Atrazine Incorporation and Soil Erosion – Balancing Competing Water Quality Concerns for Claypan...
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Transcript of Atrazine Incorporation and Soil Erosion – Balancing Competing Water Quality Concerns for Claypan...
Atrazine Incorporation and Soil Erosion – Balancing Competing Water Quality Concerns for Claypan and
Restrictive Layer Soils
R. N. Lerch, C. M. Harbourt, R. R. Broz, and T. J. Thevary
ARS Field 1 near Centralia, MO
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Background - Claypan SoilsCentral Claypan Areaso Major Land Resource Area 113o Encompasses 33,000 km2 in MO and IL
Claypan Characteristicso Smectitic mineralogy (high shrink-
swell potential)• 40-60% clay content
o Near surface feature (0-60 cm)o Ksat <1 mm/so Claypan is an extreme form of an
argillic horizon Vulnerable to contaminant
transport in surface runoff • Soil-applied herbicides• Soil erosion
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Rationale A major challenge associated with claypan soils is the
need to develop cropping systems that concurrently facilitate incorporation of herbicides to reduce their transport in surface runoff, but maintain sufficient crop residue cover to control soil erosion (Lerch et al., 2008).
Conflicting Goalso No-till precludes the incorporation of herbicides. o Incorporation increases soil erosion
Conflicting goals require a balanced approach rather than managing for one problem at the expense of anothero Herbicide application methods must be found that can
incorporate soil-applied herbicides and maintain greater residue cover than commonly used reduced tillage systems, such as disc harrow or field cultivator.
No-Till Treatment; Simulation #3
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Objective Compare the effect of 3 tillage systems on sediment
and atrazine transport in surface runoffo Tillage treatments
• Phillips Harrow (Harrow)• No-Till• Field Cultivator (Minimum-Till)
o Data Collected• Hydrologic
Time to initiation of runoff, instantaneous discharge, and total volume
• Water Quality Suspended sediment (SS) concentration and load Atrazine concentration (by ELISA) and load
• Agronomic Residue cover, weed cover, corn yield
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Phillips Harrow• Roller harrow• Seedbed preparation• Maintains greater residue cover than
disc harrows or field cultivators• Incorporate herbicides (or fertilizer) to
~5cm depth• Working speeds up to 12 mph• Low horsepower requirements (90-130
hp)• High working capacity - >40 ac/hr for
the 45’ wide implement• One-pass spraying and incorporation -
can be equipped with spray nozzles and tanks
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Experimental DesignSite Description
Site located at the University of Missouri, Bradford Research and Extension Center
Soil Serieso Leonard Silt Loam, ~2% slopeo Common backslope claypan
soilo Managed as no-till corn-
soybean rotation for last 15 years (soybean in 2010).
Experiment conducted from 6/6 – 6/10/2011o No natural rainfall occurred!
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Experimental DesignPlot Layout
Each treatment was replicated six times in two sets of three plots.
S
N
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
S
N
Experimental DesignTillage Treatments
Phillips Harrowo Tilled with a disc harrow to 10 cm depth one week prior to experiment
• Intended to represent the expected residue cover from a conventionally managed corn-soybean rotation
o Atrazine applied at 2 lbs/ac, then incorporated with 2-passes to 3-5 cm depth.
o Operating speed was 8-9 mph (13-15 km/h). No-Till
o Atrazine applied at 2 lbs/ac Field Cultivator
o Disc harrow one week prior to experimento Atrazine applied at 2 lbs/ac, then incorporated with 2-passes to 10 cm
depth. All treatments
o Whole plot areas sprayed with Bicep (2 lbs/ac atrazine; 1.6 lbs/ac metolachlor) following rainfall simulations
o Corn planted on June 16, 2011Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Experimental DesignPlot Set-up
Site selection within the bulk plot based on minimizing side slope
0.25% or less Slopes
o Harrow – 2.1%o No-Till – 2.6%o Minimum-Till – 2.3%
Border steel installed to ~15 cm depth after herbicide spraying
Down slope section constructed with a diversion wall and metal gutter
Gutter attached to a PVC pipe to divert runoff to the sample bucket
Diversion wall
Gutter5 cm PVC pipe
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Runoff was generated using the HMWRS-001 rainfall simulator, designed by Waterborne Environmental, Inc. o Rainfall rate target for runoff collection was 27 mm/hro Rained on three sub-plots at a timeo Field operations were performed in the following sequence:
• Plots brought to saturation 48 hours before runoff collection• Plots sprayed 24-28 hours before runoff collection
Experimental DesignRainfall Simulation
Photo courtesy of Waterborne Environmental, Inc. Photo courtesy of Waterborne Environmental, Inc.
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Experimental DesignRunoff Collection
Instantaneous discharge o Determined by recording the
time to fill a 15-L bucketo Buckets composited in a 500-L
plastic barrel• Provided total runoff volume and
composite samples for atrazine and suspended sediment
Runoff Samples o Collected at 1, 5, 10, 15, 20, 30,
50, 70, and 90 minutes following the initiation of runoff.
o Samples analyzed for SS and atrazine concentration
Photo courtesy of Waterborne Environmental, Inc.
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Experimental DesignResidue Cover and Weed Control
Residue cover o Assessed on every runoff plot and 6 randomly chosen
areas within the bulk plots• Digital images acquired on 1 m2 areas using square borders
placed over the soil surface Weed control
o Six randomly chosen 1 m2 areas within the bulk plot (runoff plots excluded) were digitally photographed approximately two weeks after Bicep application and corn planting.
Images were analyzed for the fraction of the area covered by residue or weeds
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsHydrology
Mean Discharge
Harrow No-Till Minimum-Till
Dis
char
ge (L
/s)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07 Total Runoff Volume
Harrow No-Till Minimum-Till
Vol
ume
(L)
0
100
200
300
400(p = 0.797)(p = 0.797)
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsHydrology
ResultsHydrology
Rainfall Normalized Runoff Volume
Harrow No-Till Minimum-Till
Run
off V
olum
e (L
/mm
)
0
1
2
3
4
5
6
7(p = 0.005)
LSD0.05
a ab
Time to Initiation of Runoff
Harrow No-Till Minimum-Till
Tim
e (m
in)
0
20
40
60
80(p = 0.008)
LSD0.05
ab
a
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsErosion – SS Concentration
Suspended Sediment Concentration*
Harrow No-Till Minimum-Till
Sus
pend
ed S
edim
ent (
g/L)
0.00
0.20
0.40
0.60
0.80
Mean Rank of Suspended Sediment Concentrations
Harrow No-Till Minimum-Till
Mea
n R
ank
0
20
40
60
80
100
120
140
160(p < 0.0001)
*Median ± average absolute deviation
*CD0.05
a b
c
*Critical difference for
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsErosion – SS Loads
Suspended Sediment Load
Harrow No-Till Minimum-Till
Sed
imen
t Loa
d (g
)
0
50
100
150
200(p = 0.0002)
LSD0.05
a a
b
Rainfall Normalized SS Load
Harrow No-Till Minimum-TillS
edim
ent L
oad
(g/m
m)
0.0
0.5
1.0
1.5
2.0
2.5
3.0(p = 0.0002)
LSD0.05
a
b
a
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsAtrazine Concentrations
Harrow No-Till Minimum-Till
Atra
zine
con
cent
ratio
n (m
g L-1
)
0
500
1000
1500
2000
2500
3000
a
b
c
F-LSD0.05
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsAtrazine Concentrations
Time (minutes)0 10 20 30 40 50 60 70 80 90
Atra
zine
Con
cent
ratio
n (m
g/L)
0
500
1000
1500
2000
2500
3000
3500
4000Minimum-TillNo-Till Harrow
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
ResultsAtrazine Loads
Harrow No-Till Minimum-Till
Atra
zine
Loa
d (%
of A
pplie
d)
0
5
10
15
20
25
30
a a
b
Harrow No-Till Minimum-Till
Rai
nfal
l Nor
mal
ized
A
trazi
ne L
oad
(mg
mm
-1)
0
2
4
6
8
10
12
14
a
b
a
F-LSD0.05F-LSD0.05
A B
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Summary and Conclusions Hydrology
o No treatment differences in mean discharge or total runoff volumeo No-till significantly increased normalized runoff volume and decreased
time to initiation of runoff Erosion
o SS concentration: No-till < Harrow < Minimum-Tillo SS load: No-till = Harrow < Minimum-Till
Atrazineo Concentration: Minimum-Till < Harrow < No-Tillo Load: Minimum-Till = Harrow < No-Till
Supported other studies on claypan soils (Ghidey et al., 2005 and 2010): o Effectiveness of incorporation for reducing atrazine transport in runoffo No-till does not reduce runoff volume and greatly increases atrazine
losses on claypan soils Roller harrow achieved the needed balance by controlling
both erosion and atrazine lossesTranslating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Benefits of Roller Harrows Available tillage implement that is relatively low cost ($20-$40k)
Could readily replace disc harrows or field cultivators commonly used for seedbed preparation in corn production systems within the Central Claypan Areas
Improve sustainability of crop production by controlling erosion
Maintains farmer profitability
Improve the region’s two most persistent water quality problems by simultaneously managing the trade-off between erosion control and atrazine transport in runoff
Can be recommended as an atrazine BMP for claypan and restrictive layer soils!!
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO
Syngenta Corp. for the funding, and proposal review and field work assistance
Waterborne Environmental, Inc. field crew USDA-ARS field crew Kristi Perry and University Extension Todd Hensiek, Kane Holloway, and Tim McClintock
for the research on the roller harrow as part of their ASM capstone class (2009)
Acknowledgments
Minimum-Till Treatment; Simulation #5
Translating Missouri USDA-ARS Research and Technology into Practice A training session provided by USDA-ARS-CSWQRU, 10-11 October 2012, Columbia, MO