Louisiana State University Sensor Research Updates

Yumiko Kanke, Dr. Brenda Tubana, Dr. Jasper Teboh, and Josh Lofton

Remote Sensor Studies• Crops: sugarcane, rice, cotton and corn• Application: improve midseason N fertilizer

recommendations• Activities

– Update database– Refinement algorithms – Validation/calibration

• Grain yield potential can be predicted at panicle differentiation (1501-1900 cumulative GDD).

• Research in on-going – To evaluate the impact of water reflectance– To refine the algorithm

Rice Updates

• The water as a background may alter canopy reflectance readings. This is most significant when plant biomass is small and the stand is thin.

– Low N rate, NDVI could be from 0.44 to 0.58 – High N rate, NDVI could be from 0.62 to 0.66

Rice Updates

Check Plot

NDVI =0.168

0.438

Nadir

Tilted (45o angle)

210 lbs/A

0.725

0.757

Rice Updates

Poster Presentation

Sugarcane Updates

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Opti

mum

Nitr

ogen

Rat

e, lb

s/ac

Site-Year2004 to 2009, different varieties

No response

No response

No response

No response

No response

No response

No response

No response

Recommended N for stubble cane:80-120 lbs N ac-1

Recommended N for plant cane:60-100 lbs N ac-1

Estimated optimal N rates for cane yield production fell within or below (majority of the site-years) the recommended rates . *Sugarcane is a perennial crop. Plant cane is fist year plant, stubble cane is 2nd or 3 rd year plant.

Sugarcane: Research Focus 1• Sugarcane is a perennial

crop. It re-grows after each harvest for multiple years (4 years) without annual reseeding.

• Crop age effect• Refinement procedure

– cumulative growing degree days

– Number of days from __ to sensing

cane yield potential = 11.162e1.5717*NDVI

r² = 0.4618

0

5

10

15

20

25

30

35

40

45

50

0.35 0.45 0.55 0.65 0.75 0.85

Cane

Yie

ld, t

on/a

cre

988 2nd Stubble

128 2nd Stubble

226 1st Stubble

384 1st Stubble

540 1st Stubble

226 1st Stubble

233 1st Stubble

540 1st Stubble

226 Plant Cane

233 Plant Cane

sugar yield potential = 2354.4e1.7915*NDVI

r² = 0.5012

0

2000

4000

6000

8000

10000

12000

0.35 0.45 0.55 0.65 0.75 0.85

NDVI

Suga

r Yie

ld, l

bs/a

cre

Sugarcane: Research Focus 2• Varietal diversification is an essential program

in Louisiana’s sugarcane industry.• Canopy structure effect• Refinement procedure -categorize by canopy structure (droopy and erect leaf) or plant height

• Categorize by canopy structure (droopy and erect leaves)

0.5 0.6 0.7 0.82000300040005000600070008000

f(x) = 2217.04026319 exp( 1.43269031555 x )R² = 0.227652592252352

226

0.4 0.5 0.6 0.7 0.82000300040005000600070008000

f(x) = 2277.96128129 exp( 1.51731887754 x )R² = 0.422543173896888

384

0.4 0.5 0.6 0.7 0.83000

5000

7000

9000

f(x) = 3280.48863831 exp( 1.19972951615 x )R² = 0.267239395528891

5400.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8

2000

3000

4000

5000

6000

7000

8000

9000

10000

f(x) = 2827.51262434566 exp( 1.2185661227715 x )R² = 0.206796235614498

All data

226

384

540

NDVI

Suga

r yie

ld (l

bs/a

c)

Sugarcane: Research Focus 2

Sugarcane: Research Focus 3• Nitrogen fertilization is done early in spring

(one time application)• Tall stature – challenge when collecting data• How early we can put our N reference strip?• How late can we apply N fertilizer?• Small biomass is an issue early in the spring. Three weeks after growth

recommenced in spring, height may become an issue.

• Evaluate spectral reflectance based on leaf element and plant canopy structure using red-edge.

Rice and Sugarcane: Research Focus 4

Red-edge

Wavelength between RED and NIR wavelengths 670 nm to 780 nm (Meer and Jong, 2006) 700 and 750 nm (Seager, 2005)

The first or second derivative of reflectance between 690 to 740 nm, depending on the sensor (Dixit, 1985)

Index

• Reflectance Reflectance between 680-740 nm. Index could be

described as ratio of reflectance.

• Derivative analysis (Red-edge position) The wavelength of maximum slope in the red edge

reflectance . The wavelength which has a maximum point of the first derivative reflectance. Index could be described as the specific wavelength . (Cho and Skidmore)

For example- Chlorophyll content can be explained by red-edge index

Red-Edge (Reflectance Ratio) (R734-747nm)/(R715-726nm)

Red Edge PositionThe maximum point of the first derivative reflectance

(Moss, 1991)

Derivative AnalysisNot only points but area and shape

(Filella, 1994)

High N rate Low N rate

• Maximum point – Longer wavelength (approx. 750 nm)– Peak of the reflectance pattern

• Large total area

• Maximum point-Shorter wavelength-Between 720 to 740 nm

• Small total area

• Highly correlated with - chlorophyll content (Meer, 2007)

- plant biomass (Mutanga, 2004)

• Less affected by soil background (Jong, 2007)

• Very narrow bands needed to be observed• Complicated method to determine REP -The simple maximum derivatie -Linear interpolation (Guyot and Baret, 1988) -Inverted Gaussianmodelling (Miller et al., 1990) -High orderpolynomial fitting (Pu et al., 2003) -Linear extrapolation techniques (Cho and Skidmore ) -Lagrangian interpolation technique (Dawson and Curran, 1998)

Red-Edge Points

Potential to be a new index for determine N rate?• Yes, especially biomass completely covers ground

Red650nm

NIR780nm

0 0.05 0.1 0.15 0.2 0.25 0.30

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1NDVI at Different Biomass Level

Feekes 4Feekes 5Feekes 7Feekes 10

Degree of Plant Biomass

NDVI

• However, need to be discussed - Red-edge, What are you looking for? Red-edge

reflectance, point, shape, or area? - Looking at very narrow bands, work in practical fields?

Thank you

References• Meer, F.V.D., and S.M. de Jong. 2006. Imaging spectrometry for agriculture applications. In: Imaging

spectrometry: Basic principal and prospective application, eds. Clevers, J. G. P. W. and R. Jongschaap, pp.157-197. Dordrecht, Netherlands : Springer.

• Seager, S., E.L. Turner, J. Schafer, and E.B. Ford. 2005. Vegetation’s Red edge: a possible spectroscopic biosignature of extraterrestrial plants. Astrophysics. 5: 372-390.

• Dixit, L. and S. Ram. 1985. Quantitative analysis by derivative electronic spectroscopy. Appl. Spectr. Rev. 21:311-418.

• Cho, M.A, A.K. Skidmore, C. Atzberger.. Towards red-edge positions less sensitive to canopy biophysical parameters using prospect-sailh simulated data. http://www.isprs.org/proceedings/XXXVI/part7/PDF/115.pdf

• Cho, M.A. and Skidmore, A.K., In Press. A new technique for extracting the red edge position from hyperspectral data: The linear extrapolation method. Remote Sensing of Environment.

• Guyot, G. and Baret, F., 1988. Utilisation de la haute resolution spectrale pour suivre l'etat des couverts vegetaux, Proceedings of the 4th International colloquim on spectral signatures of objects in remote sensing. ESA SP-287, Assois, France, pp. 279-286.

• Miller, J.R., Hare, E.W. and Wu, J., 1990. Quantitative characterization of the red edge reflectance. An inverted- Gaussian reflectance model. International Journal of Remote Sensing, 11(10): 1755-1773.

• Pu, R., Gong, P., Biging, G.S. and Larrieu, M.R., 2003. Extraction of red edge optical parameters from Hyperion• data for estimation of forest leaf area index. IEEE Transactions on Geoscience and Remote Sensing, 41(4): 916-

921.• Dawson, T.P. and Curran, P.J., 1998. A new technique for interpolating red edge position. International

Journal of Remote Sensing, 19(11): 2133-2139.