its own weight in water. The gel also remained stable at temperatures up to 40°C, a critical threshold for many agricultural soils in southern Spain.
Next Steps: Integrating Nutrients and Field Trials
The study, published in the Journal of Environmental Chemical Engineering, addresses several pressing issues in agriculture: declining soil fertility, water shortages, and the overuse of chemical additives. The hydrogel can absorb water from irrigation or rainfall and gradually release it as the soil dries, helping to buffer crops against drought stress.
Researchers are now exploring ways to load the gel with natural fertilizers or micronutrients, allowing for slow, controlled release into the soil. Before the material can be adopted on a large scale, the team plans to test its performance under real farming conditions, including different soil types, irrigation water, salinity, and acidity levels.
Environmental safety is also a priority. The gel’s biodegradability and potential ecotoxicity will be thoroughly assessed to ensure it poses no risk to ecosystems. The project has received funding from the Junta de Andalucía, European funds, and Spain’s Ministry of Science, Innovation and Universities through the State Research Agency.
As climate change intensifies drought cycles across southern Europe, innovations like this hydrogel could play a crucial role in sustaining agricultural productivity while reducing reliance on synthetic chemicals. If successful in field trials, the technology may offer a practical, eco-friendly solution for farmers facing increasingly harsh conditions.
