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IMPAIRMENTS TO IOWA’S WATER RESOURCES 2008 Impaired Waters List (357 streams & 77 lakes)

Management Strategies to Minimize the Impacts of Grazing on Non-point Source Pollution of Pasture Streams in the Midwest J.R. Russell 1 , D.A. Bear 1 , K.A. Schwarte 1 , and M. Haan 2 1 Iowa State University, Ames, IA 2 Michigan State University, Hickory Corners, MI.

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IMPAIRMENTS TO IOWA’S WATER RESOURCES 2008 Impaired Waters List (357 streams & 77 lakes)

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  1. Management Strategies to Minimize the Impacts of Grazing on Non-point Source Pollution of Pasture Streams in the MidwestJ.R. Russell1, D.A. Bear1, K.A. Schwarte1, and M. Haan21Iowa State University, Ames, IA2Michigan State University, Hickory Corners, MI

  2. IMPAIRMENTS TO IOWA’S WATER RESOURCES2008 Impaired Waters List (357 streams & 77 lakes) (Iowa DNR, 2008)

  3. PHOSPHORUS DELIVERY TO THE GULF OF MEXICO (Alexander et al., 2008) http://water.usgs.gov/nawqa/sparrow/gulf_findings/

  4. HYPOTHETICAL ROUTES OF NONPOINT SOURCE POLLUTION BY GRAZING CATTLE Direct manure deposition Stream bank erosion Surface run-off

  5. FACTORS CONTROLLING THE EFFECTS OF GRAZING ON WATER QUALITY • Location of grazing • Timing of grazing • Intensity of grazing • Length of grazing (CAST, 2002)

  6. MODEL FOR QUANTIFYING THE EFFECTS OF GRAZING MANAGEMENT ON NONPOINT SOURCE POLLUTION OF PASTURE STREAMS Grazing Days Stream Length Cattle #s Diet intake and indigestibility Cow-days/ft Pollutant concentration or frequency Climate Off-stream water Fecal Pollutant Load or Incidence Grazing management Distribution Riparian zone Stream Plant species Shade distribution Congregation area Open area Transport in runoff Transport in runoff Stream

  7. EFFECTS OF PASTURE SIZE ON THE CONGREGATION OF GRAZING COWS IN AND WITHIN 100 ft OF A PASTURE STREAM OR POND ON SIX PASTURES OVER THREE YEARS y = 35.4 - 0.83x + 0.005x2 (r2 =0.61)

  8. IMPLICATIONS OF PASTURE SIZE AND SHAPE ON CATTLE TEMPORAL/SPATIAL DISTRIBUTIONRESEARCH

  9. PERCENTAGE OF TIME GRAZING CATTLE ARE IN AND WITHIN 110 ft OF A PASTURE STREAM IN TWO YEARS30 ac pastures463 ft stream reach (Haan et al., 2010) CSU = Continuous stocking unrestricted

  10. EFFECT OF RESTRICTING STREAM ACCESS TO STABILIZED CROSSING ON CONGREGATION OF CATTLE IN OR NEAR PASTURE STREAMS IN TWO YEARS (Haan et al., 2010) CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted

  11. EFFECT OF RESTRICTING STREAM ACCESS BY ROTATIONAL GRAZING ON CATTLE CONGREGATION IN OR NEAR PASTURE STREAMS IN TWO YEARS (Haan et al., 2010) CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  12. EFFECT OF SHORT-TERM ACCESS TO OFFSTREAM WATER AND MINERAL SUPPLEMENTATION ON CONGREGATION OF CATTLE IN OR NEAR PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted w/W or open = with offstream water and mineral

  13. EFFECT OF OFF-STREAM WATER OR RESTRICTED STREAM ACCESS ON CONGREGATION OF CATTLE WITHIN 110 FT OF A PASTURE STREAM IN 10 (small) OR 30 (large) ACRE PASTURES OVER 5 MONTHS (2010)

  14. IMPLICATIONS OF PASTURE SIZE AND SHAPE ON CATTLE TEMPORAL/SPATIAL DISTRIBUTIONRegulatory • Treatments to control NPS of pasture streams • seem likely to be most effective on small or • narrow pastures.

  15. Probability of cattle presence within 110 feet of a pasture stream over the temperature range

  16. EFFECT OF THE TEMPERATURE-HUMIDITY INDEX ON THE AMOUNTS OF TIME CATTLE WERE IN THE RIPARIAN AREAS OF BERMUDAGRASS-TALL FESCUE PASTURES WITH OR WITHOUT OFFSTREAM WATER (Franklin et al. 2009)

  17. EFFECTS OF AMBIENT TEMPERATURE ON THE PROBABILITY OF COWS SEEKING SHADE

  18. Percent of the total time cattle spent within the stream zone by interval

  19. Distribution of pasture shade • Cattle in pastures with more shade within the stream zone spent more time in the stream zone

  20. EFFECTS OF GRAZING MANAGEMENT ON NONPOINT SOURCE POLLUTION OF PASTURE STREAMS

  21. EFFECTS OF GRAZING MANAGEMENT ON ANNUAL EROSION/DEPOSITION ACTIVITY AND NET EROSION OF STREAM BANKS IN 2008 AND 2009

  22. EFFECTS OF STOCKING RATE BETWEEN BIMONTHLY MEASUREMENTS OF THE PROPORTION OF BARE AND MANURE-COVERED GROUND WITHIN 50 FT OF STREAMS IN 13 PASTURES y = 10.4 + 3.73x – 0.314x2 (r2 =0.16) y = 0.1 + 0.18x – 0.009x2 (r2 =0.35)

  23. GRAZING SYSTEM EFFECTS ON PROPORTIONS OF BARE AND MANURE-COVERED GROUND WITHIN 15 TO 110 FT OF PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  24. GRAZING SYSTEM EFFECTS ON PROPORTIONS OF APPLIED PRECIPITATION AND AMOUNTS OF SEDIMENT AND P TRANSPORTED IN RUNOFF FROM SIMULATED RAIN APPLIED TO BARE AND VEGETATED SITES ON STREAMBANKS AT 7.5 cm/hr (P < 0.10) a a b b c a a a a b b b c b c

  25. CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO ANNUAL SEDIMENT LOADING OF PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  26. CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO ANNUAL SEDIMENT LOADING OF PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  27. CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO ANNUAL PHOSPHORUS LOADING OF PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  28. CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO ANNUAL PHOSPHORUS LOADING OF PASTURE STREAMS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  29. GRAZING SYSTEMS EFFECTS ON STREAM BANK EROSION SUSCEPTIBILITY (1 – 60) AND VEGETATION (1 – 4) SCORES OVER FIVE YEARS CSU = Continuous stocking unrestricted CSR = Continuous stocking restricted RS = Rotational stocking

  30. ROLE OF GRAZING CATTLE ON PATHOGEN LOADING OF PASTURE STREAMS

  31. STOCKING RATE EFFECTS ON MEAN CONCENTRATIONS OF TOTAL COLIFORMS IN BIWEEKLY WATER SAMPLES FROM UP- AND DOWNSTREAM SAMPLING SITES IN 13 PASTURES OVER 3 YEARS

  32. STOCKING RATE EFFECTS ON THE INCIDENCES OF BOVINE ENTEROVIRUS (BEV), CORONAVIRUS (BCV), AND ROTAVIRUS (BRV) IN BIWEEKLY WATER SAMPLES FROM STREAMS IN 13 PASTURES FOR THREE YEARS BEV: y = 1.98+0.017x-0.00089x2 (r2=0.0101) BCV: y = 2.54+0.41x-0.015x2 (r2=0.0345) BRV: y = 0.27+0.11x-0.0020x2 (r2=0.0708)

  33. EFFECTS OF PRESENCE OR ABSENCE OF CATTLE IN PASTURES FOR 0 TO 6 DAYS PRIOR TO SAMPLING ON THE INCIDENCES OF BOVINE ENTEROVIRUS, CORONAVIRUS, AND ROTAVIRUS IN UP- OR DOWNSTREAM WATER SAMPLES FROM 13 PASTURES FOR 3 YEARS

  34. INCIDENCE OF BOVINE ENTEROVIRUS AND CORONAVIRUS SHED BY 90 GRAZING COWS IN 3 MONTHS OVER TWO YEARS(No E. coli O157:H7 or Bovine rotavirus shed)

  35. INCIDENCE OF BOVINE ENTEROVIRUS IN RUNOFF FROM RAINFALL SIMULATIONS ON STREAM BANKS OF PASTURES WITH UNRESTRICTED STREAM ACCESS IN TWO YEARS(No E. coli O157:H7, Bovine coronavirus, or Bovine rotavirus observed)

  36. CONCLUSIONS • Stream bank erosion is primarily related to hydrologic processes that supersede possible grazing effects • Improper grazing management may increase: • Bare ground near pasture streams • Manure concentration near pasture streams • Sediment and nutrient loading of precipitation runoff • Pathogen loading of pasture streams by grazing cattle is: • Poorly related to presence of total coliforms • Bovine enterovirus may be a better indicator • Confounded by upstream loading • Domestic and wildlife species • Rare and controlled by: • Seasonal incidence of shedding of the pathogens • Manure distribution • Transport of the pathogens to the stream

  37. CONCLUSIONS • Risks of grazing on nonpoint source pollution of pasture streams may be controlled by maintaining streamside vegetation by use of: • Stabilized crossings with riparian buffers • Rotational grazing • Off-stream shade? • Off-stream water and/or nutrient supplementation???

  38. CONCLUSIONS • The Best Management Practices to control nonpoint source pollution on individual pastures will be site specific. • Small, narrow pastures will likely need more restrictive practices to control distribution of grazing cattle than large, wide pastures • Other characteristics to consider • Cattle stocking rate • Cattle breed, age, and physiological state • Distance to off-stream water • Shade distribution • Botanical composition • Stream order and evolution

  39. Acknowledgements: • This project is supported in part by: • The Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Award No. 2006-51130-03700 • The Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Award No. 2007-35102-18115 • The Leopold Center for Sustainable Agriculture • Iowa Beef Center • Rathbun Land and Water Alliance

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