Synthesis and Characterization of Ionically-Crosslinked <i>κ</i>- Carrageenan/Sodium Alginate/Carboxymethyl Cellulose Hydrogel Blends for Soil Water Retention and Fertilizer Release

Providing enough water in farming has become a challenge in the Philippines due to insufficient irrigation and escalating drought conditions, thereby decreasing agricultural productivity. The impact of this problem can be lessened through efficient water usage: by reducing water wastage in runoff or evaporation and improving soil water retention. Hydrogels can be used for this purpose due to their water absorption capabilities. In this study, a novel, biodegradable agricultural hydrogel was developed from κ-carrageenan, sodium alginate and carboxymethyl cellulose, crosslinked with Ca 2+ and K + ions. Scanning electron microscopy analysis confirmed the successful crosslinking while swelling tests revealed them as superabsorbent hydrogels, with maximum absorption reaching 2000%. Soil amended with 2% (w/w) hydrogel showed reduced water-depletion rate and improved field capacity by a maximum of 17.6% and 17.4%, respectively. Fertilizer release test also showed the potential of these hydrogels as fertilizer carriers.