Keratin-Integrated Latex–Hydrogel Coatings: Biopolymer Design for Functional Agrotextile Materials

This work introduces a circular biopolymer-based strategy for valorizing keratin-rich industrial residues through the fabrication of biodegradable cotton agrotextiles functionalized with latex–hydrogel coatings. Keratin hydrolysates and gelatin-derived biofertilizer capsules were incorporated into polymer–hydrogel matrices and applied onto cotton substrates to enhance soil moisture regulation and controlled nutrient release. The composite coatings were characterized in terms of water absorption capacity, mechanical performance, biodegradation profiles, and their impact on plant growth using Phaseolus vulgaris as a model species. Hydrogel-rich formulations (LH20 and LH40Z) provided the most favorable balance of tensile strength and controlled degradation while significantly increasing soil moisture availability and overall plant biomass compared with uncoated controls. The gelatin–keratin microcapsules enabled sustained nutrient release and induced a slight increase in soil pH, further supporting plant development. These findings demonstrate the dual functionality of the developed latex–hydrogel coatings as water-management and nutrient-delivery systems and highlight the potential of keratin biowaste upcycling toward high-value, biodegradable agricultural materials aligned with circular economy principles.