Developing high-efficiency green fertilizers from poultry manure Using N-acetylcysteine for enhanced nitrogen retention and agronomic performance

Abstract

In this research, tomato plants were used to assess the effects of N-acetyl-L-cysteine (NAC) on the decomposition dynamics and agronomic properties of poultry manure through combined physicochemical and biological evaluations, supported by LC-MS metabolite profiling. Control treatments, consisting of untreated manure, exhibited low microbial activity, restricted nutrient availability, and elevated levels of phytotoxic compounds such as butyric acid, phenol, and indole, particularly at manure concentrations exceeding 40%.In contrast, NAC-treated samples demonstrated enhanced microbial diversity, accelerated organic matter breakdown, and significant suppression of toxic short-chain fatty acids. LC-MS analysis revealed the appearance of sulfur-containing metabolites, including free thiols, indicating the establishment of a redox-buffered environment that improved nitrogen bioavailability and mitigated oxidative stress. These changes correlated with a remarkable increase in plant biomass—exceeding tenfold compared to the control—and eliminated growth inhibition even at high manure concentrations. Furthermore, NAC contributed to heavy metal detoxification via thiol-mediated chelation, ensuring root zone safety and improved soil health. Overall, this study establishes NAC as an effective additive that transforms raw poultry manure into a stable, nutrient-rich, and environmentally safe fertilizer. The integration of physicochemical and biological assessments with LC-MS diagnostics provides strong evidence for the role of biochemical modulation in enhancing manure quality. This approach offers a scalable strategy to improve crop productivity while minimizing environmental risks, thereby supporting sustainable organic agriculture.