Biodegradable hydrogels of tragacanth gum polysaccharide to improve water retention capacity of soil and environment-friendly controlled release of agrochemicals

Abstract

This work reports the synthesis of lipase enzyme catalyzed biodegradable hydrogel interpenetrating polymer network (hydrogel-IPN) of natural gum polysaccharide i.e. gum tragacanth (GT) with acrylamide (AAm) and methacrylic acid (MAA) and their potential application in the delivery of agrochemicals. Biodegradation experiments were performed using composting and soil burial methods of biodegradation. Complete degradation of synthesized hydrogel-IPN occurred within 77 days using composting method, while using soil burial method 81.26% degradation occurred after 77 days. Furthermore, effect hydrogel-IPN degradation on the fertility of soil was also studied through macro-analysis of soil. Water retention capacity of clay soil and sandy loam soil was improved after mixing swelled sample of hydrogel-IPN with these soil samples. The potential of hydrogel-IPN was also tested for sustained and slow release of two agrochemicals i.e. urea and calcium nitrate. Kinetics of agrochemicals release revealed that the release rate of both the fertilizers was initially higher which kept on decreasing with time. Diffusion mechanism of agrochemicals followed Case-II diffusion type behavior. Therefore, synthesized hydrogel-IPN is important from agriculture view point and can be used for sustained and controlled release of agrochemicals.

Keywords: Agrochemicals release; Biodegradation; Hydrogel polymers; Water retention.