1. Wilson Tadeu Lopes da Silva1, Débora Marcondes Bastos Pereira Milori1,
Ladislau Martin-Neto1,2, Adolpho José Posadas1,3, Aline Segnini1,3, Roberto
1
Quiroz3
1- Brazilian Agricultural Research Corporation (Embrapa) – Embrapa Agricultural
Instrumentation Center – São Carlos/SP, Brazil.
2- Virtual Laboratories of Embrapa abroad – Labex – Beltsville/MD, USA
3- International Potato Center (CIP) – Lima, Peru.
Rome – Italy
13 July 2010

2. 2
• Does the determination of Carbon content in the
soil, satisfactory for analysis of balance of carbon
in agriculture areas?
• Do the actual laboratory analyses adequate in
terms of practice, representativity, costs, etc.?

3. 3
Our proposal
•To use Fluorescence parameters to produce a
quick indicator for changes in structure of SOM;
•Measure this indicator using whole soil;
We built an apparatus to evaluate the feasibility of using laser-induced
fluorescence spectroscopy (LIFS) for whole soil analysis

4. 4
Portable Laser-Induced Fluorescence
Spectroscope
Optical Bunddle
Profile
Excitation Fibers
Emission Fiber
Laser
Miniature spectrometer
Filter
Optical bunddle
Lap-top
soil
Miniature spectrometer
Segnine, A.; Milori, D.; et al. Spectroscopic assessment of soil organic matter in wetlands from the high Andes,
accepted in Soil Science Society of America Journal

5. 5
Portable LIFS system

6. 6
Portable LIFS system

7. HLIF = Humification Index
7
Laser-Induced Fluorescence Spectroscopy
400 450 500 550 600 650 700
3
2
1
0
NATURAL SOIL
HEATED SOIL (600°C)
Intensity (a.u.)
λ (nm)
HLIF = Area
C
Milori et al.. Soil Science Society of America Journal 70 (1): 57-63 JAN-FEB 2006

8. 8
Laser-Induced Fluorescence Spectroscopy
3.0
2.5
2.0
1.5
1.0
0.5
R=0.85; P<0.0001
0.05 0.10 0.15 0.20 0.25 0.30
HLIF ( Whole Soil)
A4/A1 (HA in solution)
Milori et al.. Soil Science Society of America Journal 70 (1): 57-63 Jan-Feb 2006
Segnini, A.; Milori, D.; et al. Soil Science Society of America Journal. Acepted to be published.

9. 9
Sample preparation
soil samples from
experimental area
manual cleaning,
and after the
samples are sieved
15 ton of
pressure
3 pellets of
each sample
(1 g)
Cost equipment ~ US$ 30.000,00
Cost / Analysis : US$ 0.50

10. 10
Portable LIFS system
Advantages
- Faster and cleaner process;
- Low cost;
- It is possible a large scale measurements;
- Allow analyses of SOM near its natural state;
- Contribution of Humin is taking into account in the analyses;
- To allow evaluation of changes in SOM according to soil management.
Disadvantages
- It is not a selective technique. It is difficult to identify structures;
- Quenching effect due to interaction with metal can occur;
- For organic soils it is necessary to take care with Inner Filter Effect.

11. To quantify soil carbon in a clean and agile
way using methods economically viable
11
¾¾Determination by Near Infrared Spectroscopy (NIRS)
¾¾Texture (Sand, Clay, and Silt)
¾¾Soil organic matter
¾¾Microbial activity
¾¾Determination by Laser Induced Breakdown
Spectroscopy (LIBS)

12. 12
What is LIBS?
¾¾Laser Induced Breakdown Spectroscopy (LIBS) is an emerging
analytical technique based on atomic and ionic emission of elemental
sample constituents.
¾¾During the LIBS analytical process the sample is irradiated by a
highly energetic laser pulse and absorbs this energy. The high
temperature of ablated material generates a small plasma plume. As
result of the temperature, the ablated material breaks down into
excited ionic and atomic species.
sample
Pulsed laser
emission
Plasma

13. 13
What is LIBS?
¾¾During the plasma cooling, the excited species return to their ground
state emitting electromagnetic radiation in characteristic wavelengths.
¾¾In this sense, the analysis of sample emission spectra gives a qualitative
view of sample elemental composition.

14. 14
Soil pellet
coin

15. 15
Laser
1064 nm
LIBS apparatus
Focuses lens
Plasma
Sample
Fiber optics
spectrometer
Computer
Use of Artificial Neural Network (ANN)

16. 16
Embrapa systems
Bench Portable
Spectrometers manufactured by Ocean Optics
model LIBS2500
spectral range: 188-980 nm
Resolution: 0.1 nm
Laser manufactured by Quantel
model Big Sky Laser Ultra50
single-pulse energy 50 mJ
pulse duration 8ns
Delay time: 3 μs
Spectrometers manufactured by StellarNet Inc
model LIBS2500
spectral range: 190-1000 nm
Resolution: 0.2 nm
Laser manufactured by Kigre Inc.
model MK-367
single-pulse energy 20 mJ
pulse duration 4ns
Delay time: 2 μs

17. 17
Typical soil emission –– C region
350
300
250
200
150
100
50
0
C
Al
190 192 194 196 198 200
Intensidade (u.a.)
Comprimento de Onda (nm)
wavelength (nm)
Da Silva, R, Milori, D. et al.. Spectrochimica Acta. Part B, Atomic Spectroscopy. , v.63, p.1221 - 1224, 2008.

18. 18
LIBS + Artificial Neural Network for
Carbon analysis
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1
1,1
1,0
0,9
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0,0
C(%) LIBS/MLP
C (%) TOC
R=0.93
LOD: 0,3%
C reference
concentration
(%)
C predicted
concentration
(%)
Absolute
Error
0.51 0.43 (±0.04) -0.08
0.79 0.94 (±0.08) 0.15
0.62 0.78 (±0.15) 0.16
0.48 0.56 (±0.09) 0.08
0.65 0.76 (±0.10) 0.11
0.36 0.44 (±0.07) 0.08
0.45 0.51 (±0.07) 0.06
0.72 0.76 (±0.07) 0.04

19. 19
LIBS + ANN
0 1 2 3 4 5 6 7 8 9
250
200
150
100
50
0
Ba (mg kg-1)
Validation Samples
ICP OES
LIBS
0 1 2 3 4 5 6 7 8 9 10
100
80
60
40
20
0
Co (mg kg-1)
Validation samples
ICP OES
LIBS
0 1 2 3 4 5 6 7 8 9 10
250
200
150
100
50
0
Cu (mg kg-1)
Validation samples
ICP OES
LIBS
Co
0 1 2 3 4 5 6 7 8 9 10
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Mn (mg kg-1)
Validation samples
ICP OES
LIBS
Ba
Cu Mn

20. 20
Sample preparation
soil samples from
experimental area
manual cleaning,
and after the
samples are sieved
15 ton of
pressure
1 pellet of
each sample
(1 g)
Cost equipment ~ US$ 50.000,00
Cost / Analysis : US$ 0.50

21. 21
Soils & Humic Substances
Leader: Dr. Ladislau Martin-Neto
Research team: Débora Milori
Silvio Crestana
Wilson T. L. da Silva
Marcelo L. Simões
Carlos Vaz
Luiz A. Colnago
Ednaldo Ferreira
Adolfo Posadas
Roberto Quiroz
Pos-doc: Edilene C. Ferreira
Aline Segnini
Students
Cleber Hilário dos Santos
Bruno H. Martins
Lilian F. de Almeida
Lívia Favoretto
Mariani Mussi
Camila Carvalho
André Venâncio
Marcelo Cardinalli
Mariana Russo
Marina França-Silva
Bruna D.L. Pinto
Thais Oahshi
Lilian F. de Almeida
Tatiana M. Ferrarezi
Partnerships:

22. 22
Acknowledgements

23. 23
www.cnpdia.embrapa.br
wilson@cnpdia.embrapa.br