The effects of grazing management on water quality
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The Effects of Grazing Management on Water Quality. Kirk Schwarte Iowa State University [email protected] Materials and Methods. Six, 30 acre, cool season grass pastures Two blocks, three treatments Continuous stocking with unrestricted stream access (CSU)

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Materials and methods
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







Effects of poorly managed grazing
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

Non point source pollution
Non-Point Source Pollution








Aquatic Plants

Water Quality

Water Clarity

Die / Decompose


Impaired Waters

Aquatic Life

Hypoxia / Eutrophication

Impaired waters
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

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)

Surface runoff
Surface Runoff

Slopes ranged from 3.4° to 33°, with the average of 13°



Stream bank erosion
Stream Bank Erosion

  • Majority of erosion caused by the hydrology of the stream, not cattle

    • Cut banks and Oxbows

  • Freeze/thaw during winter months

Incidence of pathogens in grazing beef cattle
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)


  • E.coli 0157-H7

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

Management practices
Management Practices

  • Off-stream water

  • Rotational/Flash grazing

  • Riparian Buffers

  • Off-stream Shade

Off stream water
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

Riparian buffers
Riparian Buffers

  • Complete exclusion from riparian areas

  • Requires off-site water or stream crossing

  • Eligible for government payments?

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)


P= 0.0663

Estimated Probability

CSU 11.9%

CSR 8.2%


Temperature, C

Rotational flash grazing
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

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 = 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.

Off stream shade
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

Pasture size and shape
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

Pasture size and shape1
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+++

Environmental quality incentives program eqip
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…


Fencing must be maintained for 10 years, property line fences are not covered.


Must be maintained for 20 years and built to store 35 years worth of sediment

Prescribed grazing
Prescribed Grazing

Other grazing practices must be followed and documented before a payment is received.

Stream crossings
Stream Crossings

Maintained for 10 years and landowner must get all construction permits

Well and water tank
Well and Water Tank


  • 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.


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.