Natural Organic Compounds in Organic Farming: Roles, Mechanisms, and Future Prospects – A Narrative Review

Natural organic compounds (NOCs) derived from plant, animal, microbial, and mineral sources are increasingly recognized as key inputs for sustainable and eco-friendly agricultural systems. These bioactive compounds enhance soil fertility, regulate plant growth, and manage pests and diseases while reducing reliance on synthetic agrochemicals. This narrative review critically synthesizes current knowledge on the classification, mechanistic pathways, and agronomic applications of NOCs within organic farming frameworks. Emphasis is placed on plant- and microbe-derived compounds such as allelochemicals, humic substances, and amino acid hydrolysates, which function as biofertilizers, biostimulants, and biopesticides by modulating nutrient cycling, soil microbial dynamics, and plant stress resilience. Mineral-associated organic compounds, including humic and fulvic acids, further contribute to soil structural stability and nutrient retention. Although numerous studies report yield improvement and enhanced agroecosystem sustainability following NOC application, the evidence base remains constrained by heterogeneous methodologies, variable efficacy across environments, and limited long-term field validation. By integrating mechanistic insights with agronomic outcomes and emerging analytical approaches, this review identifies key limitations, regulatory and standardization challenges, and priority research directions. Future progress will depend on harmonized analytical frameworks, field-scale validation, and scalable formulations aligned with circular bioeconomy principles to enable reliable and widespread adoption of NOCs in sustainable crop production.