The Effects of Grazing Management on Water Quality Kirk Schwarte Iowa State University

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

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

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

Any stream or body of water that can not be used its designated use (drinking, recreation, fishing, aquatic life…etc.)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).Increased from 279 (2006) to 439 (2008). –40% of increase can be linked to change in standards StreamsStreams –Major causes are bacteria, invertebrates, and pollutant caused fish LakesLakes –Major causes are pH, algae, turbidity, and bacteria

/ Phosphorus Delivery to the Gulf of Mexico Interesting: 2009 Hypoxic zone 2009 Hypoxic zone shrank by half shrank by half Agriculture usually cited Agriculture usually cited as main source of water as main source of water nutrients nutrients Army Corps of Engineers project to make habitat for endangered Pallid SturgeonArmy Corps of Engineers project to make habitat for endangered Pallid Sturgeon 548 million tons of soil548 million tons of soil 358,403 lbs of P358,403 lbs of P 40-60,000 acres in 5ft of slurry40-60,000 acres in 5ft of slurry (Feedstuffs, 2010)

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

Sediment/Phosphorus Surface Runoff Lbs/acre Lbs/acre

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

Stream Bank Erosion

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

Pathogens E.coli 0157-H7E.coli 0157-H7 JuneAugustSeptember 20070%0%15.6% 20080%0%0% 20090%0%0%

Fecal Pathogens JuneAugustSeptember B. Coronavirus 0%0%1%0%0%0% B. Rotavirus 0%0%0%0%0%0% B. Enterovirus 1%39%29%19%41%13%

Runoff Pathogens AprilJuneAugustOctober E.Coli 0157:H B. Coronavirus B. Rotavirus B. Enterovirus

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

Management Practices Off-stream waterOff-stream water Rotational/Flash grazingRotational/Flash grazing Riparian BuffersRiparian Buffers Off-stream ShadeOff-stream Shade

Off-Stream Water WaterWater –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 grazingWater should located no greater than 800 ft. from the animals for efficient grazing Effects of off-stream water will differ based on weather conditionsEffects of off-stream water will differ based on weather conditions Pasture Management Guide, Iowa State University

Proportion of time spent within 110 ft zone when comparing the availability of an alternative water Source

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

CSU 11.9% CSR 8.2% 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) Temperature, C Estimated Probability P=

Rotational/Flash Grazing Brief grazing periods of highly erodible ground to utilize forage, but maintain bank integrity and water quality.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.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 a a a b b b 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.

Off-stream Shade Cattle seek shade during the hot summer daysCattle 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

Stream Bank Forage

Pasture Size and Shape Many pastures were developed on highly erodible land near streamsMany 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 goIf 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 sourceEven at cool temperatures, cattle will be found near the water source

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

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

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

Fencing ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf Two strand high tensile fence for rotational grazing and livestock exclusion $0.68/ft Four or more strands of barbed wire for rotational grazing and livestock exclusion $0.88/ft Fencing must be maintained for 10 years, property line fences are not covered.

Ponds Ponds constructed by making a dam, an embankment, or excavating to provide water to livestock only. $ $1.50/cub.yd. for construction $ $2.63 for repair 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

Prescribed Grazing To improve and maintain desired species, plant vigor, and plant quality to maintain a healthy herd, quality surface and subsurface water, reduce soil erosion, and improve soil conditions $40 - $80/acre A one time payment with a maximum of $50,000. Other grazing practices must be followed and documented before a payment is received. ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

Stream Crossings For the construction of a culvert/bridge type stream crossing for livestock and small equipment Typically a 50’ length x 24” diam. tube Rock- $22.25/cub.yd. Tube and Installation- $1,500 each Maintained for 10 years and landowner must get all construction permits ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

Well and Water Tank To drill a hole to form an aquifer -Non-potable water -6” or less diameter pipe - 20 years $13.00/ft A tank or water trough to provide water for animals -Can also cover the pump Varies… $0.38/gal ftp://ftp-fc.sc.egov.usda.gov/IA/Programs/FY09PracticeDescriptionsPaymentRates.pdf

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.

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 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.