Development of agar-alginate marine polysaccharides-based hydrogels for agricultural applications to reduce environmental hazards

In order to meet global food requirement, innovation in agricultural techniques and pesticide delivery system will be required for sustainable food supply with minimal harmful impact on environment. This article discusses the synthesis of hydrogels for use in controlled release formulations (CRFs) to increase agricultural output while reducing ecotoxicity and health risks. These hydrogels were designed by graft-copolymerization reaction of polyacrylamide and polyvinyl sulfonic acid onto agar-alginate marine polysaccharides. Copolymers were characterized by SEM, AFM, XRD, FTIR and ¹³C NMR. One gram of copolymeric hydrogels absorbed 14.80 ± 0.53 g of water. The glyphosate herbicide was released in a slow regulated manner over 72 h which is useful to avoid herbicide loss through leaching, evaporation and to reduce environmental hazards. The herbicide released via a non-Fickian diffusion mechanism and release profile was best described by the Korsmeyer-Peppas kinetic model. The release of herbicide from hydrogels occurred slowly and consistently in simulated soil conditions for a prolonged period. A soil adsorption studies of herbicide revealed a reduction in ground water ubiquity score (GUS) for glyphosate encapsulated hydrogels as compared to commercial formulations. Soil water retention was enhanced by the addition of hydrogel in the soil. The degradation of these CRFs can provide micronutrients (N and S) to improve soil quality and minimize the risk of water pollution by reducing the leaching of herbicides.