Degradation of tetracycline, sulfamethazine, and tylosin in soil from prairie strips and row crops in Iowa

Abstract

The livestock industry in the United States relies on antibiotics for disease prevention and treatment. As a result, antibiotic-laden manure is frequently applied to farmland to recycle nutrients. In the soil environment, antibiotics may accumulate and create selective pressure for antibiotic resistance in bacteria or travel to nearby water resources. This in vitro incubation study evaluated whether prairie buffer strips on farmland enhance degradation of three antibiotics-tetracycline, sulfamethazine, and tylosin-compared with degradation in soil from row crops adjacent to the strips.Soil from prairie strips of varying establishment ages and adjacent row crops were evaluated from three central Iowa sampling locations. Antibiotics mixed with swine manure slurry were added to soils at a starting concentration (10 μg kg -1 ) that reflects common veterinary antibiotic concentrations in soil and runoff after manure application. Antibiotic concentrations were quantified at six time points throughout a 72-d incubation period and fit to a first-order model to calculate decay rate constants and half-lives. The mean half-life for tetracycline was 0.54 d longer in prairie strip soil than row crop soil, whereas sulfamethazine and tylosin demonstrated no significant difference in persistence in strip or crop soil. Time since the establishment of the prairie strip did not affect antibiotic persistence. Concentrations of each antibiotic decreased to near-background levels throughout the incubation period. This study suggests that prairie strips do not consistently enhance antibiotic degradation in farm fields, but that antibiotics are unlikely to persist throughout the growing season in soil under strip or crop management.

Vegetative buffer strips show limited effectiveness for reducing antibiotic transport in surface runoff

“…The presence of veterinary antibiotics (VA) in water resources and drinking water supplies continues to be a substantial environmental issue affecting human and aquatic ecosystem health (Barrios et al., 2020; Brown et al., 2015). Surface water runoff from manured agroecosystems is considered a primary mechanism for VA transport to surface waters (Hall et al., 2020; Iverson et al., 2022; Lin et al., 2011), and surface runoff events are more problematic for soils with water‐restrictive subsoil horizons such as claypans (Anderson et al., 2009; Liu et al., 2020). The presence of such water‐restrictive subsoil horizons results in more frequent surface runoff events, greatly increasing the risk of pesticides and VA transport to surface water resources (Lerch and Blanchard, 2003; Udawatta et al., 2006).…”

Evaluation of prairie strips to mitigate the dissemination of antibiotic resistance contaminants from agroecosystems to the environment

“…Application of this manure to a field represents a direct route of tetracycline exposure to environmental bacteria and any form of repeated manure application highlights the potential for antibiotic accumulation within soils. Furthermore, antibiotics with a high Kd, such as tetracycline, can be resistant to biodegradation resulting in widely varying half-lives depending on the environmental system (Iverson et al, 2021;Lin et al, 2010;Pan & Chu, 2016). Currently, no standard protocol exists to analyze the presence of antibiotics within different environmental matrices and no regulatory guidelines exist to label high concentrations of antibiotics as a form of environmental pollution (Polianciuc et al, 2020).…”