1996 - D. a. Paice - Power Electronic Converter Harmonics_multipulse Methods for Clean Power
Threshold vs. adjusted dosage Svend Christensen and Torben Heisel, DIAS Mark Paice SRI.
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Threshold vs. adjusted dosage Svend Christensen and Torben Heisel, DIAS Mark Paice SRI
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Transcript of Threshold vs. adjusted dosage Svend Christensen and Torben Heisel, DIAS Mark Paice SRI.
Threshold vs. adjusted dosage
Svend Christensen and Torben Heisel, DIASMark Paice SRI
Blackgrass (Alopercurus myosuroides)
Old Seed Bank
Plants germinating
Herbicide -use
StochasticSeed Mortality
New SeedBank
Cost
StochasticGermination
Economic Model
Yield Loss
StochasticWeed Control
Plants surviving
Crop WeedCompetition
Seed Productionand Dispersal
Stochastic Seed
Mortality
Dose- response
New Seeds
Crop WeedCompetition
Initial Blackgrass Data
• Blackgrass density was measured in a 14 m x 14 m grid in a winter barley at Silsoe Research Institute
• The model unit was 1 m by 1 m cells
• Treatment unit was 4 m by 4 m cells
Spatial weed management of Blackgrass
• The threshold algorithm• PC-Plant Protection• DAPS (Decision Algorithm for Patch
Spraying)
The Threshold Algorithm
If Blackgrass density was higher than 1 plant m-2
A normal dose of 3.5 l ha-1 IPU was applied
PC-Plant Protection
A normal dose of 2.1l ha-1 IPU was applied
Input data Output data
Point or zone model
Competition model
PC-Plant Protection
Decision model
DAPS - Decision Algorithm for Patch Spraying
ResultsSeed Bank
Seeds/m2Year 02
0 m
The Threshold Algorithm
Seed
s/m2
Year 1
Seed
s/m2
Year 5
Seed
s/m2
Year 3S
eed
s/m2
Year 7
PC-Plant Protection
Seed
s/m2
Year 5
Year 1 Seed
s/m2
Seed
s/m2
Year 3S
eed
s/m2
Year 7
Decision algorithm for Patch Spraying
Seed
s/m2
Year 1
Year 3 Seed
s/m2
Seed
s/m2
Year 5 Seed
s/m2
Year 7
Yield loss (DKK ha-1)
Year Threshold PC-P DAPS
1 171 207 38
2 175 195 16
3 184 186 18
4 190 177 17
5 196 168 17
6 197 161 17
7 204 153 17
1317 1247 140
IPU dose (l ha-1)
Year Threshold PC-P DAPS
1 1.7 2.1 2.8
2 2.1 2.1 2.3
3 2.2 2.1 2.1
4 2.3 2.1 1.9
5 2.3 2.1 1.7
6 2.4 2.1 1.7
7 2.4 2.1 1.7
15.4 14.7 14.2
Cost (DKK ha-1)
Year Threshold PC-P DAPS
1 77 91 123
2 92 91 99
3 97 91 93
4 99 91 82
5 101 91 78
6 106 91 75
7 105 91 75
677 637 625
Model Assumptions
• The size of the treatment area affects the differences between the algorithm
• No spatially or temporally depended effect of soil conditions or cultivation factors on seed emergence, crop weed competition or seed production
