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Window of Opportunity. Peter Scharf University of Missouri. Window of Opportunity?. Sensors. Factors defining the window. Effect of N timing on yield How late can you go? Effect of sensor timing on diagnostic accuracy How early can you go?. Effect of N timing on yield. tassel. - PowerPoint PPT Presentation
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Window of Opportunity
Peter ScharfUniversity of Missouri
Window of Opportunity?Window of Opportunity?
Sensors
Factors defining the window
Effect of N timing on yieldHow late can you go?
Effect of sensor timing on diagnostic accuracyHow early can you go?
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 4 8 12 16 20
growth stage of single N applic.
yiel
d r
elat
ive
to p
rep
lan
t N
missouri
nebraska
oklahoma
MO line
Effect of N timing on yield
tassel
How late can you apply?
Planned single application: as late as V11?Northern data needed
35 to 90 kg N/ha applied preplant
00.20.40.60.8
11.21.4
0 4 8 12 16 20
growth stage when balance of N applied
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
Effect of N timing on yield
tassel
How late can you apply?
Planned single application: as late as V11?Northern data needed
With modest preplant N: later yet
How late can you apply?
Planned single application: as late as V11?Northern data needed
With modest preplant N: later yet
As a rescue application: at least silking
Factors defining the window
Effect of N timing on yieldEffect of sensor timing on
diagnostic accuracy
Effect of sensor timing on accuracy
Can work as early as V6
Effect of sensor timing on accuracy
Chlorophyll meter prediction of N rate V5 to V9, R2 = 0.53 V10 to R1, R2 = 0.66
Chlorophyll meter: equation changes as season progresses
Prime window: V6 to V11?
Discussion?
Effect of N timing on yield
Russelle et al. 1983 Evanylo 1991 Jokela and Randall 1989 Sripada et al. 2005 Miller et al. 1975 Hoeft Bausch
Effect of N timing on yield depends on placement…
Broadcast
Between-row
0
2,000
4,000
6,000
8,000
10,000
0 30 60 90 120
Corn height (cm) when N was applied
Yie
ld (
kg h
a-1)
…and source (N burn)(average of 7 locations in Missouri, 2003-04)
TreatmentTreatment 1 foot1 foot 2 feet2 feet 3 feet3 feet 4 feet4 feet
Ammonium Ammonium nitratenitrate 11 88 2020 1818
28% N 28% N solutionsolution 99 1414 3333 6161
UreaUrea 00 00 XX 44
Yield loss (between-row minus broadcast) when 150 lb N applied broadcast at corn height:
Kansas producer 2006: 4000 Kansas producer 2006: 4000 acres of corn fertilized in six acres of corn fertilized in six days using sensorsdays using sensors
…and source (N burn)(average of 7 locations in Missouri, 2003-04)
TreatmentTreatment 1 foot1 foot 2 feet2 feet 3 feet3 feet 4 feet4 feet
Ammonium Ammonium nitratenitrate 11 88 2020 1818
28% N 28% N solutionsolution 99 1414 3333 6161
UreaUrea 00 00 XX 44
Yield loss (between-row minus broadcast) when 150 lb N applied broadcast at corn height:
Effect of N timing on yieldMissouri data, 28 expts. 1997-99
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 4 8 12 16 20
growth stage of single N application
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
tassel
Scharf et al., 2002, Agron. J. 94:435-441
Nebraska data, 2 expts. 1993-1994
0
0.2
0.4
0.6
0.8
1
1.2
0 4 8 12 16 20
growth stage of single N application
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
Effect of N timing on yield
tassel
Binder et al., 2000, Agron. J. 92:1228-1236
Oklahoma data, 5 expts. 2005-06
0
0.2
0.4
0.6
0.8
1
1.2
0 4 8 12 16 20
growth stage of single N application
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
Effect of N timing on yield
tassel
Walsh, 2006, MS Thesis
35 to 90 kg N/ha applied preplant
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 4 8 12 16 20
growth stage when balance of N applied
yie
ld r
ela
tiv
e t
o p
rep
lan
t N
nebraska
oklahoma
missouri
Effect of N timing on yield
tassel
Effect of N timing on yield
Producer N rate, Producer N rate, preplant vs preplant vs sidedress (on sidedress (on average V9)average V9)
Field-length stripsField-length strips
Effect of N timing on yield
YearYear # # expts.expts.
Yield effect of Yield effect of sidedresssidedress
20042004 77 -5-5
20052005 55 -16-16
20062006 55 +4+4
Yield effect is very weather-dependent!
Yield response to late N: Only when corn hasOnly when corn has visible N stress visible N stress
Greenness of corn
Yield response to N applied when corn was shoulder-high
100% 0 91% 10 77% 37
Steve Watkins farm, Hayti, 2000; research by Gene Stevens
Window of Opportunity: Later for unplanned (rescue) applications
Application until at least silking can give a large yield response when N stress is substantial
35 to 50 bu/ac in three MO tests
