Synthesis and characterization of κ-carrageenan and guar gum-based hydrogels for controlled release fertilizers: Optimization, release kinetics, and agricultural impact

In this study, a hydrogel based on natural polysaccharides κ-carrageenan and guar gum was synthesized using epichlorohydrin as a crosslinking agent to evaluate its effectiveness as a slow-release fertilizer for urea and dipotassium hydrogen phosphate. Optimization studies revealed a maximum swelling capacity of 10610 %. The hydrogel synthesis was confirmed through various analytical techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Studies on the release kinetics of fertilizers from synthesized hydrogels were conducted at varying pH levels of 4, 7, and 9, maintained at a constant temperature of 37°C. The release kinetics of fertilizers were determined using different kinetic models. The application of hydrogels in agricultural practices has been shown to enhance non-leguminous plant growth significantly. In particular, soil amended with κ-CG-epi-GG hydrogels embedded with fertilizers demonstrated superior plant growth compared to untreated soil. The hydrogel's slow-release fertilizer properties, high swelling capacity, and sustained water retention ability render it an effective controlled-release system for fertilizers and a valuable soil conditioner in agricultural applications. • pH-responsive hydrogel was synthesized using κ-carrageenan and guar gum as the base materials. • Natural polysaccharides were utilized in controlled-release studies of fertilizers and research on plant growth. • Impact of incorporating hydrogel-based fertilizers on the growth of Lycopersicon esculentum can be investigated.