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This article in JEQ

  1. Vol. 40 No. 4, p. 1303-1313
     
    Received: Dec 8, 2010
    Published: July, 2011


    * Corresponding author(s): jrussell@iastate.edu
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doi:10.2134/jeq2010.0524

Grazing Management Effects on Sediment, Phosphorus, and Pathogen Loading of Streams in Cool-Season Grass Pastures

  1. Kirk A. Schwartea,
  2. James R. Russell *a,
  3. John L. Kovarb,
  4. Daniel G. Morricalc,
  5. Steven M. Ensleyd,
  6. Kyoung-Jin Yoond,
  7. Nancy A. Cornicke and
  8. Yong Il Choe
  1. a Dep. of Animal Science, Iowa State Univ., Ames, IA 50011
    b USDA–ARS, National Lab. for Agriculture and the Environment, Ames, IA 50011
    c Dep. of Animal Science, Mention of a proprietary product does not constitute a guarantee or warranty of the product by Iowa State University, USDA-ARS, or the authors and does not imply its approval to the exclusion of other products that also may be suitable. Assigned to Associate Editor Ed Topp
    d Dep. of Vet. Diagnostics and Production Animal Med., Mention of a proprietary product does not constitute a guarantee or warranty of the product by Iowa State University, USDA-ARS, or the authors and does not imply its approval to the exclusion of other products that also may be suitable. Assigned to Associate Editor Ed Topp
    e Dep. of Vet. Microbiology and Preventative Med., Iowa State Univ., Ames, IA 50011. Mention of a proprietary product does not constitute a guarantee or warranty of the product by Iowa State University, USDA-ARS, or the authors and does not imply its approval to the exclusion of other products that also may be suitable. Assigned to Associate Editor Ed Topp

Abstract

Erosion and runoff from pastures may lead to degradation of surface water. A 2-yr grazing study was conducted to quantify the effects of grazing management on sediment, phosphorus (P), and pathogen loading of streams in cool-season grass pastures. Six adjoining 12.1-ha pastures bisected by a stream in central Iowa were divided into three treatments: continuous stocking with unrestricted stream access (CSU), continuous stocking with restricted stream access (CSR), and rotational stocking (RS). Rainfall simulations on stream banks resulted in greater (P < 0.10) proportions of applied precipitation and amounts of sediment and P transported in runoff from bare sites than from vegetated sites across grazing treatments. Similar differences were observed comparing vegetated sites in CSU and RS pastures with vegetated sites in CSR pastures. Bovine enterovirus was shed by an average of 24.3% of cows during the study period and was collected in the runoff of 8.3 and 16.7% of runoff simulations on bare sites in CSU pastures in June and October of 2008, respectively, and from 8.3% of runoff simulations on vegetated sites in CSU pastures in April 2009. Fecal pathogens (bovine coronavirus [BCV], bovine rotavirus group A, and Escherichia coli O157:H7) shed or detected in runoff were almost nonexistent; only BCV was detected in feces of one cow in August of 2008. Erosion of cut-banks was the greatest contributor of sediment and P loading to the stream; contributions from surface runoff and grazing animals were considerably less and were minimized by grazing management practices that reduced congregation of cattle by pasture streams.

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