Abstract Science‐based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) can improve water quality and reduce antimicrobial resistance genes (ARGs) from manured field runoff. Prior studies showed significant reductions in ARG abundances with prairie strips, but no enrichment was detected in surface soil layers, prompting further investigation into transport pathways. We hypothesized that ARGs may move vertically through strip soils. In an 8‐week soil column experiment, we characterized the vertical transport of manure‐amendment ARGs in prairie strip soils and leachate, comparing columns amended with anaerobically digested swine manure (ADM) and undigested swine manure (UDM) to a mineral‐based control (mineral solution amendment MIN). In amendment manures, the ARG concentrations in ADM and UDM were similar, and ADM had increased antibiotic residual concentrations. ADM and UDM amendments resulted in elevated ARG abundances in soil and leachate compared to MIN. After manure amendment, ARGs were transported up to 52.5 cm from the soil surface after rainfall events. Tetracycline resistance genes were persistently detected in amended subsurface soils, with tetM detectable until week 8 in both ADM and UDM amended soils, and tetO persisting to week 3 in ADM and week 8 in UDM amended soils. Generally, ADM amendments had lower ARG persistence than UDM, highlighting different transport dynamics depending on manure treatment. Most manure‐derived ARGs appeared to be retained or degraded within the strip soil profiles, with only 9.6 and 6.1 percent of UDM and ADM amendment ARGs recovered, respectively. Our results support that prairie strips can mitigate ARGs from manured field stormwater runoff and that ARGs are transported vertically through the soils and mostly retained at surface depths.
Carey et al. (Thu,) studied this question.