Comparison of Selected Nutrients and Bacteria from Common Contiguous Soils Inside and Outside Swine Lagoon Effluent Spray Fields after Long-Term Use
- Michael R. McLaughlin *,
- John P. Brooks,
- Ardeshir Adeli and
- John J. Read
- USDA–ARS, Genetics and Precision Agriculture Research Unit, P.O. Box 5367, Mississippi State, MS 39762. Approved for publication as journal article number J-11698 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable. This work was prepared by employees of the U.S. Government as part of their official duties and is in the public domain and may be used without further permission. Assigned to Associate Editor A. Mark Ibekwe
Swine (Sus scrofa domestica) lagoon effluent is a valuable resource. In the U.S. Mid-South it is applied from April to September to fertilize grass hay in spray-irrigated fields. Lagoon levels of nutrients and bacteria, and soil levels of nutrients have been documented, but little was known of effluent bacterial levels in soil. The present study examined levels of selected effluent bacteria and nutrients in soils inside and outside spray fields after >15 yr of effluent irrigation. Samples were collected February to March 2009 from contiguous soils spanning adjacent irrigated and nonirrigated areas. Separate soil cores for bacterial and nutrient tests were collected in pairs <10 cm apart. Five cores each were collected at 15-m intervals and combined, respectively, to comprise inside and outside samples from each of 20 soils (four each from five farms/spray fields). Analyses of data combined across all soils showed higher pH and Mehlich-3-extractable (M3-) P, Mg, K, Na, Cu, and Zn inside than outside spray fields, while total N, total C, M3-Ca, and M3-Mn did not differ. Bacterial levels were higher inside than outside spray fields for heterotrophic plate counts, thermotolerant coliforms, Staphylococcus spp., and Clostridium perfringens, but levels of Escherichia coli and Enterococcus spp. were not different. Cultural presence/absence tests for three pathogens (Listeria spp., Campylobacter spp., and Salmonella spp.) detected only Listeria spp., which did not differ inside (23% positive samples) and outside (28% positive). Molecular tests detected all three pathogens at low levels that were not different inside and outside. We found no evidence of cumulative buildup of Campylobacter spp., Listeria spp., or Salmonella spp. in spray field soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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