ENVIRONMENTALLY SOUND MANURE MANAGEMENT FOR REDUCTION OF GAS EMISSIONS, NUTRIENTS, AND PATHOGENS
Location: Agroecosystem Management Research
Title: Microbiological quality of runoff from manure-amended fields as affected by perennial grass buffer strip
Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2011
Publication Date: May 21, 2011
Citation: Durso, L.M., Gilley, J.E., Woodbury, B.L., Marx, D.B. 2011. Microbiological quality of runoff from manure-amended fields as affected by perennial grass buffer strip. American Society for Microbiology 111th General Meeting, New Orleans, Louisiana. 2011 CDROM: ASM Abstracts. Poster Board No. 2803.
Background: Runoff from manure-amended agricultural fields can provide a transmission route for pathogens and fecal indicator organisms to surface waters. Establishment of stiff-stemmed perennial grass hedges along the contours of agricultural fields has been shown to reduce both soil and nutrient loss. This study tests the hypothesis that narrow switch grass hedges could also reduce runoff of fecal microorganisms (bacteria and viruses) immediately following manure application.
Methods: Rainfall simulation experiments were performed on 24 field plots (0.75 m x 4 m) of silty clay loam soil, half of which had a 1.4 m switch grass hedge established at the base. Beef cattle manure was applied to meet 0, 1, 2, or 4-year corn P requirements. Three 30 minute simulated rainfall events were applied at an intensity of 70 mm hr-1on each of three days. Runoff was analyzed for total coliforms, generic Escherichia coli, Enterococcus, E. coli O157:H7, and E. coli somatic phage using standard methods. Presence or absence of a grass hedge was the main plot treatment and manure application rate was the subplot treatment.
Results: A significant difference (P<0.01) in total coliform counts for hedge (5.4 cfu ha-1) vs no-hedge plots (4.9 cfu ha-1) was observed. The test for total coliforms includes both fecal and plant derived bacteria, and the higher total coliform counts in the hedge treatments can be attributed to plant-based contributions. No significant differences were noted for E. coli or Enterococcus, both fecal-indicator organisms, however E. coli somatic phage counts were lower (P<0.01) for the hedge (1.59 pfu ha-1) vs no-hedge (2.68 pfu ha-1) plots.
Conclusions: Fecal indicator bacteria and phages display different transport characteristics in runoff from manure-amended fields. Narrow switch-grass hedges did not reduce the number of fecal indicator bacteria transported in runoff shortly after manure application however they are effective at reducing the transport of somatic phage, a viral indicator of fecal contamination.