The Effects of Grazing Management on Water Quality

1. The Effects of Grazing Management on Water Quality Kirk Schwarte Iowa State University kirksch@iastate.edu

2. Materials and Methods • Six, 30 acre, cool season grass pastures • Two blocks, three treatments • Continuous stocking with unrestricted stream access (CSU) • Continuous stocking with restricted stream access (CSR) • Rotational stocking (RS) • Bisected by a 463 ft reach of stream that flows year round CSR CSU CSR RS RS CSU

3. Effects of Poorly Managed Grazing • Cattle congregate near water sources • Disturb banks • Shear force from hooves break down bank structure • Increases surface runoff • Increases soil bulk density • Promotes sediment, phosphorus, and pathogen loading • Decrease streamside vegetation • Decreases stream shade • Increases stream width to depth ratio • Decreases ‘erosion resistance’ by plants

4. Non-Point Source Pollution Runoff Phosphorus Bacteria Pathogens Sediment Nitrogen Algae Aquatic Plants Water Quality Water Clarity Die / Decompose Oxygen Impaired Waters Aquatic Life Hypoxia / Eutrophication

5. Impaired Waters • Any stream or body of water that can not be used its designated use (drinking, recreation, fishing, aquatic life…etc.) • Increased from 279 (2006) to 439 (2008). • 40% of increase can be linked to change in standards • Streams • Major causes are bacteria, invertebrates, and pollutant caused fish • Lakes • Major causes are pH, algae, turbidity, and bacteria http://www.igsb.uiowa.edu/wqm/wqa/303d/2008/2008FinalListFactSheet.pdf

6. Phosphorus Delivery to the Gulf of Mexico • Interesting: • 2009 Hypoxic zone • shrank by half • Agriculture usually cited • as main source of water • nutrients • Army Corps of Engineers project to make habitat for endangered Pallid Sturgeon • 548 million tons of soil • 358,403 lbs of P • 40-60,000 acres in 5ft of slurry • (Feedstuffs, 2010) http://water.usgs.gov/nawqa/sparrow/gulf_findings/

7. Surface Runoff Slopes ranged from 3.4° to 33°, with the average of 13° % cm

8. Sediment/Phosphorus Surface Runoff Lbs/acre Lbs/acre

9. Stream Bank Erosion • Majority of erosion caused by the hydrology of the stream, not cattle • Cut banks and Oxbows • Freeze/thaw during winter months

10. Stream Bank Erosion

11. Incidence of Pathogens in Grazing Beef Cattle • Likelihood of pathogens in the GI tract of cattle is high • Shedding is highly variable • Believed to be dependent on stress (calving / heat)

12. Pathogens • E.coli 0157-H7

13. Fecal Pathogens

14. Runoff Pathogens

15. Mean Concentrations of Fecal Coliforms in Upstream and Downstream Samples from Pastures in the Lake Rathbun Watershed

16. Management Practices • Off-stream water • Rotational/Flash grazing • Riparian Buffers • Off-stream Shade

17. Off-Stream Water • Water • 8-12 gal. for maintenance • 20-25 gal. during hot weather • Lactating > Dry Cows • Water should located no greater than 800 ft. from the animals for efficient grazing • Effects of off-stream water will differ based on weather conditions Pasture Management Guide, Iowa State University

19. Riparian Buffers • Complete exclusion from riparian areas • Requires off-site water or stream crossing • Eligible for government payments?

20. Probability of cattle being within the streamside zone in pastures with continuous stocking with unrestricted stream access (CSU), continuous stocking with restricted stream access (CSR) 0.30 P= 0.0663 Estimated Probability CSU 11.9% CSR 8.2% 0.00 Temperature, C

21. Rotational/Flash Grazing • Brief grazing periods of highly erodible ground to utilize forage, but maintain bank integrity and water quality. • Spring grazing • Late summer grazing • Managed to maintain sufficient forage height (4 inches) in riparian areas. • Minimize surface runoff • Maintain plant density

22. Mean proportions of time that cattle spent within the 110 ft zone of pastures with continuous stocking with unrestricted stream access (CSU), continuous stocking with restricted stream access (CSR), or rotational stocking (RS) during the 2008 grazing season. a b a b a b a b a = differences between CSU and CSR b = differences between CSU and RS (P < 0.10) *RS riparian paddock was stocked for a total of 6 days throughout the grazing season, or 4.3% of time from mid May through September.

23. Off-stream Shade • Cattle seek shade during the hot summer days • Allows for a place for cattle to congregate and rest away from water sources • May ease pressure on grasses near the stream from high foot traffic

24. Stream Bank Forage

25. Pasture Size and Shape • Many pastures were developed on highly erodible land near streams • If the pasture has a large percentage of the pasture in a riparian area, cattle don’t have anywhere else to go • Even at cool temperatures, cattle will be found near the water source

26. Pasture Size and Shape % of Pasture in Riparian Area Farm A- 24.3 Farm B- 2.5 Farm C-17.2 Farm D-22.2 Farm E- 28.7 Farm A1+++ Farm B1+++ Farm C1+++ Farm D1+++ Farm E1+++ Farm A2+++ Farm B2+++ Farm C2+++ Farm D2+++ Farm E2+++

27. Treatments to control NPS of pasture streams • seem likely to be most effective on small or • narrow pastures.

28. Environmental Quality Incentives Program (EQIP) • Provides support to landowners to implement programs that will benefit the conservation of our nature resources • Provides assistance in building fences, wells and water sources, stream crossings, grass seeding, and more…

29. Fencing Fencing must be maintained for 10 years, property line fences are not covered. ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

30. Ponds Must be maintained for 20 years and built to store 35 years worth of sediment ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

31. Prescribed Grazing Other grazing practices must be followed and documented before a payment is received. ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

32. Stream Crossings Maintained for 10 years and landowner must get all construction permits ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

33. Well and Water Tank ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

34. IMPLICATIONS • Stream bank erosion seems primarily related to stream hydrology. • Coliform and pathogen loading of pasture streams comes from numerous sources including wildlife and humans. • Improper grazing management may increase: • Bare ground near pasture streams • Manure concentration near pasture streams • Sediment and nutrient loading of precipitation runoff • Risks of grazing on pasture streams may be controlled by: • Stabilized crossings with riparian buffers • Rotational grazing • Off-stream water • Greatest risk of NPS pollution from grazing occurs in small and/or narrow pastures.

35. Questions? This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Award No. 2006-51130-03700. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.