Effect of Hillslope Position and Manure Application Rates on the Persistence of Fecal Source Tracking Indicators in an Agricultural Soil
- Gregory S. Piorkowskia,
- Greg S. Bezansonb,
- Rob C. Jamiesona,
- Lisbeth Truelstrup Hansena and
- Chris K. Yostc
- a Dep. of Process Engineering and Applied Science, Dalhousie Univ., 1360 Barrington Street, Halifax, NS, Canada, B3H 4R2
b Agriculture and Agri-Food Canada, Atlantic Food and Horticulture Research Centre, 32 Main Street, Kentville, NS, Canada, B4N 1J5
c Dep. of Biology, Univ. of Regina, LB 244, 3737 Wascana Parkway, Regina, SK, Canada, S4S 0A2
The influence of liquid dairy manure (LDM) application rates (12.5 and 25 kL ha−1) and soil type on the decay rates of library-independent fecal source tracking markers (host-associated Bacteroidales and mitochondrial DNA) and persistent (>58 d) Escherichia coli population structure was examined in a field study. The soils compared were an Aquic Haplorthod and a Typic Haplorthod in Nova Scotia, Canada, that differed according to landscape position and soil moisture regime. Soil type and LDM application rate did not influence Escherichia coli decay rates (0.045–0.057 d−1). Escherichia coli population structure, in terms of the occurrence of abundance of strain types, varied according to soil type (p = 0.012) but did not vary by LDM application rate (p = 0.121). Decay of ruminant-specific Bacteroidales (BacR), bovine-specific Bacteroidales (CowM2), and mitochondrial DNA (AcytB) markers was analyzed for 13 d after LDM application. The decay rates of BacR were greater under high-LDM application rates (0.281–0.358 d−1) versus low-LDM application rates (0.212–0.236 d−1) but were unaffected by soil type. No decay rates could be calculated for the CowM2 marker because it was undetectable within 6 d after manure application. Decay rates for AcytB were lower for the Aquic Haplorthod (0.088–0.100 d−1), with higher moisture status compared with the Typic Haplorthod (0.135 d−1). Further investigation into the decay of fecal source tracking indicators in agricultural field soils is warranted to assess the influence of soil type and agronomic practice on the differential decay of relevant markers and the likelihood of transport in runoff.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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