impairments to iowa’s water resources 2008 impaired waters list (357 streams & 77 lakes)
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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
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