Transcript Nitrogen Management for Wheat and Corn, What you Shouldn’t Do Y

U N I V E R S I T Y
S T A T E
O K L A H O M A
Nitrogen Management for
Wheat and Corn,
What you Shouldn’t Do
U N I V E R S I T Y
S T A T E
O K L A H O M A
Reference Strips (Schepers, Francis, UNL)
• Interfering factors present without them
–
–
–
–
Weed coverage in the center of the row
Low end could be due to something other than N
Valid paired comparisons
Scale between the bottom and the top must be
defined if it is going to be used for ensuing
recommendations
– N rate associated with high NDVI
– N rate associated with low NDVI
– Low NDVI could be due to water logging, low P, K,
etc.
O K L A H O M A
S T A T E
U N I V E R S I T Y
Near Marshall, OK - IKONIS NDVI
N Rich
No P
O K L A H O M A
1992
1993
S T A T E
U N I V E R S I T Y
O K L A H O M A
S T A T E
U N I V E R S I T Y
1993
1994
1995
1995
O K L A H O M A
S T A T E
U N I V E R S I T Y
1996
1996
1996
Variable Gain
1997
1998
1998
O K L A H O M A
S T A T E
U N I V E R S I T Y
2001
O K L A H O M A
S T A T E
U N I V E R S I T Y
• Pics of old sensors
2002
2003
Treat Temporal and Spatial Variability
Wheat, 0.4m2
Corn, by plant
O K L A H O M A
S T A T E
U N I V E R S I T Y
Variable Rate Technology
2007
O K L A H O M A
S T A T E
U N I V E R S I T Y
FLAT RATE
Argentina
Zimbabwe
Uzbekistan
Canada
U N I V E R S I T Y
S T A T E
O K L A H O M A
Some of our equipment is much
less complicated
1993, linear scale, uncalibrated red and NIR
1993-1995, variants of linear sufficiency
1995-1998, based of predicted yield potential YP0
1999, based on YP0 and RI (Wade Thomason)
2000, optimum resolution, 0.4m2 wheat
2002, RI NDVI, RI Harvest (Robert Mullen)
1999-2004, refinement of yield prediction
2005, YP0, RI, and CV, RAMP
2007, YP0, RI, CV, NUE
NDVI
Red
NDVI == NIR
NIR -- Red
Red
Red 620-750
620-750 nm
nm
NIR
NIR ++ Red
Red NIR
NIR 750-1x10
750-1x1066 nm
nm
Increased
Increased soil
soil background
background increased
increased red
red reflectance
reflectance 
 decreased
decreased NDVI
NDVI
In
In this
this region,
region, NDVI
NDVI is
is
influenced
influenced by
by
(a)
(a) color.
color.
In
In this
this region,
region, NDVI
NDVI is
is
influenced
influenced by
by
(a)
(a) soil
soil
(b)
(b) %
% coverage
coverage
(c)
(c) color
color
N Rate (lb N/ac)
U N I V E R S I T Y
S T A T E
•
•
•
•
•
•
•
•
•
00
10
10
20
20
30
30
40
40
50
50
60
60
70
70
80
80
0.2
0.2
50
50
40
40
30
30
20
20
10
10
0.3
0.3
0.4
0.4
0.5
0.5
NDVI
NDVI
0.6
0.6
0.7
0.7
0.8
0.8
N/ac)
(lb N/ac)
Uptake (lb
N Uptake
N
O K L A H O M A
Agronomic journey
“Starve the Rich”
Application Rate
Application Rate
“Feed the Rich”
NDVI
NDVI
RI =1.5
Compromise
Strategy
RI = 2.0
NDVI
Application Rate
Multiple Factors + N Limiting Yield
Application Rate
U N I V E R S I T Y
S T A T E
O K L A H O M A
Appropriate Strategy?
NDVI
O K L A H O M A
S T A T E
U N I V E R S I T Y
Variability in yield and nitrogen demand
U N I V E R S I T Y
Predicting Yield
Potential in Corn
INSEY
NDVI, V8 to V10
=
Days from planting to sensing
20
104-day (2003)
20 Locations, 2002-2005
Hybrid Corn, Mexico, Nebraska, Iowa,
Oklahoma, Virginia, Ohio
V8-V10 (44 to 69 days)
18
16
107-day (2003)
111-day (2003)
99-day (2004)
113-day (2004)
O K L A H O M A
Grain yield, Mg ha -1
S T A T E
14
105-day (2002)
109-day (2002)
1.7916
y = 19583x
R2 = 0.71
12
113-day (2002)
113-day (OFIT)
10
108-day (OFIT)
Efaw (2003)
8
LCB (2003)
Efaw (2004)
6
LCB 2004
Mexico (2002)
4
Shelton (2004)
0
0.002
Ames (2004)
CORN
2
0.004
0.006
0.008
0.01
INSEY
0.012
0.014
0.016
Ohio
0.018
RI=2.0
YPN
Grain yield
U N I V E R S I T Y
S T A T E
O K L A H O M A
RICV-NFOA
YP0
YPMAX
CV
CV
INSEY (NDVI/days from planting to sensing)
Nf = ((YP0*RI)*(100-CV/100-CVlim)) – YP0/ expected
NUE ??
U N I V E R S I T Y
200
0
15
O K L A H O M A
30
45
60
75
100
N Rate, lb/ac
200
30
15
S T A T E
RAMP Calibration
Strip
0
200
115
Limited differences by V8 in corn?
0N
Wheat N Ramp
O K L A H O M A
S T A T E
U N I V E R S I T Y
Ramp Calibration Strip
195 N
U N I V E R S I T Y
S T A T E
O K L A H O M A
10 on-farm trials, Triticum aestivum L.
avg. RI 1.3
Preplant
Early
Late
Total N
Yield
Return
Treatment
N rate,
lb/ac
Topdress
N
Topdress
N
rate,
lb/ac bu/ac
VRT
41
15
23
79
39.8
104
VS3
35
21
35
91
37.3
93
VS2
49
9
24
82
35.4
91
Farmer
Check
52
21
20
92
34.6
86
$/ac
U N I V E R S I T Y
S T A T E
O K L A H O M A
2007, Dryland, Zea mays L.
Preplant N,
lb/ac
Sidedress
N, lb/ac
Total N
Rate,
lb/ac
Yield, bu/ac
$/ac
N-Rich
200
0
200
88
216
SBNRC
0
45
45
73
234
SBNRC
40
28
68
85
266
Flat Rate
80
0
80
76
230
SBNRC, sensor based nitrogen rate calculator
NUE, 138 Site Years Corn, NE, WI, OH, OK, MN, 1969-2006
180
Yield increase, bu/ac
U N I V E R S I T Y
S T A T E
O K L A H O M A
NUE and Yield Increases, Zea mays L.
160
y = 145.73x - 5.9172
140
R2 = 0.69
120
100
80
60
40
20
0
0
0.1
0.2
0.3
0.4
0.5
NUE
0.6
0.7
0.8
0.9
1
U N I V E R S I T Y
S T A T E
0.9
O K L A H O M A
Can NUE be
determined for midseason N applications?
Ramps?
0.5
0.8
NUE = 0.40
0.7
NDVI
0.6
NUE = 0.60
0.4
0.3
0.2
0.1
120
0
0
50
100
150
N Rate, kg/ha
200
250
U N I V E R S I T Y
S T A T E
O K L A H O M A
Decision
• No need for reference strips
– Process of elimination, confounding factors, Liebig’s law of the
minimum
• Apply all N preplant, risk of mid-season applications is
just too high
– $0.46/ lb N, low NUE’s, environment, 1B excess N
• Use yield goals, less risky
– Yield prediction models corn, wheat, sorghum, canola, weather
data (MESONET)
• Apply same N rate year after year, less complicated
– Demand for N changes from year to year, as do NUE’s
U N I V E R S I T Y
S T A T E
O K L A H O M A
Extension
• Clint Mack, David Zavodny (586 Ramps 2006)
• County
Fert. Dealer
• Bob Woods
Danny Peeper
Stan Fimple
Brad Tipton
Chad Otto
Rodney King
Roger Gribble
2005-2007 (>2500)
Farmer acceptance?
U N I V E R S I T Y
O K L A H O M A
S T A T E
Thank you
www.nue.okstate.edu
Farmer training, Ciudad Obregon, Mexico, January 2007