The unintended patient: How do antibiotic residues in animal manure affect soil nitrogen cycling?

Animal manure is a common agricultural fertilizer, but it often introduces residual veterinary antibiotics into soil ecosystems. This thesis investigates the consequential effects of these antibiotic residues on vital soil nitrogen cycling processes. Findings reveal that these veterinary medicines could alter soil nitrogen dynamics in highly specific ways, dependent on both the type of antibiotic and the soil profile. These residues can temporarily inhibit some nitrogen transformation pathways or, unexpectedly, stimulate the growth of certain soil microbes. Furthermore, grassland plant species exhibit differential tolerance to antibiotic residues. Clover exhibited high sensitivity, whereas ryegrass was relatively resilient. Ultimately, this research highlights that predicting the ecological impacts of antibiotic residues requires a comprehensive understanding of complex soil-plant-antibiotic interactions. Consequently, preventing veterinary antibiotics from entering ecosystems emerges as the most pragmatic way of mitigating these environmental risks.