The use of antibiotics in animal agriculture has led to an increase in antibiotic resistance genes and resistant bacteria near areas of animal production and in animal manure. While animal manure is a valuable nutrient resource for agricultural production, it is also a potential vector for the transport of antibiotic resistance genes (ARGs) and bacteria (ARBs) and subsequently antibiotic resistance to the environment. To manage water quality in agricultural settings, prairie strips have been proposed as an effective conservation practice and have shown several benefits, including reducing nutrient loss, increasing ecosystem health, and improving biodiversity. We hypothesize that prairie strips as a field treatment can also attenuate the transport of ARGs and ARBs in surface runoff following rainfall events in manured agricultural fields. We performed two rainfall simulation experiments comparing the impacts of prairie strip installations on ARBs and ARGs associated with poultry or swine manure in soils and water. Soil and surface runoff were collected before and following manure application, as well as during a rain simulation event, resulting in 1,380 soil samples and 108 water samples from the two experiments. The bacterial community and over 300 ARGs were characterized in these samples by 16s sequencing and microfluidic qPCR.
Results/Conclusions
Our results identify distinct microbial communities unique to crop soils, prairie strip soils, and manure. These manure-associated bacteria were identified in soil receiving manure but were not found to be transported to adjacent prairie strip soils by surface runoff. Further, we observed reductions in ARG concentration in runoff water from plots with prairie strips compared to plots without prairie strips, despite significant concentrations of ARGs in the manure. For example, the concentration of the ARGs erm(F) and erm(B) were reduced by 99% in runoff water from plots with prairie strips compared to control plots with no prairie strips. We conclude that prairie strips attenuate the transport of ARGs and ARBs to the wider environment in agroecosystems. These findings add to the benefits associated with prairie strips used as a conservation practice.