Drew Tucker and Dave MengelKSU Agronomy

An update on Kansas sensor based N

recommendations

Background: Our program was started in 2005 with a

visit to OSU.Visited Bill Raun and John Soley that summerBill gave us a GreenSeeker red handheld unit

to useHired Drew Tucker as a GRA to work on the

projectWe began taking measurements with

the GreenSeeker red sensor on an existing sorghum experiment that summer with the intent of seeing how it worked, and if it did, develop K-State N rec’s for wheat, and sorghum.

Background: We put out our first field trials in 2006:

Focus was on sorghum and wheat as those crops were where we felt we could make the greatest impact.

Purchased a Crop Circle amber sensor in 2006. Setting between OSU and UNL-ARS, we wanted

to understand the differences between the two sensors and the different approaches the two groups were taking

We wanted to determine if we needed different algorithms for different sensors.

Where we’re at todayInitial downloadable algorithms

(GreenSeeker based) were made available to the public for wheat and sorghum through the K-State Soil Testing Lab website in January 2009.

K-State algorithm options were added to the menu of the GreenSeeker control unit for wheat and sorghum for the 2009 crop year.

Corn algorithms for use at V-8/9 will be available for 2010.

General Approach

Our General Approach to Algorithms and Rate Calculators

Our approach to developing rate calculators is based on:An in-field reference strip; calculated RI;

relationship of RI at sensing to RI at harvest; expected N uptake; and NUE.

Yield potential is estimated from reference strip.

Yield response to additional N is based on the expected RI at harvest based on RI at sensing and yield potential of reference.

Additional N need to optimize yield is estimated from N uptake data across a range of yield levels,

Estimated NUE is used to covert N uptake need to fertilizer N need. Base is 50%, but can be adjusted up or down based on soils, climate or management practice.

K-State Grain Sorghum Nitrogen Rate CalculatorNDVI Reference Strip 0.6NDVI Farmer Practice 0.57Max Yield for Area bu/ac 130Days from planting to sensing where avg. temp > 63 F 35Grain Price, $/Bu 2.5Nitrogen Price, $/lb actual N 0.35Application Cost, $/Ac 5Expected Nitrogen Efficiency, % Recovery 50

Expected Response Index of Grain Yield 1.26Yield Potential of Reference Strip bu/ac 100.1Yield Potential without N bu/ac 79.6N Rec. lbs N/Ac unadjusted for G:N price ratio 39.0N rec. lbs N/Ac adjusted for G:N price ratio 40.8Gross Return (no Nitrogen) $/ac 198.94Gross Return (using N Rec) $/ac 233.34

Farmer Inputs

Outputs

Grain sorghum yield relationship used to estimate yield potential of

the field.

y = 4.9796e175.06x

R2 = 0.76

020406080

100120140160180200

0.0100 0.0120 0.0140 0.0160 0.0180 0.0200 0.0220

Gra

in Y

ield

Bu/

Acre

INSEY (NDVI/DAP)

Grain Sorghum Yields vs. NDVI 2006-2008

y = 6.3098e3.923x

R2 = 0.49

0

20

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60

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100

120

140

160

180

200

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

NDVI at GS-3

Gra

in Y

ield

Bu/

Acr

e

Grain Sorghum Yields vs. NDVI/GDU’s 2006-2008

y = 7.4016e3341.5x

R2 = 0.61

0

20

40

60

80

100

120

140

160

180

200

0.0002 0.0004 0.0006 0.0008 0.001

INSEY (NDVI/GDU's)

Gra

in Y

ield

Bu/

acre

RI at GS-3 vs. RI Grain Yield at Harvest used to calculate yield response to added N

(delta yld)

y = 0.0331e3.456x

R2 = 0.92

0

2

4

6

8

10

12

0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8RI at GS-3

RI G

rain

Yie

ld a

t Har

vest

Measuring biomass and uptake

Sorghum N Uptake (grain+stover) vs. Yield

y = 0.8327x + 11.509R2 = 0.94

0

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160

0 20 40 60 80 100 120 140 160 180

Yield bu/ac

Tota

l N U

ptak

e lb

s/ac

Example calculationReference strip NDVI = 0.60 @ 35 DAP, INSEY =

0.0171Farmer Practice NDVI = 0.57, INSEY = 0.0163

RI vegetation = 1.05, RI grain = 1.26Yield potential of fertilized reference strip, 100 bu/ac

For farmer practice without additional fertilizer, 80 bu/acCalculated from reference yield potential and RI grain

N uptake needed to gain additional 20bu yield to realize potential20 bushels x 0.95 lbs N/bu = 19 lbs N uptake per

acreAdjusted for NUE or recovery 19/0.5 = 38 lbs N

fert/ac

Grain Sorghum Nitrogen Sensor Calculator Performance 2006-2008

Location Year Sensor Yield Actual Yield Sensor Rec. Actual N Resp. Sensor DifBelleville 2006 95 96 0 0 0Manhattan 2006 160 155 33 33 0Partridge 2006 48 32 57 55 2Tribune 2006 130 128 24 15 9Manhattan 2007 111 109 98 105 -7Partridge 2007 77 70 15 20 -5Tribune 2007 71 79 0 0 0Manhattan 2008 151 128 45 45 0Ottawa 2008 58 64 55 60 -5Partridge 2008 140 123 30 15 15Mean difference 4.3

Comparison of Sensor Based N Rec’s to Soil Test Based Rec’s, 2006-2008

Location Year Sensor Yield Actual Yield Soil Test Rec. Sensor Rec. Actual N Resp. Soil Diff. Sensor Diff.Belleville 2006 95 96 40 0 0 40 0Manhattan 2006 160 155 60 33 33 27 0Partridge 2006 48 32 42 57 55 -13 2Tribune 2006 130 128 30 24 15 15 9Manhattan 2007 111 109 130 98 105 25 -7Partridge 2007 77 70 40 15 20 20 -5Tribune 2007 71 79 54 0 0 54 0Manhattan 2008 151 128 77 45 45 32 0Ottawa 2008 58 64 56 55 60 -4 -5Partridge 2008 140 123 41 30 15 26 15

GS NDVI vs. CC NDVI

y = 1.3545x - 0.1783R2 = 0.8986

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

CC NDVI

GS

ND

VI

GS RI vs. CC RI

y = 1.4428x - 0.4427R2 = 0.9096

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

0.9 0.95 1 1.05 1.1 1.15 1.2 1.25

CC RI

GS

RI

GS and CC Sensor Recommendations at 120 Bushel Yield Potential

0

20

40

60

80

100

120

140

0.9 0.95 1 1.05 1.1 1.15 1.2 1.25

RI

Sugg

este

d N-R

ate

lbs/

Ac

GS 120 Bushel

CC 120 Bushel

Winter Wheat N Rate Calculator

NDVI Reference Strip 0.6NDVI Farmer Practice 0.5Max Yield for Area bu/ac 70Days from planting to sensing where avg. temp >40 F 86Grain Price $/Bu 4.85Nitrogen Price $/lb N 0.38Application Cost $/Ac 5Nitrogen Efficiency % recovered 50

Response Index 1.20Yield Potential of Reference Strip bu/ac 64.6Yield Potential without N bu/ac 53.8N Rec. lbs N/Ac unadjusted for G:N price ratio 35.5N rec. lbs N/Ac adjusted for G:N price ratio 42.6Gross Return (no Nitrogen) $/ac 261.00Gross Return (using N Rec) $/ac 297.22

Outputs

Farmer Inputs

Winter Wheat Yield Prediction 2006-2008

y = 12.871e202.23x

R2 = 0.76

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30

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50

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70

80

90

100

0 0.002 0.004 0.006 0.008 0.01

Gra

in Y

ield

Bu/

ac

INSEY (NDVI/DAP) Feekes 4-5

Winter Wheat Nitrogen Sensor Calculator Performance 2006-2009

Location Year Sensor Yield Actual Yield Sensor Rec. Optimum N Sensor Diff.

Manhattan 2006 63 61 78 75 3Manhattan 2007 45 45 1 0 1

Johnson 2008 34 31 67 65 2Manhattan 2008 36 36 47 40 7Partridge 2008 66 69 47 44 3Johnson 2009 30 21 18 30 -12

Manhattan 2009 80 78 35 40 -5Partridge 2009 47 43 25 60 -35

-4.5Mean Difference

Issues with sensing wheatPlanting date and spring vegetation

In western KS (and I assume OK) more 2nd year and cont wheat is grown, it’s planted early, more fall-early spring growth, and the sensor can be used successfully at earlier growth stages (Feekes 3?)With the very early planting common in W Kansas

can actually use the sensor before dormancy in the fall in many fields.

In eastern Kansas, wheat is planted later (after soybeans), barely emerges prior to winter and you don’t get adequate levels of vegetation for sensing until much later in the spring (Feekes 4/5).Problem is multiplied with no-till wheat.

Future work on sorghum and wheatTesting on farmers fields to confirm the rate

calculators work in the real world.Started in 2009, but will be the primary focus

of our wheat and sorghum work in 2010.Algorithms seem to work well when little or

no N is applied at or near planting. But what about fields where 50% of the expected

need was applied preplant? Or a rescue situation where large amounts of

preplant N was lost very early?

Corn workIn 2007 we initiated a corn study

focused on using the GS and CC at the V-8/9 growth stage. This study was initiated at Rossville (NE) and Tribune (WC) under sprinkler irrigation.

In 2008 added a flood irrigated site at Colby (NW), and a high yielding dryland site at Manhattan.

Treatment Total N Applied Grain Yield Total N Uptake

  2007 2008 2007 2008 2007 2008

Starter Only 20 20 135 82 88 51

120 S+ pre 120 120 219 213 168 146

160 160 160 218 228 154 163

200 200 200 227 234 183 186

120 split 120 120 223 201 182 141

160 split 160 160 224 222 172 152

200 split 200 200 219 226 176 162

120 + GS 125 163 224 224 166 155

120 + CC 125 178 224 222 163 153

120 + Spad 130 143 215 210 167 140

GS + Spad 120 130 214 227 174 148

CC + Spad 120 175 212 230 156 166

Results from corn work at Rossville, KS 2007&8

Corn Yield Prediction 2006-2008

y = 18.312e164.78x

R2 = 0.66

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240

280

0 0.005 0.01 0.015 0.02

Corn

Gra

in Y

ield

Bu/

Ac

INSEY (NDVI/DAP) at V-8,9

Corn Sensor Based N Rate CalculatorWill be finished after this years field work is

finished.Will be similar to other calculators.Hopefully the performance will be as good

as the other two.

Additional work on cornLate season rescue N applications to corn

at V-12 to 16 using high clearance sprayers.Work started in 2009, both on research farms

and with cooperative farmers and dealers/custom applicators

Loss of preplant N, KS 2009

Denitrification N loss in corn, KS 2009

Issues with cornBiomass/sensor saturation

Purchased a Crop Circle ACS470 to look at the “red edge”

Working in the row middle to reduce biomass in the sensor footprint.

y = 1.3561x - 0.6628R2 = 0.97

y = 1.3096x - 0.6389R2 = 0.96

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.68 0.7 0.72 0.74 0.76 0.78 0.8 0.82 0.84 0.86

Red NDVI

Red

Edge

NDV

I

GS

CC

Red Edge NDVI vs. Red NDVI from GreenSeeker and Crop Circle Sensors

Estimating NUECan we estimate expected NUE/Recovery

based on soil, climate and crop-fertilizer management?

Project initiated in 2008Includes both a “data mining” and field

componentIntent is to provide quantitative estimates of

the expected NUE from different management practices as impacted by soils and climate.

Using standard practices as base and providing/developing adjustment coefficients up or down.

Questions?