DOM from eco-friendly fertilizers increases soil potential pathogen risk and shapes specific microbial populations under sprinkler and drip irrigation

Dissolved organic matter (DOM) released from eco-friendly fertilizer applications plays a crucial role in sustaining soil structure and function. However, the influence of eco-friendly fertilizer-derived DOM on soil properties and bacterial community structure under varying management practices remains inadequately understood. Therefore, DOM was extracted from biogas slurry (BSDOM), microbial fertilizer (MFDOM), and organic fertilizer (OFDOM) to investigate their effects on agricultural soil properties and bacterial community structure under sprinkler and drip irrigation through 90-day controlled indoor experiments. Results showed that the source and composition of DOM, especially its aromaticity and molecular weight, significantly influenced both soil properties and bacterial community structure. In contrast, the irrigation method exerted a relatively minor effect, primarily impacting core functional bacterial groups within the microbial community. The concentration of DOM applied via irrigation predominantly significantly influenced soil properties. Notably, BSDOM irrigation markedly enhanced the abundance of ammonia-oxidizing bacteria, contributing to soil nitrogen cycling, while MFDOM and OFDOM irrigation promoted bacteria associated with carbon cycling while enhancing populations of organic matter-degrading symbiotic bacteria. Moreover, the proliferation of potentially pathogenic bacteria alongside mobile genetic elements during DOM irrigation raises concerns regarding soil health and the potential dissemination of antibiotic resistance genes. These findings underscore the necessity for considering the complex interactions between fertilizer composition and water management strategies. • DOM input level shaped soil properties, while type impacted microbial communities. • BSDOM irrigation favored N cycling, while MFDOM and OFDOM preferred C cycling. • Irrigation methods influenced the core function of microbial community bacteria. • DOMs irrigation increased the risk of potential pathogenic bacteria. • DOM aromaticity and molecular weight affected bacterial community structure.