Management Strategies to Minimize the Impacts of Grazing on Non-point Source Pollution of Pasture Streams in the Midwest

J.R. Russell1, D.A. Bear1, K.A. Schwarte1, and M. Haan21Iowa State University, Ames, IA

2Michigan State University, Hickory Corners, MI

IMPAIRMENTS TO IOWA’S WATER RESOURCES2008 Impaired Waters List (357 streams & 77 lakes)

pHAlga

e

Turbid

ity

Bacter

ia

Siltatio

n

Nutrien

ts

Fish ki

lls

Mercu

ry

Low D

OPCBs

Nuisan

ce al

gae

Habita

t alte

ratio

ns0

10

20

30

40

50

60

Num

ber o

f im

paire

d la

kes

(Iowa DNR, 2008)

PHOSPHORUS DELIVERY TO THE GULF OF MEXICO (Alexander et al., 2008)

http://water.usgs.gov/nawqa/sparrow/gulf_findings/

HYPOTHETICAL ROUTES OF NONPOINT SOURCE POLLUTION BY GRAZING CATTLE

Direct manure deposition Stream bank erosion or is it cut bank erosion?

Surface run-off

FACTORS CONTROLLING THE EFFECTS OF GRAZING ON WATER QUALITY

• Location of grazing• Timing of grazing• Intensity of grazing• Length of grazing

(CAST, 2002)

EFFECTS OF COW DISTRIBUTION ON DISTRIBUTION OF FECES AND URINE IN

PASTURES

MODEL FOR QUANTIFYING THE EFFECTS OF GRAZING MANAGEMENT ON NONPOINT SOURCE

POLLUTION OF PASTURE STREAMS

Pollutant concentration or frequency

Cattle #s Grazing Days Stream Length

Cow-days/ftDiet intake and indigestibility

Fecal Pollutant Load or Incidence

DistributionGrazing management

Plant speciesShade distribution

Stream Riparian zone

Open area Congregation area

Transport inrunoff

Transport in runoff

Stream

ClimateOff-stream water

EFFECTS OF AMBIENT TEMPERATURE ON THE PROBABILITY OF GRAZING COWS BEING IN AND WITHIN

100 ft OF A STREAM OR POND IN PASTURES ON FIVE FARMS OVER THREE YEARS

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

-10 -5 0 5 10 15 20 25 30 35 40

Temperature (C)

Prob

abili

ty, %

Farm A

Farm B

Farm C

Farm D

Farm E

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

0.0

10.0

20.0

30.0

40.0

50.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0

Total Pasture Size, ha

GPS

Rea

ding

s w

ithin

the

Wat

ersi

de Z

ones

,%

of T

otal

GPS

Rea

ding

s

y = 35.4 - 0.83x + 0.005x2 (r2 =0.61)

IMPLICATIONS OF PASTURE SIZE AND SHAPE ON CATTLE TEMPORAL/SPATIAL DISTRIBUTION

RESEARCHRef. (State) Approx.

pasture size, ac

Treatment Est. distance from

treatment to stream, ft

Stream and/or

riparian effects

Sheffield et al., 1997 (VA)

35 - 54 Offstream water

37 Reduced congregation

Porath et al., 2002 (OR)

30 Offstream water

1600 Reduced congregation

Byers et al., 2005 (GA)

42 Offstream water

296 Reduced congregation

“ 35 Offstream water

263 No significant effect on

congregationAgouridis et

al., 2005 (KY)5 – 7.5 Offstream

water230 No effect on

congregation

Line et al., 2000 (NC)

104 Offstream water

338 No effect on NPS

IMPLICATIONS OF PASTURE SIZE AND SHAPE ON CATTLE TEMPORAL/SPATIAL DISTRIBUTION

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

PERCENTAGE OF TIME GRAZING CATTLE ARE IN

AND WITHIN 110 ft OF A PASTURE

STREAM IN TWO YEARS

30 ac pastures463 ft stream reach

(Haan et al., 2010)

May June July Aug Sept Avg0

0.51

1.52

2.53 2006-07

CSU

Month

% o

f obs

erva

tions

in

stre

amMay June July Aug Sept Avg

02468

10121416 2006-07

CSU

Month

% o

f obs

erva

tions

w

ithin

33

m o

f a

stre

am

CSU = Continuous stocking unrestricted

EFFECT OF RESTRICTING

STREAM ACCESS TO STABILIZED

CROSSING ON CONGREGATION OF CATTLE IN OR NEAR PASTURE STREAMS

IN TWO YEARS(Haan et al., 2010)

May June July Aug Sept Avg0

0.51

1.52

2.53 2006-07

CSUCSR

Month

% o

f obs

erva

tions

in

stre

amMay June July Aug Sept Avg

02468

10121416 2006-07

CSUCSR

Month

% o

f obs

erva

tions

w

ithin

33

m o

f a

stre

am

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restricted

EFFECT OF RESTRICTING

STREAM ACCESS BY ROTATIONAL GRAZING ON

CATTLE CONGREGATION IN OR NEAR PASTURE STREAMS IN TWO

YEARS(Haan et al., 2010)

May June July Aug Sept Avg02468

10121416 2006-07

CSU CSR RS RS (actual)

Month

% o

f obs

erva

tions

w

ithin

33

m o

f a

stre

am

May June July Aug Sept Avg0

0.51

1.52

2.53 2006-07

CSUCSRRS

Month

% o

f obs

erva

tions

in

stre

am

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

EFFECT OF SHORT-TERM ACCESS TO

OFFSTREAM WATER AND MINERAL

SUPPLEMENTATION ON CONGREGATION OF

CATTLE IN OR NEAR PASTURE STREAMS

May July Sept02468

10121416

2006-07

CSUCSU w/WCSRCSR w/W

% o

f obs

erva

tions

with

in 3

3 m

of

a st

ream

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedw/W or open = with offstream water and mineral

May June July August September0%

2%

4%

6%

8%

10%

12%

14%

16%2008-09

CSU ClosedCSU OpenCSR ClosedCSR Open

% o

f obs

erva

tions

with

in 3

3 m

of

a st

ream

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)

CONSIDER ENVIROMENTAL FACTORS

EFFECTS OF BLACK GLOBE TEMPERATURE-HUMIDITY INDEX ON THE PROBABILITY OF CONGREGATION OF CATTLE WITHIN 33 m OF A PASTURE STREAM IN TWO

GRAZING SEASONS

50 75 1000

0.05

0.1

0.15

0.2

0.25

0.3

CSU

CSR

Black globe temperature-humidity index

Estim

ated

Pro

babi

lity

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restricted

2008-09

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)

EFFECTS OF AMBIENT TEMPERATURE ON THE PROBABILITY OF COWS SEEKING SHADE

(Haan et al., 2010)

EFFECTS OF GRAZING MANAGEMENT ON NONPOINT SOURCE POLLUTION OF

PASTURE STREAMS

EFFECTS OF STOCKING RATE BETWEEN MEASUREMENT PERIODS ON STREAM BANK EROSION

MEASURED QUARTERLY ON 13 FARMS IN THE RATHBUN LAKE WATERSHED OVER THREE YEARS

EFFECTS OF GRAZING MANAGEMENT ON ANNUAL EROSION/DEPOSITION ACTIVITY AND NET EROSION

OF STREAM BANKS IN 2008 AND 2009

CSU CSR RS CSU CSR RSWinter Grazing Season

-10

-5

0

5

10

15

Net Erosion Erosion/deposition activity

cm

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

GRAZING MANAGEMENT MAY NOT ALWAYS PREVENT STREAM BANK EROSION

EFFECTS OF STOCKING RATE

BETWEEN BIMONTHLY MEASUREMENTS OF THE PROPORTION OF BARE AND MANURE-COVERED GROUND

WITHIN 50 FT OF STREAMS IN 13

PASTURES0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Period Cow-days / stream m

Aver

age

Bare

Gro

und,

%

0.0

0.5

1.0

1.5

2.0

2.5

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Period Cow-days / stream m

Man

ure-

Cove

red

Gro

und,

%

y = 10.4 + 3.73x – 0.314x2 (r2 =0.16)

y = 0.1 + 0.18x – 0.009x2 (r2 =0.35)

GRAZING SYSTEM EFFECTS ON PROPORTIONS OF BARE AND MANURE-COVERED GROUND

WITHIN 15 TO 110 FT OF PASTURE STREAMSM

ayJu

neJu

lyA

ugS

ept

Oct

May

June

July

Aug

Sep

tO

ct

May

June

July

Aug

Sep

tO

ct

May

June

July

Aug

Sep

tO

ct

2005 2006 2007 2008

0123456789

10CSUCSRRS

Year

% B

are

May

June

July

Aug

Sep

tO

ct

May

June

July

Aug

Sep

tO

ct

May

June

July

Aug

Sep

tO

ct

May

June

July

Aug

Sep

tO

ct

2005 2006 2007 2008

0

0.5

1

1.5

2

2.5

CSUCSRRS

Year%

Man

ure

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

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)

CSU Vege-tated

CSU Bare CSR Vege-tated

RS Vege-tated

RS Bare0

0.10.20.30.40.50.60.70.8

Runoff

Prop

ortio

n of

app

lied

CSU Vegeta

ted

CSU Bare

CSR Vegeta

ted

RS Vegeta

ted

RS Bare0

50010001500200025003000

Sediment

kg/h

a

CSU Vegeta

ted

CSU Bare

CSR Vegeta

ted

RS Vegeta

ted

RS Bare0

1000200030004000500060007000

Phosphorus

g/ha

a a

a

a

a

a

b bbb

bb

cc

c

CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO

ANNUAL SEDIMENT LOADING OF PASTURE STREAMS

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO

ANNUAL SEDIMENT LOADING OF PASTURE STREAMS

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO

ANNUAL PHOSPHORUS LOADING OF PASTURE STREAMS

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

CONTRIBUTIONS OF PRECIPITATION RUNOFF, DIRECT FECAL DEPOSITION, AND CUT BANK EROSION TO

ANNUAL PHOSPHORUS LOADING OF PASTURE STREAMS

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

GRAZING SYSTEMS EFFECTS ON

STREAM BANK EROSION

SUSCEPTIBILITY (1 – 60) AND

VEGETATION (1 – 4) SCORES OVER

FIVE YEARS

CSU = Continuous stocking unrestrictedCSR = Continuous stocking restrictedRS = Rotational stocking

ROLE OF GRAZING CATTLE ON PATHOGEN LOADING OF PASTURE

STREAMS

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

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

0.00 2.00 4.00 6.00 8.00 10.00 12.000.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00BEVincidyr

BCVincidyr

BRVincidyr

Cow-d/ft. stream

% in

cide

nce

of v

irus

es

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)

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

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)

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)

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

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???

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

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