Incorporating Ginger Extract as a Bioactive Additive Into Eco-Friendly Fertilizer Coatings Based on Natural Rubber-Grafted-Rice Starch: A Performance Evaluation

Abstract

A polymeric coating was developed to minimize fertilizer loss and improve antifungal efficacy against Fusarium sp. by combining natural rubber-grafted rice starch (NR-g-ST) with methanolic ginger extract (GE) for coating granular urea fertilizer. The coating was synthesized via in situ graft copolymerization, employing potassium persulfate as an initiator within an emulsion system. Fourier transform infrared (FT-IR) spectroscopy confirmed successful grafting and molecular interactions between the hydroxyl groups of starch with both GE and natural rubber (NR). The NR:ST ratio was maintained at 70:30 wt%, while GE content was varied from 0 to 9 wt% relative to the polymer matrix. The coatings were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and water contact angle (WCA) measurements. Increasing GE content enhanced the mechanical properties, storage modulus, and hydrophobicity while reducing biodegradability. The coating demonstrated antifungal efficacy through the inhibition of Fusarium sp. mycelial growth, suggesting its potential as a multifunctional agricultural solution.