Effects and mechanisms of kitchen waste organic fertilizers application on soil nitrogen transformation, plant pathogenic virulence genes, and metabolites

The application of organic fertilizers enhances soil fertility and alters the function and structure of the soil microbial communities. When subjected to aerobic composting, kitchen waste is transformed into organic fertilizer. However, the ecological benefits and safety risks of kitchen waste organic fertilizers (OF) in soil require further evaluation. Therefore, this study conducted a pot experiment to investigate the effects and mechanisms of OF application on soil properties, crop growth, nitrogen transformation, plant pathogenic virulence genes, and metabolites. The results indicated that OF treatment promoted vitamin C synthesis in pakchoi (35.23-48.00 %) and reduced soil N2O emissions during cultivation compared with inorganic fertilizer (IF) (65.50-68.08 %) (P<0.01). IF treatment significantly increased the abundance of Rhodanobacter (6.41 %) and Nitrobacter (3.16 %), leading to increased N2O emissions (17.94 mg kg(-1)). Key nitrogen metabolism enzymes and functional genes indicated that nitrification and denitrification pathways were the primary contributors to N2O production. Metagenomic results revealed that IF treatment enhanced virulence gene pathogenicity through quorum sensing (QS), whereas OF treatment reduced virulence gene accumulation in plant pathogenic bacteria. Metabolomic analysis demonstrated that OF treatment significantly upregulated substances beneficial to soil activity and plant growth, while inhibiting pollutant expression. PLS-PM results indicated that soil properties played a pivotal role in shaping the intricate relationships among microbial communities, functional genes, and substance metabolism. This study demonstrated that OF application contributed to the promotion of plant health and optimization of soil ecosystems, thereby providing theoretical support for the further expansion of OF applications in agriculture.