Adjusting Mid-Season Nitrogen Fertilizer Using a Sensor-Based

Optimization Algorithm to Increase Use Efficiency in Corn

B. Tubana, R. Teal, K. Freeman, B. Arnall, B. Chung, O. Walsh, K. Lawles, C. Mack and W. Raun

Annual ASA Meeting, Indianapolis9:30 am, Nov. 15, 2006

Presentation Outline

•Technology Developed by OSU

•Background of the Study

•Components of the Algorithm

•Methodology

•Results

•Conclusion

Need to Improve NUE

•Cereal grain NUE averages only 33% worldwide

•Rise in the price of fuel and N fertilizer

•Increase environmental risk

Applications

Success of the Technology

A 15 % increase in wheat NUE was achieved compared with conventional methods (OSU 2002, Agronomy Journal 94:815).

Yield Potential Equation

800-1000 GDD

y = 0.8855e2802.3x

R2 = 0.75P < 0.001

YP0 = 1.161e2802.3x

0

2

4

6

8

10

12

14

16

18

20

0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012

GDD INSEY

Gra

in y

ield

(Mg

ha

-1)

Efaw , OK OFIT 05

LCB, OK OFIT 05

Perkins, OK OFIT 05

Efaw , OK OFIT 04

LCB, OK Catchup 05

Efaw , OK Catchup 05

Haskell, OK Catchup 05

LCB, OK Nrate 05

Haskell, OK Nrate 05

LCB, OK Regional 05

Haskell, OK YP0 03

LCB, OK YP0 03

Haskell, OK YP0 04

LCB, OK YP0 04

By row 04

LCB, OK YP0 02

(Teal et al., 2006)

Algorithm Components

•YP0 Estimates of corn grain yield potential using NDVI and cumulative GDD

•RI N Responsiveness estimated using NDVI in the N Rich Strip and NDVI in the farmer practice or check

•CV Coefficient of variation determined from NDVI sensor readings collected in each plot

Nitrogen Fertilization Optimization Algorithm (NFOA)

Components of Algorithm

•YPN = (YP0*RI)

•N Rate =

FactorEfficiency

NuptakeNuptake YPYPN )( 0

•YP0 does not rely on historical data but rather is a simple predictive model. This approach uses seasonally dependent data capable of predicting differing yield potentials and adjusting N rates accordingly.

•YP0 changes every year as does RI.

Capability of Algorithm

YP0 and RI are independent of one another (on-farm trials 2002-2005)

0

10

20

30

40

50

60

70

1 1.2 1.4 1.6 1.8 2 2.2 2.4

Response Index

N R

eco

mm

end

ed

On Farm Trials

C Mack y = -0.0572x + 30.13

R2 = 0.0078

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60 70

N Recommended

Yie

ld o

f C

hec

k, b

u/a

c

Spatial variability can be masked bylarger plants

NDVI= 0.60NDVI= 0.60

Do these areas have the same yield potential?

CV= 23 CV= 10

RICV-NFOA

Gra

in Y

ield

INSEY INSEY

YP0 YP0

RI-NFOA RICV-NFOA

YPmax

RI-NFOA and RICV-NFOA

YPN YPN

RI = 2.0

RI = 2.0

CV

RI = 2

.0

RI = 2

.0

RI = 1

.5

RI = 1

.5

CV

Description of NFOA

•RI-NFOA – consists of YP0 and RI

YPN = YP0*RI

•RICV-NFOA – consists of YP0, RI and CV

)(*)*0(CRITICALCAP

CAPMAX CVCV

CVCVRIYPYPNY

New CV Algorithm, docking for CV>20

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 0.002 0.004 0.006 0.008 0.01

INSEY

Gra

in y

ield

, kg

/ha

0

10

20

30

40

50

60

70

80

90

100

N R

ate,

kg

/ha

YPN-CV

YP0

YPN old

N Rate CV

N Rate-RI

Objectives

•To evaluate different nitrogen fertilization optimization algorithms for prescribing mid-season fertilizer N.

•To determine the optimum resolution for treating spatial variability in corn.

Methodology

•Established in 2004 at 3 sites (1-irrigated, 2-rainfed system) in Oklahoma.

•Employed RCB Design with 3 replications

Treatment StructureTRT

Preplant N kg ha-1

Mid-Season Topdress Rate kg ha-1

Resolution m2

1 0 0 -

2 0 67 -

3 0 134 -

4 67 67 -

5 67 0 -

6 134 0 -

7 0 RICV- NFOA 0.34

8 67 RICV-NFOA 0.34

9 0 Flat RICV-NFOA -

10 67 Flat RICV-NFOA -

11 67 RICV-NFOA 2.32

12 0 RI-NFOA 0.34

13 67 RI-NFOA 0.34

Results

Treatment Preplant

kg ha-1

Topdresskg ha-1

Grain YieldMg ha-1

Nitrogen Use Efficiency

%

2004 2005 2006 2004 2005 2006 2004 2005 2006

Check 0 0 0 0 9.5 6.2 5.6 - - -

Common Flat Rate

67 67 67 67 13.4 10.3 9.6 48 57 38

67-RICV 67 25 127 52 13.9 12.0 11.1 31 52 57

67-RICV flat 67 25 127 52 13.3 11.5 10.3 35 49 48

67-RI 67 13 66 24 14.0 12.4 11.9 77 74 79

Common Flat Rate versus Algorithms at Efaw site from 2004-2006

With Preplant Nitrogen

Results

Treatment Topdresskg ha-1

Grain YieldMg ha-1

Nitrogen Use Efficiency

%

2004 2005 2006 2004 2005 2006 2004 2005 2006

Check 0 0 0 9.5 6.2 5.6 - - -

Common Flat Rate

67 67 67 13.1 9.9 9.4 71 69 73

Common Flat Rate

134 134 134 11.8 10.2 8.8 35 44 34

0-RICV 59 100 58 11.2 8.6 6.9 32 50 37

0-RICV flat 59 100 58 13.5 9.4 9.1 50 51 67

0-RI 17 66 48 12.9 10.1 9.2 79 73 83

Common Flat Rates versus Algorithms at Efaw site from 2004-2006

Without Preplant Nitrogen

Results

Algorithm Resolution

m2Total N Applied

Kg ha-1Grain Yield

Mg ha-1

Nitrogen Use Efficiency

%

2004 2005 2006 2004 2005 2006 2004 2005 2006

Check - 0 0 0 9.5 6.2 5.6 - - -

RICV-NFOA 0.34 25 127 52 13.9 12.0 11.1 31 52 57

RICV-NFOA flat 25 127 52 13.3 11.5 10.3 35 49 48

RICV-NFOA 2.32 25 132 56 13.3 11.4 10.1 35 46 54

RI-NFOA 0.34 13 66 24 14.0 12.4 11.9 77 74 79

RICV- versus RI-NFOA at Efaw from 2004-2006.With Preplant N

Results

TRT

Description Total N Appliedkg ha-1

Grain YieldMg ha-1

NUE, %

1 Check 0 5.5 -

2 *CFR-topdress 67 8.2 59

3 *CFR-topdress 134 8.5 40

4 *CFR-split 134 9.3 48

5 *CFR-preplant 67 8.0 56

6 *CFR-preplant 134 9.1 44

7 RICV-NFOA 66 7.5 49

8 RICV-NFOA 131 9.1 43

9 Flat RICV-NFOA 66 7.8 51

10 Flat RICV-NFOA 131 8.9 42

11 RICV-NFOA-2.32 133 8.8 46

12 RI-NFOA 61 8.3 63

13 RI-NFOA 119 9.6 56

On-average

* CFR : Common Flat Rate

Summary

•NUE was generally higher when mid-season N rates were generated by NFOA compared with flat farmer rates.

•Increased NUE was attributed to the lower N rates applied.

Summary

•Use of RI NFOA resulted in a higher increase in NUE than RICV NFOA.

•There was limited benefit of treating spatial variability at the high resolution (0.34 m2, RICV algorithm).

•NFOA approaches didn’t project high N rates that did not affect increased yields.

Conclusions

•Functional N rate algorithm developed for corn can increase NUE.

•Applications- Sensor Based N Rate

Calculator- Variable Rate Technology

(0.4m2)

THANK YOU!

www.nue.okstate.eduwww.nue.okstate.edu