Fate and transport of antibiotics and antibiotic resistance genes in runoff and soil as affected by timing of swine slurry application

Authors: BARRIOS, RENYS - University Of Nebraska; BARTELT-HUNT, SHANNON - University Of Nebraska; Gilley, John; SCHMIDT, AMY - University Of Nebraska; SNOW, DANIEL - University Of Nebraska; LI, XU - University Of Nebraska

Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2020
Publication Date: 1/7/2020
Citation: Barrios, R.E., Bartelt-Hunt, S.L., Gilley, J.E., Schmidt, A.M., Snow, D.D., Li, X. 2020. Fate and transport of antibiotics and antibiotic resistance genes in runoff and soil as affected by timing of swine slurry application. Environmental Pollution. 712(10):136505. https://doi.org/10.1016/j.scitotenv.2020.136505.
DOI: https://doi.org/10.1016/j.scitotenv.2020.136505

Interpretive Summary: Land application of swine slurry is a common practice to supplement nutrients in soil used for crop production. However, antibiotic residues and antibiotic resistance genes (ARGs) may be released into the environment during land application. Field testing is critical in identifying manure management practices effective in minimizing the environmental impacts of manure-borne antibiotics and ARGs. The objective of this study was to determine how the timing of swine slurry application relative to rainfall events impacts the fate and transport of antibiotics and ARGs in surface runoff and slurry-amended soil. Swine slurry was either broadcast or injected on field test plots. A series of three 30-min simulated rainfall events, 24 hours apart, were initiated on manured plots 1 day, 1 week, 2 weeks, or 3 weeks after slurry application. Results showed that an interval greater than 2 weeks between slurry application and rainfall often significantly reduced the levels of antibiotics and ARGs tested in runoff. For soil samples from broadcast plots, concentrations of two of the three antibiotics tested decreased substantially in the first two weeks after slurry application. In contrast, concentrations of most of the ARGs tested in soil did not change significantly during the test period. Information obtained from the study can be beneficial in designing manure management practices and estimating the environmental loading of antibiotics and ARGs resulting from swine slurry application.

Technical Abstract: Land application of swine slurry is a common practice to supplement nutrients in soil used for crop production. However, antibiotic residues and antibiotic resistance genes (ARGs) may be released into the environment during land application. Field testing is critical in identifying manure management practices effective in minimizing the environmental impacts of manure-borne antibiotics and ARGs. The objective of this study was to determine how the timing of swine slurry application relative to rainfall events impacts the fate and transport of antibiotics and ARGs in surface runoff and slurry-amended soil. Swine slurry was either broadcast or injected on field test plots. A series of three 30-min simulated rainfall events, 24 hours apart, were initiated on manured plots 1 day, 1 week, 2 weeks, or 3 weeks after slurry application. Results showed that an interval greater than 2 weeks between slurry application and rainfall often significantly reduced the levels of antibiotics and ARGs tested in runoff with the exception of tet(X). For soil samples from broadcast plots, concentrations of two of the three antibiotics tested (lincomycin and tiamulin) decreased substantially in the first two weeks after slurry application. In contrast, concentrations of most of the ARGs tested (tet(Q), tet(X), and erm(A)) in soil did not change significantly during the test period. Information obtained from the study can be beneficial in designing manure management practices and estimating the environmental loading of antibiotics and ARGs resulting from swine slurry application.