Valorization of Banana Peels and Agricultural Residues for Sustainable Biofertilizer: Advances in Waste Utilization and Microbial Enhancement

Abstract

Banana peels (BPs), a widely generated agro-waste, possess substantial nutritional, structural, and bioactive properties that remain underutilized in agricultural systems. Their valorization into biofertilizers has gained significant attention due to the growing need for low-cost, eco-friendly alternatives to synthetic fertilizers. BPs contain high levels of potassium, calcium, polyphenols, pectin, carbohydrates, and lignocellulosic compounds that make them suitable for conversion into multiple value-added products, including compost, liquid extracts, biochar, pectin gels, antioxidant powders, and biodegradable packaging materials. Recent advances demonstrate that integrating microbial inoculants—such as Bacillus, Azotobacter, Trichoderma, and phosphate-solubilizing bacteria—enhances decomposition, improves nutrient mineralization, and enriches the final fertilizer quality. Furthermore, BP-derived amendments have been reported to improve seedling vigor, biomass accumulation, soil enzyme activities, and resistance to abiotic stress in several crops. The review highlights current valorization approaches, chemical attributes influencing product efficiency, microbial mechanisms involved in residue transformation, and the potential role of BP-based fertilizers in supporting circular bioeconomy frameworks. Key challenges include achieving consistency in nutrient composition, optimizing fermentation parameters, and establishing regulatory standards. Overall, BP valorization provides an accessible, sustainable, and scalable pathway for transforming agricultural residues into high-value biofertilizers that can significantly enhance soil health and reduce dependence on chemical inputs.