View
215
Download
1
Category
Tags:
Preview:
Citation preview
History of Predicting Yield PotentialHistory of Predicting Yield Potential
TEAM VRTOklahoma State UniversityTEAM VRTOklahoma State University
OutlineOutline Yield Goals and Potential Yield Soil Test vs. Sensor Based Sufficiency: Mobile vs. Immobile Nutrients Bray’s mobility concept How to generate nutrient recommendations What should we learn from soil testing Subsoil nutrient availability Soil Testing: Correlation/Calibration/Recommendation Models for Interpretation of Response Interfering agronomic factors
Yield Goals and Potential Yield Soil Test vs. Sensor Based Sufficiency: Mobile vs. Immobile Nutrients Bray’s mobility concept How to generate nutrient recommendations What should we learn from soil testing Subsoil nutrient availability Soil Testing: Correlation/Calibration/Recommendation Models for Interpretation of Response Interfering agronomic factors
Yield Goal/Potential YieldYield Goal/Potential Yield
Yield Goal: yield per acre you hope to grow (Dahnke et al., 1988)
Potential yield: highest possible yield obtainable with ideal management, FOR specific soil and weather conditions
Maximum Yield: grain yield achievable when all manageable growth factors (nutrients, insects, disease, and weeds) are nonlimiting and the environment is ideal
Yield Goal: yield per acre you hope to grow (Dahnke et al., 1988)
Potential yield: highest possible yield obtainable with ideal management, FOR specific soil and weather conditions
Maximum Yield: grain yield achievable when all manageable growth factors (nutrients, insects, disease, and weeds) are nonlimiting and the environment is ideal
Yield Goals in the LiteratureYield Goals in the LiteratureYield per acre you hope to grow (Dahnke et al. (1988).Highest yield attained in the last 4-5 years and that is
usually 30-33% higher than avg. yield (J. Goos, 1998).Aim for a 10-20% increase over the recent average (Rehm
and Schmitt, 1989).Yield goal should be based on how much water is available
(stored soil water to 1.5m, Black and Bauer, 1988).When Yield Goals are used it explicitly places the risk of
predicting the environment (good or bad) on the producer.
Yield per acre you hope to grow (Dahnke et al. (1988).Highest yield attained in the last 4-5 years and that is
usually 30-33% higher than avg. yield (J. Goos, 1998).Aim for a 10-20% increase over the recent average (Rehm
and Schmitt, 1989).Yield goal should be based on how much water is available
(stored soil water to 1.5m, Black and Bauer, 1988).When Yield Goals are used it explicitly places the risk of
predicting the environment (good or bad) on the producer.
Value of Using Yield GoalsValue of Using Yield GoalsValue of Using Yield GoalsValue of Using Yield Goals
Nutrient removal can be reliably estimated for a given yield level in specific crops.
Selected Yield Goal defines the risk the producer is willing to take. Yield Goal can define the limits in terms
of economic inputs when considering herbicides, insecticides, etc.
Nutrient removal can be reliably estimated for a given yield level in specific crops.
Selected Yield Goal defines the risk the producer is willing to take. Yield Goal can define the limits in terms
of economic inputs when considering herbicides, insecticides, etc.
Importance of Predicting Importance of Predicting Potential YieldPotential YieldImportance of Predicting Importance of Predicting Potential YieldPotential Yield
Seasonal N need directly related to observed yield.
NUE decreases with increasing N rate. Known Potential Yield = Known N Input =
Highest NUE.
Seasonal N need directly related to observed yield.
NUE decreases with increasing N rate. Known Potential Yield = Known N Input =
Highest NUE.
Max Yield Max Yield
YPYPMAXMAX
Max Yield Max Yield
YPYPMAXMAX
Ave
rag
e Y
ield
Ave
rag
e Y
ield
+30%+30%
Yie
ld G
oal
Yie
ld G
oal
YieldYield GoalGoalYieldYield GoalGoalPotentialPotential
YieldYieldYPYP00
PotentialPotentialYieldYieldYPYP00
Potential Potential Yield with Yield with
N, N, YPYPNN
Potential Potential Yield with Yield with
N, N, YPYPNN
Bound by Environment and ManagementBound by Environment and Management
Gra
in y
ield
Gra
in y
ield
Predicting N NeedsPredicting N NeedsPredicting N NeedsPredicting N Needs
Use of Yield Goals. Based on past season yields. May take into account current-year preplant
conditions of available moisture and residual N. Seldom is adjusted for midseason conditions to
alter N inputs. Use of Potential Yield.
Reliability of predicting final yield (and N requirement) from existing soil and crop conditions should increase as harvest approaches.
Use of Yield Goals. Based on past season yields. May take into account current-year preplant
conditions of available moisture and residual N. Seldom is adjusted for midseason conditions to
alter N inputs. Use of Potential Yield.
Reliability of predicting final yield (and N requirement) from existing soil and crop conditions should increase as harvest approaches.
Significant soil variability at distances less than 30 m apart (Lengnick, 1997)
In order to describe the variability encountered in field experiments, soil, plant and indirect measures should be made at the 1m or submeter resolution
Significant differences in soil test P, organic C, and pH were found at distances <0.30m (OSU)
Significant soil variability at distances less than 30 m apart (Lengnick, 1997)
In order to describe the variability encountered in field experiments, soil, plant and indirect measures should be made at the 1m or submeter resolution
Significant differences in soil test P, organic C, and pH were found at distances <0.30m (OSU)
Spatial Variability and Yield Spatial Variability and Yield PotentialPotentialSpatial Variability and Yield Spatial Variability and Yield PotentialPotential
Crop Response/Models to Crop Response/Models to Predict Yield (N need)Predict Yield (N need)Crop Response/Models to Crop Response/Models to Predict Yield (N need)Predict Yield (N need)
CERES (Crop-Environment Resource Synthesis) crop response model was not useful in predicting wheat grain yield (Moulin and Beckie, 1993) Complicated.
Total N uptake at Feekes growth stage 5 was found to be a good predictor of yield (Reeves et al., 1993) Worked some, but not all years.
CERES (Crop-Environment Resource Synthesis) crop response model was not useful in predicting wheat grain yield (Moulin and Beckie, 1993) Complicated.
Total N uptake at Feekes growth stage 5 was found to be a good predictor of yield (Reeves et al., 1993) Worked some, but not all years.
1. SF45 = (NDVI4 + NDVI5)/days from F4 to F5 INSEY (in-season-estimated-yield) GDD = (Tmin + Tmax)/2 – 4.4°C
2. EY = (NDVI4 + NDVI5)/GDD from F4 to F5 3. INSEY = (NDVI)/days from planting to
sensing 4. INSEY = (NDVI)/days from planting to
sensing where (GDD>0)
1. SF45 = (NDVI4 + NDVI5)/days from F4 to F5 INSEY (in-season-estimated-yield) GDD = (Tmin + Tmax)/2 – 4.4°C
2. EY = (NDVI4 + NDVI5)/GDD from F4 to F5 3. INSEY = (NDVI)/days from planting to
sensing 4. INSEY = (NDVI)/days from planting to
sensing where (GDD>0)
History of Predicting Potential History of Predicting Potential YieldYieldHistory of Predicting Potential History of Predicting Potential YieldYield
October February June0 120 240 days
October February June0 120 240 days
50 lb N /ac
100 lb N/ac
75 lb N/ac75 lb N/ac
N u
pta
ke, l
b/a
cN
upt
ake
, lb
/ac
INSEY: Rate of N uptake over 120 days, > ½ of the total growing days
and should be a good predictor of grain yield
INSEY: Rate of N uptake over 120 days, > ½ of the total growing days
and should be a good predictor of grain yield
45 bu/ac, 2.5% N in the grain
days with GDD>0?
October 1Benchmark Planting DateOctober 1Benchmark Planting Date
Planting DatePlanting Date
F4 DateF4 Date F5 DateF5 Date
20 143 185
6 116 145
Perkins
Tipton
42
29
Adj. Index
42+20=62
29+6=35
Adj. Index
42+20=62
29+6=35
Adjusting Yield PotentialAdjusting Yield PotentialAdjusting Yield PotentialAdjusting Yield Potential
Feekes growth stageFeekes growth stage
F4 F5 Maturity
growth
growth
ND
VI
ND
VI
NDVI min
SF45 = (NDVI4 + NDVI5)/days from F4 to F5SF45 = (NDVI4 + NDVI5)/days from F4 to F5
YIE
LD
PO
TE
NT
IAL
YIE
LD
PO
TE
NT
IAL
Feekes 4 Feekes 5 Grain YieldFeekes 4 Feekes 5 Grain Yield
40 20 50 50
Total N UptakeTotal N Uptake
0
1000
2000
3000
4000
5000
6000
0.01 0.02 0.03 0.04 0.05 0.06 0.07
NDVI F4+NDVI F5/days from F4 to F5NDVI F4+NDVI F5/days from F4 to F5
Gra
in Y
ield
Gra
in Y
ield
Perkins, N*P
Perkins, S*N
Tipton, S*N
y = 1E+06x2 - 12974x + 951.24R2 = 0.89
0 500 1000 1500 2000 25000 500 1000 1500 2000 2500
Ab
ov
e g
rou
nd
dry
w
eig
ht
Ab
ov
e g
rou
nd
dry
w
eig
ht
Cumulative growing degree daysCumulative growing degree days
NDVIT1 T2 NDVIT1 T2
Rickman, R.W., Sue E. Waldman and Betty Klepper. 1996. MODWht3: A development-driven wheat growth simulation. Agron J. 88:176 -185.
Rickman, R.W., Sue E. Waldman and Betty Klepper. 1996. MODWht3: A development-driven wheat growth simulation. Agron J. 88:176 -185.
14
12
10
8
6
4
2
0
14
12
10
8
6
4
2
0
INSEY = (NDVIT1 + NDVIT2)/GDD T1 to T2INSEY = (NDVIT1 + NDVIT2)/GDD T1 to T2
GDDGDD
y = 962 exp 92.6x
r2 = 0.50
0
1000
2000
3000
4000
5000
6000
7000
0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018
Estimated Yield (EY)
Mea
sure
d gr
ain
yiel
d, k
g ha
-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
9 experiments (NDVI F4 + NDVI F5/GDD from F4 to F59 experiments (NDVI F4 + NDVI F5/GDD from F4 to F5
y=572 exp150.2x
r2 = 0.83
0
1000
2000
3000
4000
5000
6000
7000
0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018
Estimated Yield (EY)
Mea
sure
d gr
ain
yiel
d, k
g ha
-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
Experiment 222, 1999
Experiment 301, 1999
Experiment 801, 1999
6 experiments (NDVI F4 + NDVI F5/GDD from F4 to F56 experiments (NDVI F4 + NDVI F5/GDD from F4 to F5
Field Experiments, 1998-2000._____________________________________________________________________________________________Experiment Location Year Date Planting Harvest Variety Planting to
Sensed date date sensing,D/M/Y D/M/Y D/M/Y days
S*N§ Perkins, OK 1998 6/4/98 21/10/97 15/6/98 Tonkawa 167S*N§ Tipton, OK 1998 26/2/98 7/10/97 3/6/98 Tonkawa 142N*P¶ Perkins, OK 1998 2/4/98 21/10/97 15/6/98 Tonkawa 163N*P¶ Perkins, OK 1999 4/3/99 12/10/98 9/6/99 Tonkawa 143Experiment 222 Stillwater, OK 1999 24/2/99 13/10/98 15/6/99 Tonkawa 134Experiment 301 Efaw, OK 1999 24/3/99 15/10/98 15/6/99 Tonkawa 160Efaw AA Efaw, OK 1999 24/3/99 9/11/98 15/6/99 Tonkawa 135Experiment 502 Lahoma, OK 1999 5/3/99 9/10/98 30/6/99 Tonkawa 147Experiment 801 Haskell, OK 1999 23/3/99 16/10/98 6/7/99 2163 158N*P Perkins, OK 2000 8/2/00 8/10/99 30/5/00 Custer 123Experiment 222 Stillwater, OK 2000 6/3/00 7/10/99 6/7/00 Custer 151Experiment 301 Efaw, OK 2000 6/3/00 7/10/99 2/6/00 Custer 151Efaw AA Efaw, OK 2000 6/3/00 7/10/99 7/7/00 Custer 151Experiment 801 Haskell, OK 2000 14/3/00 8/10/99 2/6/00 2137 158Experiment 502 Lahoma, OK 2000 13/3/00 12/10/99 13/6/00 Custer 153Hennessey AA Hennessey, OK 2000 13/3/00 7/10/99 7/6/00 Custer 158
Field Experiments, 1998-2000._____________________________________________________________________________________________Experiment Location Year Date Planting Harvest Variety Planting to
Sensed date date sensing,D/M/Y D/M/Y D/M/Y days
S*N§ Perkins, OK 1998 6/4/98 21/10/97 15/6/98 Tonkawa 167S*N§ Tipton, OK 1998 26/2/98 7/10/97 3/6/98 Tonkawa 142N*P¶ Perkins, OK 1998 2/4/98 21/10/97 15/6/98 Tonkawa 163N*P¶ Perkins, OK 1999 4/3/99 12/10/98 9/6/99 Tonkawa 143Experiment 222 Stillwater, OK 1999 24/2/99 13/10/98 15/6/99 Tonkawa 134Experiment 301 Efaw, OK 1999 24/3/99 15/10/98 15/6/99 Tonkawa 160Efaw AA Efaw, OK 1999 24/3/99 9/11/98 15/6/99 Tonkawa 135Experiment 502 Lahoma, OK 1999 5/3/99 9/10/98 30/6/99 Tonkawa 147Experiment 801 Haskell, OK 1999 23/3/99 16/10/98 6/7/99 2163 158N*P Perkins, OK 2000 8/2/00 8/10/99 30/5/00 Custer 123Experiment 222 Stillwater, OK 2000 6/3/00 7/10/99 6/7/00 Custer 151Experiment 301 Efaw, OK 2000 6/3/00 7/10/99 2/6/00 Custer 151Efaw AA Efaw, OK 2000 6/3/00 7/10/99 7/7/00 Custer 151Experiment 801 Haskell, OK 2000 14/3/00 8/10/99 2/6/00 2137 158Experiment 502 Lahoma, OK 2000 13/3/00 12/10/99 13/6/00 Custer 153Hennessey AA Hennessey, OK 2000 13/3/00 7/10/99 7/6/00 Custer 158
Normalized Difference Vegetation Index (NDVI)
= NIR ref – red ref / NIR ref + red ref
Normalized Difference Vegetation Index (NDVI)
= NIR ref – red ref / NIR ref + red ref
(up – down)(up – down)
excellent predictor of plant N uptakeexcellent predictor of plant N uptake
0
20
40
60
80
100
120
140
160
180
200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
NDVI, Feekes 4-6
Ea
rly-
sea
son
pla
nt N
up
take
, kg
ha-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
transect Stillw ater, 1999
transect Perkins, 1999
transect Efaw , 2000, Jan
transect Perkins, 2000 Jan
transect Efaw , 2000 Mar
transect Perkins, 2000 Mar
y = 1019.5x3 - 1507.5x2 + 811.5x - 130.32R2 = 0.78
0
20
40
60
80
100
120
140
160
180
200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
NDVI, Feekes 4-6
Ea
rly-
sea
son
pla
nt N
up
take
, kg
ha-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
transect Stillw ater, 1999
transect Perkins, 1999
transect Efaw , 2000, Jan
transect Perkins, 2000 Jan
transect Efaw , 2000 Mar
transect Perkins, 2000 Mar
y = 1019.5x3 - 1507.5x2 + 811.5x - 130.32R2 = 0.78
Units:
N uptake, kg ha-1
Units:
N uptake, kg ha-1
October February June0 120 240 days
October February June0 120 240 days
50 lb N /ac
100 lb N/ac
75 lb N/ac75 lb N/ac
N u
pta
ke, l
b/a
cN
upt
ake
, lb
/ac
INSEY: Rate of N uptake over 120 days, > ½ of the total growing days
and should be a good predictor of grain yield
INSEY: Rate of N uptake over 120 days, > ½ of the total growing days
and should be a good predictor of grain yield
45 bu/ac, 2.5% N in the grain
days with GDD>0?
y = 4.2419x3 - 2.8688x2 + 3.3405x
R2 = 0.53
0
1
2
3
4
5
6
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
NDVI, Feekes 4-6
Gra
in Y
ield
, Mg
kg
ha
-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
Normalized Difference Vegetation Index (NDVI)
Reasonably good predictor of final grain yield
Normalized Difference Vegetation Index (NDVI)
Reasonably good predictor of final grain yield
0
1
2
3
4
5
6
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007
EY
Gra
in y
ield
, M
g h
a-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
T1T1
GDD from T1 to T2GDD from T1 to T2
NDVIT2NDVIT2NDVINDVIEstimatedYield (EY) EstimatedYield (EY)
+Good predictor of final grain yield- Requires two sensor readings +GDD+Good predictor of final grain yield- Requires two sensor readings +GDD
y = 0.4554e344.12x
R2 = 0.62
0
1
2
3
4
5
6
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007
INSEY
Gra
in Y
ield
, Mg
ha
-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
y = 4E+07x3 - 296260x2 + 970.66x
R2 = 0.64
NDVI at F5 NDVI at F5 In-SeasonEstimatedYield (INSEY)1
In-SeasonEstimatedYield (INSEY)1
days from planting to F5 days from planting to F5
+Good predictor of final grain yield+Requires only one sensor reading+Good predictor of final grain yield+Requires only one sensor reading
Units:
N uptake, kg ha-1 day-1
Units:
N uptake, kg ha-1 day-1
0
1
2
3
4
5
6
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008
INSEY (NDVI Feekes 4-6/days from planting to Feekes 4-6)
Gra
in Y
ield
, M
g h
a
-1
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
VIRGINIA (7 Loc's)
NDVI at F5 NDVI at F5 In-SeasonEstimatedYield (INSEY)1
In-SeasonEstimatedYield (INSEY)1
days from planting to F5 days from planting to F5
Hard Red Winter Wheat (Oklahoma)Soft White Winter Wheat (Virginia)Hard Red Winter Wheat (Oklahoma)Soft White Winter Wheat (Virginia)
NDVI at F5 NDVI at F5 In-SeasonEstimatedYield (INSEY)2
In-SeasonEstimatedYield (INSEY)2
days from planting to F5, GDD>0 days from planting to F5, GDD>0
+Good predictor of final grain yield+Requires only one sensor reading+Appears to work over different regions
+Good predictor of final grain yield+Requires only one sensor reading+Appears to work over different regions
Units:
N uptake, kg ha-1 day-1 where GDD>0
Units:
N uptake, kg ha-1 day-1 where GDD>0
0
1
2
3
4
5
6
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01
INSEY=NDVI5/Days(GDD>0)
Yie
ld (
Mg
/ha
)
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
NDVI at F5 NDVI at F5 In-SeasonEstimatedYield (INSEY)2
In-SeasonEstimatedYield (INSEY)2
days from planting to F5, GDD>0 days from planting to F5, GDD>0
0
1
2
3
4
5
6
0 0.002 0.004 0.006 0.008 0.01 0.012
INSEY=NDVI5/Days(GDD>0)
Yie
ld (
Mg
/ha
)
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
Virginia
Hard Red Winter Wheat (Oklahoma)Soft White Winter Wheat (Virginia)Hard Red Winter Wheat (Oklahoma)Soft White Winter Wheat (Virginia)
y = 0.5643e279.42x
R2 = 0.6476
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0 0.002 0.004 0.006 0.008
INSEY=NDVI/days from planting, GDD>0
Gra
in y
ield
, M
g/h
a Soft White Winter Wheat7 locations in Virginia, 2001
Soft White Winter Wheat7 locations in Virginia, 2001
Spring Wheat 2001-2004
0123456789
10
0 0.005 0.01 0.015 0.02
INSEY
Me
as
ure
d Y
ld, M
g/h
a
Measured Yield
Avg Yld = 0.7418 e^(130.65 INSEY) R2=0.6403
Avg Yld +1 Std Dev= 0.9897e^(130.65 INSEY)
Spring Wheat 2001-2004
0123456789
10
0 0.005 0.01 0.015 0.02
INSEY
Me
as
ure
d Y
ld, M
g/h
aMeasured Yield
Avg Yld = 0.7418 e^(130.65 INSEY) R2=0.6403
Avg Yld +1 Std Dev= 0.9897e^(130.65 INSEY)
Can We Predict Yield with No Additional N Applied?
YP0
Can We Predict The Yield Increase If We Apply N in a Given Year?
YPN
Can We Predict if Harvested Yield will be Less than Predicted Yield?
YP?
Can We Predict Yield with No Additional N Applied?
YP0
Can We Predict The Yield Increase If We Apply N in a Given Year?
YPN
Can We Predict if Harvested Yield will be Less than Predicted Yield?
YP?
12
10
8
6
4
2
0
12
10
8
6
4
2
0
Abo
ve g
roun
d dr
y w
eigh
tA
bove
gro
und
dry
wei
ght
Cumulative growing degree daysCumulative growing degree days
Harvest
0
1000
2000
3000
4000
5000
6000
0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018
INSEY
Obs
erve
d gr
ain
yiel
d, k
g/ha
Post-maturity yield lossPost-maturity yield loss
R-NH2R-NH2
NO3- + 2e (nitrate reductase) NO2
- + 6e (nitrite reductase) NH4+NO3
- + 2e (nitrate reductase) NO2- + 6e (nitrite reductase) NH4
+
NH3NH3
R-NH2
NO3
NH4
R-NH2
NO3
NH4
REPRODUCTIVEREPRODUCTIVEVEGETATIVEVEGETATIVE
moistureheatmoistureheat
Total NTotal N
Total N
aminoaminoacidsacidsNHNH 33
nitrite reductasenitrite reductasenitrate reductasenitrate reductase
NO 2NO 3
SafetyvalveSafetyvalve
12
10
8
6
4
2
0
12
10
8
6
4
2
0
Ab
ove
gro
und
dry
we
igh
tA
bov
e g
rou
nd d
ry w
eig
ht
Cumulative growing degree daysCumulative growing degree days
Harvest
RainfallDiseaseFrost
RainfallDiseaseFrost
0
1000
2000
3000
4000
5000
6000
0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018
INSEY
Ob
serv
ed
gra
in y
ield
, kg
/ha
October February JuneOctober February June
N u
pta
ke, l
b/a
cN
upt
ake
, lb
/ac
40 N
0 N
Predicting the Increase in Yield due to Applied N
NEXT Section…… ????
Recommended