Replacing SOIL TESTING. In-Season Soil Testing z Use of an in-season soil test for N availability in...

Replacing SOIL TESTINGReplacing SOIL TESTING

In-Season Soil TestingIn-Season Soil TestingUse of an in-season soil test for N availability in corn

PSNT (0-30cm), Magdoff et al. (1984).Separating nitrate test calibration data based on yield

potential of soils may improve PSNT and PPNT for making N recommendations in corn, when NO3 test values are in the N responsive region (Bundy and Andraski, 1995)

No soil test accurately predicted either relative grain yield or N-supplying capacity (Fox et al., 1993).

Relative grain yield vs PSNT relationship was better with NO3 and NH4 than with NO3 alone (Meisinger et al., 1992)

Use of an in-season soil test for N availability in corn PSNT (0-30cm), Magdoff et al. (1984).

Separating nitrate test calibration data based on yield potential of soils may improve PSNT and PPNT for making N recommendations in corn, when NO3 test values are in the N responsive region (Bundy and Andraski, 1995)

No soil test accurately predicted either relative grain yield or N-supplying capacity (Fox et al., 1993).

Relative grain yield vs PSNT relationship was better with NO3 and NH4 than with NO3 alone (Meisinger et al., 1992)

Sufficiency

Levels of available nutrients range in a group of soils from insufficient to sufficient for optimum plant growth

Amounts of nutrients removed by suitable extractants will be inversely proportional to yield increases from added nutrients

Calibrations have been made for changing the levels of available nutrients in the soil by adding fertilizer

Levels of available nutrients range in a group of soils from insufficient to sufficient for optimum plant growth

Amounts of nutrients removed by suitable extractants will be inversely proportional to yield increases from added nutrients

Calibrations have been made for changing the levels of available nutrients in the soil by adding fertilizer

Mobile Nutrient Yield Goal (Risk assessment of

the environment)

Immobile Nutrient Sufficiency Level (Independent

of Environment, % of Maximum yield)

Mobile Nutrient Yield Goal (Risk assessment of

the environment)

Immobile Nutrient Sufficiency Level (Independent

of Environment, % of Maximum yield)

Root Surface Sorption ZoneRoot Surface Sorption Zone

• Response does not depend on reservoir Response does not depend on reservoir • Indicator of availabilityIndicator of availability• Independent of environmentIndependent of environment

• Response does not depend on reservoir Response does not depend on reservoir • Indicator of availabilityIndicator of availability• Independent of environmentIndependent of environment

• Response depends on reservoirResponse depends on reservoir• Indicator of total availableIndicator of total available• Dependent on environmentDependent on environment

• Response depends on reservoirResponse depends on reservoir• Indicator of total availableIndicator of total available• Dependent on environmentDependent on environment

Root System Sorption ZoneRoot System Sorption Zone

•Depends on Growth StageDepends on Growth Stage •IndicatorsIndicators

•BiomassBiomass•ColorColor•ConcentrationConcentration

•Depends on Growth StageDepends on Growth Stage •IndicatorsIndicators

•BiomassBiomass•ColorColor•ConcentrationConcentration

•Independent of Growth Independent of Growth StageStage

•IndicatorsIndicators•BiomassBiomass•ColorColor

•Independent of Growth Independent of Growth StageStage

•IndicatorsIndicators•BiomassBiomass•ColorColor

NONO33-- HH22POPO44

--

Bray’s Mobility ConceptBray’s Mobility Concept

HPOHPO44==

Sensor ViewSensor ViewSensor ViewSensor View

Soil TestSoil Test

Mobile NutrientsMobile NutrientsMobile NutrientsMobile Nutrients Immobile NutrientsImmobile NutrientsImmobile NutrientsImmobile Nutrients

SensorSensor

Present N RecommendationFertilizer N = yield goal (bu/ac)*2 - soil

test NO3-N

Future N RecommendationEstimated topdress N = f (yield

potential and total N uptake, estimated using indirect measures)

Present N RecommendationFertilizer N = yield goal (bu/ac)*2 - soil

test NO3-N

Future N RecommendationEstimated topdress N = f (yield

potential and total N uptake, estimated using indirect measures)

Could we establish a sufficiency level(by growth stage, variety, etc) at

Feekes 5?

NDVI N UptakeSuff. N Rec0.3 35 40 Yld goal*1.50.5 45 60 Yld goal*1.00.7 55 80 Yld goal*0.70.9 65 100 Yld goal*0.2

Could we establish a sufficiency level(by growth stage, variety, etc) at

Feekes 5?

NDVI N UptakeSuff. N Rec0.3 35 40 Yld goal*1.50.5 45 60 Yld goal*1.00.7 55 80 Yld goal*0.70.9 65 100 Yld goal*0.2

Sunlight reachingearthSunlight reachingearth

Chlorophyll bChlorophyll b

B-CaroteneB-Carotene

PhycoerythrinPhycoerythrin

PhycocyaninPhycocyanin

Chlorophyll aChlorophyll a

300 400 500 600 700 800300 400 500 600 700 800

Wavelength, nmWavelength, nm

Ab

sorp

tio

nA

bso

rpti

on

SPAD 501, 502(430, 750)SPAD 501, 502(430, 750)

Absorption of Visible Lightby Photopigments

Absorption of Visible Lightby Photopigments

CAUSE/EFFECTCAUSE/EFFECT

Soil testing vs. Sensor based systems for developing nutrient recommendations

Soil Testing Sensor Based Analyses Detection Plant available Plant statusSample collection >20 hectares 1m2

Sampling soil, destructive plant, non-destructiveMethod Extraction & chemical Spectral radiance,

analyses wavelength specificAnalytical parameter Nutrient element Spectral radianceInterpretation Calibration with yield Calibration with yieldFertilizer Rec. Procedure specific Wavelength/index specific

Interfering Factors Affecting Fertilizer RecommendationNumber of samples (reliability)Subsoil N availability -- Weeds- Clouds- Time of day (sun angle)- Variety- Stage of growth (% cover)- Living vs. dead plant tissueField element size Field element sizeCalibration curve Calibration curve

Soil testing vs. Sensor based systems for developing nutrient recommendations

Soil Testing Sensor Based Analyses Detection Plant available Plant statusSample collection >20 hectares 1m2

Sampling soil, destructive plant, non-destructiveMethod Extraction & chemical Spectral radiance,

analyses wavelength specificAnalytical parameter Nutrient element Spectral radianceInterpretation Calibration with yield Calibration with yieldFertilizer Rec. Procedure specific Wavelength/index specific

Interfering Factors Affecting Fertilizer RecommendationNumber of samples (reliability)Subsoil N availability -- Weeds- Clouds- Time of day (sun angle)- Variety- Stage of growth (% cover)- Living vs. dead plant tissueField element size Field element sizeCalibration curve Calibration curve

Evolution of a soil testEvolution of a soil test

Evolution of a spectral testEvolution of a spectral test

Extraction Correlation Calibration On-farm Suff.Procedure with field of rates at validation Index

response a given soiltest level

Wavelength Correlation Calibration On-farm Suff./Index/band with field of rates at validation Index

response a given ___ env. spec.

Extraction Correlation Calibration On-farm Suff.Procedure with field of rates at validation Index

response a given soiltest level

Wavelength Correlation Calibration On-farm Suff./Index/band with field of rates at validation Index

response a given ___ env. spec.

NDVINDVIStrengthsSensitive to canopy cover in sparse canopiesExcellent predictor of total N uptake (vegetative stages)Amount of variability in N uptake explained by NDVI increases with advancing growth stage (% coverage)Good predictor of N uptake following freeze damagePrairie biomass (fuel load)Foliage surface area (pine)N fertilization need in maize (pre-flowering) 1996 Agron. J.Area affected by forest firesWeaknessesNot sensitive to canopy cover in dense canopies (2D not 3D)Not a good predictor of N concentration

StrengthsSensitive to canopy cover in sparse canopiesExcellent predictor of total N uptake (vegetative stages)Amount of variability in N uptake explained by NDVI increases with advancing growth stage (% coverage)Good predictor of N uptake following freeze damagePrairie biomass (fuel load)Foliage surface area (pine)N fertilization need in maize (pre-flowering) 1996 Agron. J.Area affected by forest firesWeaknessesNot sensitive to canopy cover in dense canopies (2D not 3D)Not a good predictor of N concentration

IndicesIndicesLandsat Satellite Thermic Mapper (TM) mid and near

infrared indices plant density, drought, tillage

SR (simple ratio)=NIR/redNDVI (normalized difference vegetation index) = (NIR-

red)/(NIR+red) biomass, forage N uptake, water stress, leaf area index

G-NDVI = (NIR-green)/(NIR+green)

STVI (stress related vegetation index)MPDI (microwave polarization difference index)NPCI (normalized pigment chlorophyll ratio index)

=(R680-R430)/(R680+R430)

Landsat Satellite Thermic Mapper (TM) mid and near infrared indices plant density, drought, tillage

SR (simple ratio)=NIR/redNDVI (normalized difference vegetation index) = (NIR-

red)/(NIR+red) biomass, forage N uptake, water stress, leaf area index

G-NDVI = (NIR-green)/(NIR+green)

STVI (stress related vegetation index)MPDI (microwave polarization difference index)NPCI (normalized pigment chlorophyll ratio index)

=(R680-R430)/(R680+R430)

IndicesIndices

WBI (water band index) = R970-R900PRI (physiological reflectance index)

= (R550-R530)/(R550+R530) ‘narrow waveband spectral measurements’ (sunflower)

chlorophyll, net CO2 uptake, water potential, light use efficiency

WBI (water band index) = R970-R900PRI (physiological reflectance index)

= (R550-R530)/(R550+R530) ‘narrow waveband spectral measurements’ (sunflower)

chlorophyll, net CO2 uptake, water potential, light use efficiency

What should we learn from soil testing?What should we learn from soil testing?

Process of eliminationJustus von Leibig (1803-1873) Leibig’s Law of the Minimum; nutrient

present in the least relative amount is the limiting nutrient for plant growth

all other nutrients present in excess until the deficient or limiting nutrient was in adequate supply

Father of ‘soil testing’

Process of eliminationJustus von Leibig (1803-1873) Leibig’s Law of the Minimum; nutrient

present in the least relative amount is the limiting nutrient for plant growth

all other nutrients present in excess until the deficient or limiting nutrient was in adequate supply

Father of ‘soil testing’

Liebig HyperlinkLiebig Hyperlink

http://www.treasure-troves.com/bios/Pasteur.html

Fact Sheet 2225Fact Sheet 2225

Crop small grains, sorghum, corn, cotton, cool

season grasses, weeping lovegrass, bluestem, bermudagrass, forage sorghum or corn silage, small grains for grazing, legumes in pasture, native meadows, alfalfa, peanuts, soybeans, mungbeans, cowpeas

N, P, K, S, Ca, Mg, Zn, Fe, Mn, Cu, BpH/buffer index (lime)

Crop small grains, sorghum, corn, cotton, cool

season grasses, weeping lovegrass, bluestem, bermudagrass, forage sorghum or corn silage, small grains for grazing, legumes in pasture, native meadows, alfalfa, peanuts, soybeans, mungbeans, cowpeas

N, P, K, S, Ca, Mg, Zn, Fe, Mn, Cu, BpH/buffer index (lime)

Could N uptake be used as an indicatorof yield potential when other variables are controlling response?

Should we develop technologies that treat variable ‘yield potential’

What influences NDVI?How can I use the NDVI measurement from last year, this year?

Soil Testing: Method of Extraction

Could N uptake be used as an indicatorof yield potential when other variables are controlling response?

Should we develop technologies that treat variable ‘yield potential’

What influences NDVI?How can I use the NDVI measurement from last year, this year?

Soil Testing: Method of Extraction

PhosphorusPhosphorus Fluoresce= reemit light energy absorbed as light but of a

longer wavelength and of lower energy Fluorescence spectrum is characteristic of the pigment,

so it is possible to tell which pigment is fluorescing (which one was activated)

Low P nutrition results in increased chlorophyll fluorescence, reduced photosynthetic rate, increased starch and sucrose in leaves

If the reactions of photosynthesis are blocked (chemical, cold, etc.) fluorescence will occur in-vivo because the energy absorbed cannot be used.

x-ray fluorescence (total P in plants) Time required to induce/measure fluorescence (1-2 min)

Xanthophyll

Fluoresce= reemit light energy absorbed as light but of a longer wavelength and of lower energy

Fluorescence spectrum is characteristic of the pigment, so it is possible to tell which pigment is fluorescing (which one was activated)

Low P nutrition results in increased chlorophyll fluorescence, reduced photosynthetic rate, increased starch and sucrose in leaves

If the reactions of photosynthesis are blocked (chemical, cold, etc.) fluorescence will occur in-vivo because the energy absorbed cannot be used.

x-ray fluorescence (total P in plants) Time required to induce/measure fluorescence (1-2 min)

Xanthophyll

Subsoil nutrient availabilitySubsoil nutrient availability

Can sensor based technologies assess subsurface nutrient availability? Sensing with time (Stage of growth)

could provide an indicator of subsurface nutrient availability

Can sensor based technologies assess subsurface nutrient availability? Sensing with time (Stage of growth)

could provide an indicator of subsurface nutrient availability

T1 T2 T3 T4T1 T2 T3 T4

VISIBLE Color AbsorbedVISIBLE Color Absorbed

VISIBLE Color TransmittedVISIBLE Color TransmittedVISIBLE Color TransmittedVISIBLE Color Transmitted

VioletViolet BlueBlue GreenGreen YellowYellow Orange Orange RedRedVioletViolet BlueBlue GreenGreen YellowYellow Orange Orange RedRed

Short wavelengthShort wavelengthHigh frequencyHigh frequencyHigh energyHigh energy

Long wavelengthLong wavelengthLow frequencyLow frequencyLow energyLow energy

0.010.01 1010 380380 450450 495495 570570 590590 620620 750750 1x101x1066 1x101x101111

wavelength, nmwavelength, nm0.010.01 1010 380380 450450 495495 570570 590590 620620 750750 1x101x1066 1x101x101111

wavelength, nmwavelength, nm

Gam

ma

Ray

sG

amm

a R

ays

Gam

ma

Ray

sG

amm

a R

ays

X-R

ays

X-R

ays

X-R

ays

X-R

ays

Ult

ravi

ole

tU

ltra

vio

let

Ult

ravi

ole

tU

ltra

vio

let

Infr

ared

Infr

ared

Infr

ared

Infr

ared

Mic

row

aves

an

d s

ho

rt r

adio

Mic

row

aves

an

d s

ho

rt r

adio

Mic

row

aves

an

d s

ho

rt r

adio

Mic

row

aves

an

d s

ho

rt r

adio

Rad

io, F

M, T

VR

adio

, FM

, TV

Rad

io, F

M, T

VR

adio

, FM

, TV

ElectronicElectronic VibrationalVibrational RotationalRotationaltransitionstransitions transitionstransitions transitionstransitionsElectronicElectronic VibrationalVibrational RotationalRotationaltransitionstransitions transitionstransitions transitionstransitions

Yellow-greenYellow-green YellowYellow VioletViolet BlueBlue Green-blueGreen-blue Blue-greenBlue-green

Models for Interpretation of ResponseModels for Interpretation of Response

LinearLinear-plateauQuadraticSquare rootQuadratic-plateauCate-Nelson

LinearLinear-plateauQuadraticSquare rootQuadratic-plateauCate-Nelson

20 mpg20 mpg 400 miles400 miles

Gallons

20

35

Gallons

20

3510 mpg10 mpg 350 miles350 miles

40 30 60 20

40 30 60 20

YIELD POTENTIAL

“TRIP DISTANCE”

YIELD POTENTIAL

“TRIP DISTANCE”

N FERTILIZER NEEDN FERTILIZER NEED

YP0 = 100 bushelsYPN = 140 bushels (RI of 1.4)Grain N Uptake based on YPN of 140 bu/ac = 140 bu/ac * 56 lb/bu * 1.18%N = 92.5 lb

Have 60 kg N in the plant

YP0 = 100 bushelsYPN = 140 bushels (RI of 1.4)Grain N Uptake based on YPN of 140 bu/ac = 140 bu/ac * 56 lb/bu * 1.18%N = 92.5 lb

Have 60 kg N in the plant

Need = (92.5-60)/0.7 = 46.4Need = (92.5-60)/0.7 = 46.4

Crop Production Travel Planning

Yield Potential (YP0) Trip Distance

Yield Potential with Trip Distance (adj.)added N (YPN)

Forage N Uptake Amount of Gas in TankGrain N Uptake (YPN) Total Gallons Needed

Fertilizer Need Total Gallons-Amt in Tank

Topdress N rate range Fuel efficiency

(rainfall, temp (windspeed, frost, plant stand, direction, road weed population) conditions, uphill, downhill, etc.)

Crop Production Travel Planning

Yield Potential (YP0) Trip Distance

Yield Potential with Trip Distance (adj.)added N (YPN)

Forage N Uptake Amount of Gas in TankGrain N Uptake (YPN) Total Gallons Needed

Fertilizer Need Total Gallons-Amt in Tank

Topdress N rate range Fuel efficiency

(rainfall, temp (windspeed, frost, plant stand, direction, road weed population) conditions, uphill, downhill, etc.)

Interfering agronomic factorsInterfering agronomic factors Moisture availability (texture, water holding

capacity) Nutrient(s) deficiency(ies) and/or toxicity(ies)

interactions Crop Variety within crop Preplant N rate Production system (forage vs. grain) Tillage (background) Weed interference Row spacing (coverage, plant density) Resolution to be treated (field element size)

cost of misapplication (economic vs. environment)

Moisture availability (texture, water holding capacity)

Nutrient(s) deficiency(ies) and/or toxicity(ies) interactions

Crop Variety within crop Preplant N rate Production system (forage vs. grain) Tillage (background) Weed interference Row spacing (coverage, plant density) Resolution to be treated (field element size)

cost of misapplication (economic vs. environment)

Hennessey, Feekes 4, 5 and 7Hennessey, Feekes 4, 5 and 7Hennessey, Feekes 4, 5 and 7Hennessey, Feekes 4, 5 and 7

Feekes Growth Stage 7Feekes Growth Stage 7Feekes Growth Stage 7Feekes Growth Stage 7y = 234.78x - 9.4074y = 234.78x - 9.4074y = 234.78x - 9.4074y = 234.78x - 9.4074

RRRR2222 = 0.7286= 0.7286 = 0.7286= 0.7286

0000

50505050

100100100100

150150150150

200200200200

250250250250

0000 0.20.20.20.2 0.40.40.40.4 0.60.60.60.6 0.80.80.80.8

NDVINDVINDVINDVI

To

tal

N U

pta

ke,

kg/h

aT

ota

l N

Up

take

, kg

/ha

To

tal

N U

pta

ke,

kg/h

aT

ota

l N

Up

take

, kg

/ha


RRRR2222

= 0.6687= 0.6687 = 0.6687= 0.6687


RRRR2222 = 0.3588= 0.3588 = 0.3588= 0.3588

00

1010

2020

3030

4040

5050

6060

7070

0-10

0-10

10-2

010

-20

20-3

020

-30

30-4

030

-40

40-5

040

-50

50-6

050

-60

60-7

060

-70

70-8

070

-80

8080

N rate, kg/haN rate, kg/ha

Fre

qu

en

cyF

req

ue

ncy

Frequency Distribution of VariableNitrogen Rates (4, 1x42m transects)Frequency Distribution of Variable

Nitrogen Rates (4, 1x42m transects)

8080

00

NDVINDVI

0.3 0.4 0.5 0.6 0.7 0.8 0.3 0.4 0.5 0.6 0.7 0.8 0.90.9

Max. N Rate Max. N Rate determined determined by farmerby farmer

Treatment Treatment Number of Resolution Subplots

1 0.84 m2 642 3.34 m2 163 13.38 m2 44 53.51 m2 1

Treatment Treatment Number of Resolution Subplots

1 0.84 m2 642 3.34 m2 163 13.38 m2 44 53.51 m2 1

RESOLUTION STUDYTreatment StructureRESOLUTION STUDYTreatment Structure

Contour map of NDVI values at Tipton, OK

01 02 03 04

08 07 06 05

09 10 11 12

16 15 14 13

01 02

04 03

01 01 02 03 04

08 07 06 05

09 10 11 12

16 15 14 13

01 02 03 04

08 07 06 05

09 10 11 12

16 15 14 13

01 02 03 04 05 06 07 08

16 15 14 13 12 11 10 09

17 18 19 20 21 22 23 24

32 31 30 29 28 27 26 25

33 34 35 36 37 38 39 40

48 47 46 45 44 43 42 41

49 50 51 52 53 54 55 56

64 63 62 61 60 59 58 57

01

01 02 03 04 05 06 07 08

16 15 14 13 12 11 10 09

17 18 19 20 21 22 23 24

32 31 30 29 28 27 26 25

33 34 35 36 37 38 39 40

48 47 46 45 44 43 42 41

49 50 51 52 53 54 55 56

64 63 62 61 60 59 58 57

01 01 02 03 04 05 06 07 08

16 15 14 13 12 11 10 09

17 18 19 20 21 22 23 24

32 31 30 29 28 27 26 25

33 34 35 36 37 38 39 40

48 47 46 45 44 43 42 41

49 50 51 52 53 54 55 56

64 63 62 61 60 59 58 57

01 04

02 03

01 04

02 03

NDVI

0.48

0.450.420.39

0.360.330.30

0.27

0.240.210.18

00

55

1010

1515

2020

2525

3030

0.260.26 0.

30.3

0.340.34

0.380.38

0.420.42

0.460.46 0.

50.5

0.540.54

0.580.58

0.620.62

0.660.66 0.

70.7

0.740.74

0.780.78

NDVINDVI

Fre

qu

ency

Fre

qu

ency

Distribution of NDVI values, Tipton, OKDistribution of NDVI values, Tipton, OK

Percent Coverage35 55 85

NDVI0.3 0.5 0.7


NDVI0.3 0.5 0.7

Tipton, January 15, 1998, Feekes 5Tipton, January 15, 1998, Feekes 5

Fertilizer N RateFertilizer N Rate


NDVI0.3 0.5 0.7


NDVI0.3 0.5 0.7

Tipton, January 15, 1998, Feekes 5Tipton, January 15, 1998, Feekes 5

Res. N Rate SD Yield SD Efficiency SD N Uptake SDm2 kg/ha kg/ha of Use** kg/ha____ ___________ _________ ____________ ___________0.84 56.95 19.04 2323 162 44.25 15.65 51.53 1.883.34 74.17 18.43 2329 382 33.47 12.52 52.30 5.8113.38 69.28 23.13 2473 233 38.77 13.79 54.21 4.6753.51 73.93 25.26 2555 266 37.58 13.95 60.27 6.63SED 13.97 127 7.28 3.22

** Moll et al., 1982

Res. N Rate SD Yield SD Efficiency SD N Uptake SDm2 kg/ha kg/ha of Use** kg/ha____ ___________ _________ ____________ ___________0.84 56.95 19.04 2323 162 44.25 15.65 51.53 1.883.34 74.17 18.43 2329 382 33.47 12.52 52.30 5.8113.38 69.28 23.13 2473 233 38.77 13.79 54.21 4.6753.51 73.93 25.26 2555 266 37.58 13.95 60.27 6.63SED 13.97 127 7.28 3.22

** Moll et al., 1982

Location: Perkins, 1997-98Location: Perkins, 1997-98

Sensor assemblySensor assemblySensor assemblySensor assembly

Sensed areaSensed area(treated area)(treated area)Sensed areaSensed area(treated area)(treated area)

Variable rateVariable ratespray nozzlespray nozzleVariable rateVariable ratespray nozzlespray nozzle

Spectral radiance (250-830 nm) collected from individual plots, Spectral radiance (250-830 nm) collected from individual plots,

NxP bermudagrass experiment, Burneyville, OKNxP bermudagrass experiment, Burneyville, OK

00

0.050.05

0.10.1

0.150.15

0.20.2

0.250.25

250250 350350 450450 550550 650650 750750 850850


Sp

ectr

al r

adia

nce

, %

Sp

ectr

al r

adia

nce

, %

N0 P0N0 P0N0 P60N0 P60N0 P120N0 P120N100 P0N100 P0N100 P60N100 P60N100 P120N100 P120N200 P0N200 P0N200 P60N200 P60N200 P120N200 P120N300 P0N300 P0N300 P60N300 P60N300 P120N300 P120

RedRedRedRed

NIRNIRNIRNIR

GreenGreenGreenGreen

Hasil SembiringOSU Soil FertilityHasil SembiringOSU Soil Fertility

11 55 88 66 1111 44 22 33 99 77 1212 1010

33 44 1212 1010 88 77 55 11 99 22 1111 66

88 33 77 55 11 1212 1111 44 66 22 99 1010

Trt N rate P rate1 0 02 40 03 80 04 120 05 0 106 40 107 80 108 120 109 0 2010 40 2011 80 2012 120 20

Trt N rate P rate1 0 02 40 03 80 04 120 05 0 106 40 107 80 108 120 109 0 2010 40 2011 80 2012 120 20

10 ft10 ft

30 ft30 ft

Source of variation df P Nw919 w791

Total (r*N*P)-1 35 - -Rep 2 ns nsN Rate 3 ns **P Rate 2 ** nsN Rate * P Rate 6 ns nsError 22 - -

Source of variation df P Nw919 w791

Total (r*N*P)-1 35 - -Rep 2 ns nsN Rate 3 ns **P Rate 2 ** nsN Rate * P Rate 6 ns nsError 22 - -

0 40 80 1200 40 80 120

50403020100

50403020100

00

0.050.05

0.10.1

0.150.15

0.20.2

0.250.25

0.30.3

276

276

335

335

395

395

455

455

515

515

575

575

635

635

695

695

755

755

815

815

N0 P0N0 P0

N0 P60N0 P60N0 P120N0 P120

00

0.050.05

0.10.1

0.150.15

0.20.2

0.250.25

0.30.3

276

276

335

335

395

395

455

455

515

515

575

575

635

635

695

695

755

755

815

815

N300 P0N300 P0

N300 P60N300 P60

N300 P120N300 P120


Sp

ectr

al r

adia

nc

e, %

Sp

ectr

al r

adia

nc

e, %


Wavelength IDWavelength IDWavelength IDWavelength ID


404 414 425 - - 584 735 775 785N 0.02 0.04 . . . - 0.01 0.01 0.01P . . . . . 0.18 - 0.04 0.03NP . . . . . - 0.01 0.02 0.02

404 414 425 - - 584 735 775 785N 0.02 0.04 . . . - 0.01 0.01 0.01P . . . . . 0.18 - 0.04 0.03NP . . . . . - 0.01 0.02 0.02

3.33.3

3.353.35

3.43.4

3.453.45

3.53.5

3.553.55

3.63.6

3.653.65

3.73.7

00 5050 100100 150150 200200 250250 300300N RateN Rate

w73

5/w

534

w73

5/w

534

60300

60300

Replacing SOIL TESTING. In-Season Soil Testing z Use of an in-season soil test for N availability in...

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