The static and cidal effects of veterinary antibiotics on soil microorganisms in the presence of organic and mineral amendments

• Gentamicin initially decreased microbial activity comparative to penicillin higher. • Recovery was comparatively high in oxytetracycline treated soils. • Organic amendments improved the resilience indices. • Unexpectedly the qCO2 decreased in the antibiotic treated soils. • The static effects of the applied antibiotics were higher than their cidal effects. This study aimed to describe the static and cidal adverse effects of antibiotics on soil microbial activity resulting from manure application. So, in the present study, the treatments included: without antibiotics; application of gentamicin, oxytetracycline, and penicillin each in different concentrations (50, 100, and 200 mg kg−1 dry soil). They were applied in soils treated with and without organic and mineral conditioners (cow manure, biochar, and nano-zeolite). Soil microbial respiration and metabolic quotient were studied at three time periods (1–7, 7–30, and 30–90 days) during a 90-day incubation of the treated soils. Antibiotics applied to the soil samples significantly decreased soil basal respiration (BR) values compared to those of the control, and the most significant decrease was observed for gentamicin. Gentamicin had a short intensive impact, alleviated by manure and biochar, on soil copiotrophs. After a significant initial reduction in substrate-induced respiration (SIR), gentamicin application then caused a substantial increase in SIR values. Unexpectedly metabolic quotient decreased in the antibiotic-treated soils. This study revealed that the static effects of the applied antibiotics in soil were greater than the cidal effects.