Transcript Nitrogen Management and its Influence on N Losses to

Using Corn Nitrogen Response
Data for Developing an Algorithm
for Minnesota
Jeff Vetsch1, Gyles Randall1, and Nyle
Wollenhaupt2
Univ. of Minnesota1 and AGCO2
7/17/2015
Tools for Developing an N Algorithm
for Corn in Minnesota
• Chlorophyll meter
– Positives
• Experience, lots of data
– Negatives
• Time consuming, works best after V10 (too late)
• GreenSeeker sensor
• Crop Circle sensor
• Aerial photography and imaging
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Definitions / Methods
• Delta NDVI = NDVI (fertilized) – NDVI (check)
• Delta Yield = Grain yield (fert.) – yield (check)
• Response Index (RI)
– RI NDVI = NDVI (fertilized) / NDVI (check)
– RI Yield = Yield (fertilized) / Yield (check)
• Economic Optimum N Rate (EONR)
– Calclated from N rate studies with quadratic or QP
models
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Relative chlorophyll vs N rate at V12
100
R e l. C h lo ro p h yll, %
95
90
85
80
75
70
0
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50
100
N R a te , lb /A
150
200
250
GreenSeeker NDVI as affected by N rate
0 .6
0 .5
N D V I (V 8 )
0 .4
0 .3
0 .2
0 .1
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0
50
100
P re p la n t N R a te , lb /a cre
150
200
GreenSeeker Sensor – Delta NDVI (2004)
140
120
Waseca: clay loam,
corn after corn
0
0
0
D e lta yie ld , b u /a
100
40
80
0
60
40
40
120
80
80
40
200
14200
160
20
80
0
21021006 0
0 .0 0
160
0 .0 2
Delta yield =
(Max yield (ref) –
ind. plot yield)
160
200
200
120
80
0 .0 4
0 .0 6
0 .0 8
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D e lta N D V I a t V 8
0 .1 0
0 .1 2
0 .1 4
GreenSeeker Sensor - Delta NDVI (2005)
160
140
SE MN site: silt loam,
corn after corn
0
120
0
0
D e lta yie ld , b u /a
0
100
40
80
40
40
40
80
60
80
80
80
40
120
20
0
120
120
160 160
2 01 6 0
16
220000
0 .0 0
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200 200
0 .0 5
0 .1 0
0 .1 5
D e lta N D V I a t V 7 -8
0 .2 0
0 .2 5
GreenSeeker RI affected by growth stage
Corn after Corn
1.40
1.35
R I (N D V I)
1.30
1.25
1.20
1.15
1.10
1.05
1.00
40
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45
50
55
60
Days from planting to sensing
65
70
75
Insey not correlated with RI
Corn after corn
1.40
R I (N D V I)
1.30
1.20
1.10
1.00
0.007
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0.009
0.011
INSEY
0.013
0.015
GreenSeeker (V7-9) - Response Index (2004-05)
4.0
R-square = 0.70
y = -2.96 + 4.05x
R I (G ra in yie ld )
3.5
3.0
2.5
2.0
1.5
1.0
1
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1.1
1.2
1.3
RI (NDVI)
1.4
1.5
1.6
GreenSeeker at V7-8
220
PP
E O N R (lb N /A )
200
Split
R-square = 0.62 and 0.57
180
160
140
120
100
80
1
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1.05
1.1
1.15
1.2
RI (NDVI)
1.25
1.3
1.35
1.4
By rep data at V7-9 (2004-05)
250
E O N R (lb N /A )
PP
Split
Silt loam soil; more responsive
200
150
100
50
1
1.1
1.2
1.3
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RI (NDVI)
1.4
1.5
1.6
By rep data at V7-9 (2004-05)
250
E O N R (lb N /A )
PP
R-square = 0.54
Split applied and one
high RI data removed
200
150
100
50
1
1.1
1.2
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RI (NDVI)
1.3
1.4
Crop Circle Sensor (2006)
Treatment Mean RI = 1.10
NDVI versus Preplant N Rate (Treatments 1-6) y = -4E-06x 2 + 0.001x + 0.6569
R2 = 0.8885
0.74
NDVI
0.72
0.7
Avg NDVIR
Poly. (Avg NDVIR)
0.68
0.66
0.64
0
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50
100
150
Preplant N (lb/ac)
200
Observations
• The Delta (NDVI or yield) approach is very
similar to a response index approach,
however RI is slightly less variable.
• GreenSeeker RI declines after V9, thus target
application/sensing at V8.
• GreenSeeker RI explained 70% of the
variation in corn yield response to N “RI”.
• GreenSeeker RI explained up to 62% of the
variation of EONR across multiple site-years.
• Best chance for success in corn after corn.
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Future: Algorithm development and inseason application (recommendations)
• More N rate sites – targeted (V7-8) sensing
with GreenSeeker and Crop Circle sensors
• In-season N recs.
– Baby step approach
• Measure RI by “calibration stamp” method, use RI to
improve upon current N recs (single rate for a field).
– Advanced approach “hog wild approach”
• Use RI and variability in “farmer practice” across
landscape to determine variable rate recs for a field
(MUCH MORE RESEARCH NEEDED).
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Example: Baby step approach
Minnesota - CC
140
0.05
0.10
0.15
0.20
Return to N, $/acre
120
100
80
60
40
20
0
0
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50
100
150
N Rate, lb N/acre
200
250