Food Waste-Derived Organic Fertilizers: Critical Insights, Agronomic Impacts, and Pathways for Sustainable Adoption

Food waste is one of the fastest growing sustainability challenges, wasting scarce resources and aggravating environmental degradation. Its valorization into organic fertilizers provides a critical opportunity to recover nutrients, reduce landfill burdens, and strengthen circular bioeconomy strategies. This review critically examines FW-derived organic fertilizers (FWOFs) across four major conversion routes including composting, vermicomposting, anaerobic digestion, and pyrolysis and also evaluates their impacts on soil health, nutrient cycling, crop yield and quality, and environmental trade-offs. We emphasize that while FWOFs offer multiple benefits, outcomes remain highly variable due to heterogeneity in feedstocks, processing methods, and application practices. Evidence highlights the strong potential for improving soil organic matter, water retention, and micronutrient supply but also raises unresolved risks from heavy metals, microplastics, and the survival of pathogens. By integrating multiscale evidence, this review provides a fertilizer-focused perspective that identifies critical knowledge gaps, standardization needs, and adoption pathways. In conclusion, this work underscores both the opportunities and limitations of FWOFs, offering concise guidance for advancing sustainable agriculture and circular bioeconomy practices.