Corn Nitrogen Fertilization Algorithm

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Corn Nitrogen Fertilization Algorithm
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Approach
Predict Yield Potential Mid SeasonPredict
Responsiveness to Applied N Project N Uptake
Difference (Fertilized Non
Fertilized)Project N Rate Based on the
Difference
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Farmer Practice
N Rich Strip

1. Yield Prediction, or YP0 (Farmer Practice)
2. Predict Response Index or RI (NDVI N Rich/NDVI
   Farmer Practice)
3. Measure CV in Farmer Practice
4. Estimate of Plant Population
5. Yield Achievable with N (YP0RI)
6. Yield Achievable Adjusted based on CV and
   Population
7. N uptake Difference using a fixed N (6 1)
8. N rate Determined by Dividing N uptake
   Difference/ Efficiency Factor

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NDVI at F5

INSEY
Days from planting to sensing, GDDgt0
Winter Wheat
Units biomass, kg/ha/day where GDDgt0
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NDVI, V8 to V10

INSEY
Days from planting to sensing
Corn
Units biomass, kg/ha/day
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Long-Term N Fertilization Experiment in Corn,
Mead, NE 1969-1983
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Yield Prediction Equations
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8.9
6.3 Mg 80.0 kg N
1975 2.5
11.3
1978 7.4
3.8 Mg 48.6 kg N
Difference in Grain N Uptake of 31.4 kg NAt an
application efficiency of 50, 1.25 Grain NN
Fertilizer Requirement Differed by 62.8 kg N
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Predicting RI in Corn
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RI-NFOAYPNYP0 RI
YP0
YPN
YPN
YPMAX
RI1.5
RI2.0
Grain yield
INSEY (NDVI/days from planting to sensing)
Nf (YP0RI) YP0))/Ef
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Aug 16, 2002
Aug 28, 2002
Nov 7, 2002
Previous Nitrogen Fertilizer Optimization
Algorithm
1. Establish preplant N Rich Strip(NRS) 4.
Determine Response Index (RI)2. NDVI (biomass)

NDVINRS/NDVIFarmer3. Predict potential yield
5. Predict potential
grain yield need of days from planting to
(YP0) with added N, YPN (YP0RI)
sensing (INSEY biomass prod./day) 6.
Fertilizer Rec (grain N uptake INSEY vs.
Yld eqn. YPN
grain N uptake YP0/0.6)
CORN
YPN
RI
May
June
August
NDVI (sensing date)
YP0
Planting date
days from planting to sensing
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RICV-NFOA
RI2.0
YP0
YPN
YPMAX
CVlim 65 (corn)CVlim 40 (wheat)
CV
Grain yield
CV
INSEY (NDVI/days from planting to sensing)
YPN YP0RI CrCV (((-0.0003)POP)36.315) YPCV
YPN((65-CV)/(65-CrCV)) NRate
((YPCV-YP0)0.0125/0.6)
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Use of Population and CV
RI NRichStrip/FarmerPractice YP0
((1565EXP((FarmerPractice/Days)154.7))) RI
(NRichStrip/FarmerPractice)1.64 - 0.5287 YPN
YP0RI CrCV (((-0.0003)POP)36.315) YPCV
YPN((65-CV)/(65-CrCV)) NRate
((YPCV-YP0)0.0125/0.6)
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Rainfed and Irrigated Corn
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Yield Prediction Equations
Condition Crop Year Equation Units plus 1 SD Yrs Loc RI Adjustment Equation
Dryland Winter Wheat  2002 YP0344EXP(INSEY267.65) kg/ha yes 4 22  
Dryland Winter Wheat  2003 YP0500EXP(INSEY267.65) kg/ha yes 5 26
Dryland Winter Wheat 2004 YP0359EXP(INSEY324.4) kg/ha yes 6 30
Dryland Winter Wheat 2005 YP0522EXP(INSEY274.7) kg/ha yes 7 34 RI Harvest 1.69(RI-NDVI) -0.70
Irrigated Corn 2003 YP02332.9(EXP(INSEY132.46) kg/ha
Dryland Corn 2003 YP01633(EXP(INSEY132.46) kg/ha
Dryland Irrigated Corn 2004 YP01565(EXP(INSEY154.7) kg/ha yes 3 7 RI Harvest 1.64(RI-NDVI) - 0.5287
Irrigated Corn (2nd planting, Argentina) 2005 YP0624(EXP(INSEY149.41)
Irrigated Spring Wheat 2003 YP0701EXP(INSEY154.91) kg/ha yes 3 6  
Irrigated Spring Wheat 2004 YP0989EXP(INSEY130.65) kg/ha yes 4 11
Dryland Spring Wheat Canada 2005 YP0 1659(exp(732.72INSEY)) kg/ha yes 1
Dryland Canola Canada 2005 YP01408.3exp(744.61INSEY) kg/ha yes 1
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Response Index vs. Sufficiency