Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2012
Publication Date: 1/4/2013
Citation: Unger, I.M., Goyne, K.W., Kennedy, A.C., Kremer, R.J., McLain, J.E., Williams, C.F. 2013. Antibiotic effects on microbial community characteristics in soils under conservation management practices. Soil Science Society of America Journal. 77:100–112. Interpretive Summary: Land application is a cost-effective method to dispose of animal manure. Vegetative filter strips may prevent runoff containing these antibiotics from manure-amended fields into surface waters during and after rainfall or irrigation. The antibiotics in runoff water entering the filter strips may adversely affect soil microbial populations and interfere with a diverse biological activity in the root zone necessary to provide long-term treatment. We examined potential differences in soil microbial community characteristics with the addition of two antibiotics. Shifts in microbial community structure and increased antibiotic resistance were not observed, suggesting that the soil microbial communities were robust and buffered the effects of the antibiotics. These results are important to farmers, soil scientists, soil conservation professionals, and extension personnel because the information provides guidance in proper management and application of livestock manures with minimum impact on soil, air and water quality.
Technical Abstract: Veterinary antibiotics (VAs) administered to livestock are introduced to agroecosystems via land application of manure, posing a potential human and environmental health risk. These Antibiotics may adversely affect soil microbial communities. The objectives of this research were to investigate potential changes in microbial community structure and function and to quantify the development of antibiotic resistance in vegetative filter strips and no-till soils exposed to various VA classes and concentrations. Laboratory mesocosms were established using soils collected from no-till cropland and two VFS (grass and agroforestry). Soils were treated with oxytetracycline or lincomycin (5–200 mg/kg soil). Individual mesocosms underwent destructive sampling at nine time points during 63 d, and the soils were tested for soil microbial function (C-utilization, dehydrogenase, and fluorescein diacetate hydrolysis assays), community structure (phospholipid fatty acid analysis), and antibiotic resistance. Functional assays associated with all VA treatments showed an initial inhibitory effect, but this trend was generally reversed by the seventh day. Shifts in microbial community structure and increased antibiotic resistance were not observed, suggesting that the soil microbial communities were robust to the effects of oxytetracycline and lincomycin at test concentrations. This work indicates that using filter strips to mitigate VA loss from agroecosystems will not diminish important primary functions associated with the use of these strips in agriculture.