Predominant N Management Issues
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![Page 1: Predominant N Management Issues](https://reader035.fdocuments.in/reader035/viewer/2022062721/568138a8550346895da0677f/html5/thumbnails/1.jpg)
Improving NUE in Corn With Crop Sensing: Reflections, Concerns,
and Needed Research
Rain fed Southern Corn Belt
Improving NUE in Corn With Crop Sensing: Reflections, Concerns,
and Needed Research
Rain fed Southern Corn Belt
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Predominant N Management Issues
• Soil variability (some fields and soil types will be much better suited for sensor-driven N applications) alluvial >> loess > claypan
• Balance between meeting early N corn needs and not adding too much early such that the plant poorly predicts what the soil will provide
• If weather cooperates, N will be fall applied setting up a scenario of potential N loss
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Predominant N Management Issues
• Excessive spring and early summer rainfall setting up the need for a rescue
• Opportunity of application (can be especially narrow for poorly drained soils like the claypan soils)
• Hard to match side-dress UAN with preplant AA performance (source & placement issues)
• Hot & Dry weather (if only all growing seasons were like 2004)
• Shift of C-S to C-C with feed-to-fuel market shifts
![Page 4: Predominant N Management Issues](https://reader035.fdocuments.in/reader035/viewer/2022062721/568138a8550346895da0677f/html5/thumbnails/4.jpg)
• Scenarios that best fit sensor-driven N fertilizer applications:– Fields following wet spring and early summer
(loss of fall applied N)– Fields that have received recent manure
applications and uncertainty exists for how much N is available
– Fields receiving uneven N fertilization (fertilizer or manure)
– Fields coming out of pasture, hay, or CRP– Fields with extreme variability in soil type– Fields of corn-after-corn when drought occurred
the first year (i.e. non-uniform carry over)
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Other Thoughts and Reflections
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What will the impact of public What will the impact of public funding be on the future of VR funding be on the future of VR N management?N management?
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• Can a small nitrogen-rich reference area serve a large, variable field?• Will we eventually get by without a reference area within each field?
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0
25
50
75
100
-250 -200 -150 -100 -50 0 50 100 150 200
Difference from EONR, kg ha-1
Yie
ld E
ffic
ien
cy
, k
g g
rain
(k
g N
)-1 B04
CI04
CII04
D04
H04
P04
S04
W04
Yield efficiency (or NUE) not the same at EONR
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corn price ($/bu)cost of N ($/lb) $1.60 $1.80 $2.00 $2.20 $2.40 $2.60 $2.80 $3.00 $3.20
$0.15 10.7 12.0 13.3 14.7 16.0 17.3 18.7 20.0 21.3$0.20 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0$0.25 6.4 7.2 8.0 8.8 9.6 10.4 11.2 12.0 12.8$0.30 5.3 6.0 6.7 7.3 8.0 8.7 9.3 10.0 10.7$0.35 4.6 5.1 5.7 6.3 6.9 7.4 8.0 8.6 9.1$0.40 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0$0.45 3.6 4.0 4.4 4.9 5.3 5.8 6.2 6.7 7.1$0.50 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0 6.4$0.55 2.9 3.3 3.6 4.0 4.4 4.7 5.1 5.5 5.8$0.60 2.7 3.0 3.3 3.7 4.0 4.3 4.7 5.0 5.3
Issues of a changing EONR and reporting results
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0
25
50
75
100
-250 -200 -150 -100 -50 0 50 100 150 200
Difference from EONR, kg ha-1
Yie
ld E
ffic
ien
cy
, k
g g
rain
(k
g N
)-1 B04
CI04
CII04
D04
H04
P04
S04
W04
Yield efficiency related to EONR for 2004 fields
3.6 12.8
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-250 -200 -150 -100 -50 0 50 100 150
Difference from EONR, kg ha-1
Pro
file
Ino
rga
nic
N, k
g h
a-1 D04
P04
S04
Profile inorganic N related to EONR for 2004 fields
3.6 12.8
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When it comes to sensor indices….
• Some indices stretch out differences better than others: CHL index ~ simple ratio > NDVI
• Nice to have sensors output either Vis or NIR for purposes of indice performance testing
• NDVI and the simple ratio are mathematically related
Vissimple ratio = ---------------
NIR
NIR- VISNDVI = --------------------
NIR +VIS
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(1 – simple ratio)NDVI = -------------------------
(1 + simple ratio)
(1 – NDVI)simple ratio = -------------------------
(1 + NDVI)
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If n is our friend,
why is that N is our nemesis?
If n is our friend,
why is that N is our nemesis?