Synthesis of biodegradable starch-based superabsorbent hydrogels for agricultural applications

This research synthesized biodegradable superabsorbent hydrogels from cassava starch grafted with acrylic acid using ammonium persulfate as initiator and N,N′-methylenebisacrylamide as crosslinker, then evaluated their water retention performance under simulated arid agricultural conditions. The graft copolymerization was confirmed by FTIR spectroscopy, and thermal stability was assessed through TGA and DSC. The optimized hydrogel (SH-4, starch-to-monomer ratio 1:4, 0.5 wt% crosslinker) achieved a maximum swelling capacity of 487 g/g in distilled water and 68 g/g in 0.9% NaCl solution, with 91% biodegradation after 90 days of soil burial. Pot experiments with date palm seedlings showed that soil amended with 0.5 wt% hydrogel retained 2.3 times more moisture at 14 days post-irrigation compared with unamended control soil. Seedling root length and shoot biomass increased by 34% and 28%, respectively, over 60 days. These findings demonstrate that starch-based superabsorbent hydrogels offer a practical, environmentally benign strategy for improving water-use efficiency in arid-zone agriculture.