Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based...
Click here to load reader
Transcript of Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based...
![Page 1: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/1.jpg)
Herbicide-Soil Interactions
Bob HartzlerExtension Weed ScienceDepartment of Agronomy
![Page 2: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/2.jpg)
Herbicide Application Timing.% Acres Treated - 1985
Corn SoybeanEarly Preplant 10 5PP Incorporated 50 85Preemergence 36 20TOTAL Residual 96 100Postemergence 35 16
Wintersteen and Hartzler. 1987. Pm-1288.
![Page 3: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/3.jpg)
Fate of Soil-Applied Herbicides
![Page 4: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/4.jpg)
Desorption
Adsorption
Pools of Herbicide in Soil
Bound to soil
In soilsolution
![Page 5: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/5.jpg)
Desorption
AdsorptionBound to
soil
In soil solution
Pools of Herbicide in Soil
![Page 6: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/6.jpg)
Soil Properties InfluencingHerbicide Adsorption• Mineral components
– Sand– Silt– Clay
• Organic matter (humus)– 4 to 20 times more adsorptive than clay
![Page 7: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/7.jpg)
Organic matter vs crop residue
![Page 8: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/8.jpg)
Retention of atrazine on crop residue
0 0.2" 0.5" 1.0"0
20
40
60
80
100
Soil Residue
% o
f app
lied
herb
icid
e
Cumulative rainfall
Ghadiri et al. 1984. Univ. Nebraska
![Page 9: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/9.jpg)
AirH2O
KD = Amount on soil / Amount in water
KD= 721 molecules bound / 3
free
Soil AirH2OSoil KD= 2424 molecules bound / 1
free
Sorption Coefficient
H H
H
H
H
HH
H
H
H
H H
H
HH
HH
H
H
H
H
H
H
HH H
H
H
HH
H
H H
H
HHH
H
H
H
H
H
HH
H
H
H
H
H
![Page 10: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/10.jpg)
Herbicide SorptionHerbicide Koc
paraquat 100,000
glyphosate 24,000
trifluralin 7000
atrazine 100
dicamba 6
![Page 11: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/11.jpg)
Herbicide rates by soil type
Corvus rate recommendations (fl oz)Coarse soils, 2.0 % OM or less All other soils
3.33 5.6
Metribuzin rate recommendations (lbs)< 2% OM 2 to 4% OM > 4% OM
Coarse Do not use ½ 2/3
Medium ½ to 2/3 2/3 to 5/6 5/6 to 1
Fine 2/3 to 5/6 5/6 to 1 1 to 1 1/6
![Page 12: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/12.jpg)
Influence of soil pH on soil relations of herbicides • Triazines
– High pH: less adsorption, greater persistence• Sulfonylureas
– High pH: greater persistence• Imidazolinones, isoxaflutole
– Low pH: greater persistence
![Page 13: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/13.jpg)
Influence of Rain on PRE Herbicide Performance• Leaching
– Pro: Move to depth where weed seeds germinate
– Con: Can dilute herbicide and reach tile lines/groundwater
• Amount of herbicide in solution
![Page 14: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/14.jpg)
Herbicide Activation
Herbicide
Soil profile(upper 2”)
![Page 15: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/15.jpg)
Movement of two herbicides through soil1 (six inches rain)
Depth (in) AlachlorKoc = 124
MetribuzinKoc = 60
0-3 95% 88%
3-6 5% 10%
6-12 0% 2%
Amount remaining 20 DAA 30% 37%
Jones et al. 1990. Weed Sci. 38:589-597.
1Sandy loam, 0.6% OM
![Page 16: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/16.jpg)
Soil Moisture Affect on Herbicide Availability
Moist soilH2O
KD = Amount in soil / Amount in water
HH
H
H
H
H
HH
H
H
H
H H
H
HH
HH
H
H
H
H
Example : KD = 7
H
H
H
Soil AirH2O
HH
H
H
H
H
HH
H
H
H
H H
H
HH
HH
H
H
H
H
H H
H
Soil
H
H HH
H
H
HH
HH
HH
H
H
Dry soil
![Page 17: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/17.jpg)
Herbicide degradation
0 1 2 3 4 5 6 7 8Weeks after planting
100
80
60
40
20
0
LD95%
Extr
a ki
lling
pow
er
![Page 18: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/18.jpg)
Factors influencing degradation• Herbicide properties• Environment
– Rainfall– Temperature
• Soil characteristics– pH (certain herbicides)
![Page 19: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/19.jpg)
Enhanced herbicide degradation
0 1 2 3 4 5 6 7 8Weeks after planting
100
80
60
40
20
0
LD95%
History soil
1970’s - Eradicane, Sutan+
2000’s - atrazine Non-history soil: ½ life = 17 days History soil: ½ life = 9 days
![Page 20: Crop Management - Dr. Robert G. Hartzler, Iowa State University - Pesticide Application Rate Based on Soil Type](https://reader037.fdocuments.in/reader037/viewer/2022102322/54c2b2854a795941798b4577/html5/thumbnails/20.jpg)
Summary• Only a small fraction of PRE herbicides
is absorbed by plants• Only herbicide present in soil water
available for absorption by weeds• Sorption characteristics of a herbicide
critical in determining performance