Multifunctional xanthan gum/wood fibers based hydrogels as novel topsoil covers for forestry and agricultural applications

This study was focused on the development of novel bio-based and biodegradable hydrogels constituted of Xanthan gum (XG) reinforced with wood fibers, to be used as eco-sustainable topsoil covers (TSCs) in support of reforestation and agricultural efforts in arid conditions. At this aim, hydrogels were developed by cross-linking XG with citric acid (CA), sodium trimetaphosphate (STMP) or tannic acid (TA) at different concentrations. Samples cross-linked with CA and TA exhibited the highest dimensional stability and exceptional water absorption capability, even after multiple absorption/drying cycles. Hydrogels with 50, 60, and 100 phr of CA displayed water vapor permeance values of about 9.5·10−6 g/(Pa·s·m2), i.e., comparable to commercial woven PP mulching films. The average penetration resistance of the produced hydrogels was twice that of the commercial one. The presence of wood fibers in the hydrogels provided dimensional stability and minimal shrinkage after exposure to outdoor conditions for two months (15.4% for sample with 60 phr of CA). Furthermore, after 7 months of exposure, more than 60% of the sample mass was biodegraded. This research demonstrated the potential of Xanthan gum/wood fibers based hydrogels as TSCs with superior water-regulating properties, thus offering a simple, cost-effective and scalable technology for forestry and agriculture applications.