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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #341099
Title: Impacts of swine manure application and land management on microbial communities and resistance genes in soils and drainage waters

Author
item HOWE, ADINA - Iowa State University
item YANG, FAN - Iowa State University
item LUBY, ELIZABETH - Iowa State University
item Moorman, Thomas
item SOUPIR, MICHELLE - Iowa State University

Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Administration of in-feed antibiotics have been observed to lead to increased concentrations of antibiotics and antibiotic resistant bacteria in swine manure. Since swine manure is often used as a fertilizer in agriculture, there is concern that antibiotics and resistance genes introduced into the agroecosystem promote the spread of microbial antibiotic resistance genes in agricultural drainage water. We simulated an agroecosystem with drainage using soil columns. Soils were collected from a research farm in Nashua, IA, which employs corn and soybean rotation with fertilizer (manure or urea ammonium nitrate) prior to the corn growing season. The fields were managed with either chisel plow or no-till practices. To simulate the field practices, manure was applied to a subset of columns (no-till and chisel plow with no-manure and manure history) and six simulated rainfall events (up to 106 days). Soil column drainage water was captured, filtered, and DNA was extracted. After every other rainfall event, subsets of manured and non-manured soil columns were destructively sampled and soil DNA was extracted from the top and bottom of the columns. Simulated manure applications significantly changed microbial distributions in soils and drainage water. Tillage, manure-use histories, and sample location in the soil column also contributed to the observed microbial community variations. Manure-associated communities were significantly more abundant in soil than drainage waters. Further, manure-derived community members were present, but decreased with time in both drainage water and top soil column while they persisted in the bottom of the column. We selected species with known resistance genes (erm and tet) and observed similar patterns of over time and between manure-applied and control columns, suggesting that resistant genes also attenuate over time. These resistant genes are being targeted for qPCR assays to confirm our observations. The results in this study inform our understanding of how to manage and mitigate antibiotics and their agricultural inputs. Our results will help to identify potential targets for tracking the impacts of manure and its associated microbial communities and antibiotic resistant genes in agricultural settings.