Form dictates function: Component-specific remediation mechanisms of compost in tetracycline-contaminated soil

To design precise remediation strategies for tetracycline-contaminated soils, a mechanistic understanding of how different compost components regulate the soil-plant-microbe system is essential, yet remains unclear. Therefore, this study systematically evaluates the distinct effects of three compost components-solid compost (SC), compost extract (CE), and compost tea (CT)-at four application rates (1%, 5%, 7%, 10%) on tetracycline dissipation, soil properties, plant growth, and microbial communities through a 120-day ryegrass pot experiment. All compost amendments significantly enhanced tetracycline (TC) removal compared to the control. CT demonstrated the highest dissipation efficiency (63.13%) and rate constant at 7% application rate, highlighting its capacity for rapid decontamination. In contrast, SC (10%) most effectively improved soil health by significantly increasing available phosphorus content (46.0 ± 0.58 mg/kg) and promoted plant biomass and root elongation. CE and CT preferentially enhanced cation exchange capacity. Microbial analysis revealed that compost addition reshaped bacterial community structure, enriched potential degraders such as Bacillus (Firmicutes), and notably, CE treatment formed the most complex bacterial co-occurrence network. These findings demonstrate that the physical form of compost components dictates their primary remediation function, establishing a clear form-function relationship. CT facilitates rapid pollutant reduction through microbially-mediated pathways, whereas SC enables sustained soil improvement and ecological restoration. Consequently, this component-specific functional framework provides a rational basis for targeted remediation strategies-using CT for rapid decontamination or SC for long-term soil health-thereby advancing the precision and sustainability of bioremediation in antibiotic-contaminated agroecosystems.