Lignin-based hydrogels for application in agriculture: A review

Agriculture is an important sector for maintaining environmental sustainability and ensuring global food security. However, the sector faces significant challenges caused by soil degradation, water scarcity, and resource limitations. To overcome the challenges, several studies have shown that innovative materials, including hydrogels, have the ability to improve agricultural practices. Lignin, the sole polyaromatic biopolymer, and the second most abundant biopolymer, has been extensively explored for a wide range of applications. For example, lignin valorization represents a significant issue for lignocellulosic biorefineries as well as the pulp and paper industry. This has led to an increase in interest over the past decade in its utilization to create innovative, advanced smart materials. Therefore, this study aims to discuss the applications, advantages, and possibilities of lignin-based hydrogels in addressing the primary difficulties of contemporary agriculture to increase sustainability. The initial section of the study discussed the introduction of lignin and its isolation methods, followed by an in-depth examination of polymeric hydrogels, encompassing their composition and applications in agriculture. The third section focused on lignin-based hydrogels, detailing preparation procedures for their primary application in agriculture. This study also analyzed the progress in lignin-based hydrogels over the past decade and provided a relevant assessment of the promising material.