Water-Smart Soil Using Biodegradable Polymers

Overview

This project investigates how three different biodegradable hydrogels - Agar, HydroxyEthyl Cellulose (HEC), and a blend of Agar + HEC can help absorb and retain water, slow evaporation and support plant growth. The goal was to explore simple, eco-friendly ways to conserve water in agriculture, especially during drought conditions. I predicted that Agar + HEC blend would perform best across all tests because combining two polymers might allow the soil to hold more moisture for longer periods. To test this, I prepared each hydrogel, soaked in water, and measured how much water they absorbed and how quickly they lost water over time. I then mixed the hydrogels into the soil, and recorded moisture levels daily for two weeks. Pea seeds were sowed in treated and untreated soil to compare germination and growth. The results showed that Agar + HEC blend absorbed the most water, while HEC alone kept the soil moist the longest. Agar dried the slowest but this was mainly because it absorbed very little water at the start. For seed germination, the Agar + HEC and Agar pots produced the strongest and healthiest seedlings while the control pots with no hydrogels had the weakest growth. Overall, the results partially supported my hypothesis: Agar + HEC was the best all round performer, showing strong absorption and excellent plant growth, even though HEC alone was slightly better at long-term moisture retention. These findings suggest how biodegradable hydrogels can help save water in farming and gardening and improve water efficiency in soil.

Competition history

• CSEF 2026 Environmental Engineering (Junior Division) · Entry J-11-08

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