Design and Characterization of Biodegradable Polysaccharide/Humic Acid Hydrogels for Sustainable Applications

Water scarcity remains one of the most critical challenges affecting agricultural productivity in arid and semi-arid regions. Hydrogels, as three-dimensional polymeric networks, have attracted increasing attention as soil conditioners due to their ability to retain water and act as carriers for nutrients or bioactive compounds. However, most commercial hydrogels are derived from synthetic polymers such as polyacrylates, which are not readily biodegradable and may generate environmental concerns. This has stimulated research into bio-based and biodegradable alternatives that combine high water retention with environmental compatibility.

In this study, we designed and developed superabsorbent hydrogels based on gellan gum (GG), karaya gum (KG), and humic acid (HA) as sustainable systems for agricultural applications. The hydrogels were characterized by means of FTIR, TGA, SEM, mechanical assays, and swelling kinetics. Soil water retention assays demonstrated that GG/HA and GG/KG/HA formulations preserved higher moisture levels than a commercial polyacrylate hydrogel. Biodegradation studies confirmed their environmental compatibility, showing weight losses greater than 30% after 30 days in soil extract.

Biological trials with sorghum (Sorghum sp.) seedlings under controlled chamber conditions (27±1 °C, 12 h photoperiod) revealed no phytotoxicity. Moreover, the GG/KG/HA hydrogel promoted superior growth and chlorophyll accumulation compared to GG/HA, highlighting the synergistic role of KG and HA in stimulating plant development.

These results confirm that GG/KG/HA hydrogels are biodegradable, biocompatible, and effective soil conditioners, offering a sustainable pathway to improve water-use efficiency, soil quality, and crop productivity.