The use of antibiotics in animal agriculture has exacerbated the presence of both antibiotic resistance genes (ARGs) and residual antibiotics found excreted in animal manure. Application of this manure to crop fields is a common practice as its nutrient rich material can benefit crop growth; however, field application can also introduce antibiotics and ARGs into non-agricultural settings. The integration of prairie buffer strips within and at the edge of crop fields are a potential management solution to reduce the movement of antibiotics and ARGs present in water runoff from manured fields. We investigate the fate and persistence of antibiotics and ARGs in directly manured crop field soils and the surrounding, impacted prairie strip soils. An incubation experiment was conducted in which row crop (corn and soybean) soil or prairie strip soil was mixed with a swine manure slurry spiked with antibiotics. Monitoring of the measured concentrations of antibiotics and characterization of the microbial communities of the manure and soil samples over a 72-day period in three different pairs of crop and prairie strip soils was conducted to better understand the fate of introduced ARGs and the rate of degradation of introduced tetracycline, sulfamethazine, and tylosin antibiotics.
Results/Conclusions
Cropped and prairie strip soils after manure addition supported similar rates of antibiotic degradation. Our initial data indicate that prairie soils have significantly different microbial communities relative to cropped soils. Non-metric multidimensional scaling (NMDS) of the soil bacterial 16S rRNA gene profiles of DNA from a continuous corn system and an adjacent, integrated prairie strip resulted in significant clusters, with increasing similarity of communities further into the strip or crop. Our study will evaluate the response of the prairie soil microbiomes to an introduced ecological disturbance caused by manure application. Outputs of this study will further extend the benefits that prairie strips can provide by evaluating their potential to mitigate the spread of antibiotics and ARGs in the environment.