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Title: Espectroscopia infravermelha para a determinacao de carbono do solo: Perspectiva de um metodo economicamente viavel e ambientalmente seguro

Author
item MADARI, BEATA - EMBRAPA RICE AND BEAN
item Reeves Iii, James
item COELHO, MAURICO - EMBRAPA SOILS
item MACHADO, PEDRO - EMBRAPA RICE AND BEAN
item DEPOLLI, HELVECIO - EMBRAPA AGROBIOLOGY
item COELHO, RICHARDO - IAC CAMPINAS
item DE MELO BENITES, VINICIUS - EMBRAPA SOILS
item DE SOUZA, LUCAS - EMBRAPA SOILS
item McCarty, Gregory

Submitted to: Popular Publication
Publication Type: Popular Publication
Publication Acceptance Date: 7/22/2007
Publication Date: 7/22/2007
Citation: Madari, B.E., Reeves III, J.B., Coelho, M.R., Machado, P.L., Depolli, H., Coelho, R.M., De Melo Benites, V., De Souza, L.F., Mccarty, G.W. 2007. Espectroscopia infravermelha para a determinacao de carbono do solo: Perspectiva de um metodo economicamente viavel e ambientalmente seguro. Web publication #126 at http://www.cnpaf.embrapa.br/publicacao/comunicadotec/.

Interpretive Summary: The Kyoto Protocol is stimulating the establishment of national soil carbon inventories and is motivating the implementation of projects that promote carbon accumulation in terrestrial ecosystems. To be able to effectively monitor such projects methods that are able to analyze vast number of samples within a reduced time period are needed. Currently standard methods of soil carbon analysis are either slow, require the use of toxic reagents (Walkley-Black method and its variations, Yeomens-Bremner method and its variations) or have accuracy problems (loss-on-ignition). Spectroscopic techniques like near-infrared reflectance spectroscopy (NIRS) and diffuse reflectance Fourier transform spectroscopy (DRIFTS), combined with chemometrics, can simultaneously determine any number of variables, including different carbon forms. The objective of this work was to show the utility of these techniques in the quantitative determination of total and organic soil carbon using a representative set of soils from Brazil. It was demonstrated that both NIRS and DRIFTS can be used even in the case of very diverse sample populations. However, depending on the level of accuracy needed, the creation of subpopulations of soil samples may be needed, based on their textural properties. Near-infrared reflectance spectroscopy could be used for less diverse sample populations, for example, where all samples belong to the very clayey textural group. Using DRIFTS more robust calibrations can be achieved and also for more diverse sample populations. Based on this, for quantitative carbon analysis in soils, DRIFTS appears to be a very promising alternative for standard carbon analysis.

Technical Abstract: The Kyoto Protocol is an agreement among many of the world’s nations to, among other things, reduce atmospheric carbon dioxide concentrations in order to reduce global warming. One potential method to do so is to sequester carbon in soils. This has had the effect of stimulating the establishment of national soil carbon inventories and is motivating the implementation of projects that promote carbon accumulation in terrestrial ecosystems (soils, trees, etc.). To be able to effectively monitor such projects methods that are able to analyze vast number of samples within a reduced time period are needed. Currently standard methods of soil carbon analysis are either slow, require the use of toxic reagents or have accuracy problems. Spectroscopic techniques like near-infrared reflectance spectroscopy (NIRS) and diffuse reflectance Fourier transform spectroscopy (DRIFTS), combined with chemometrics (mathematical methods for relating the spectral information to chemical composition), can simultaneously determine any number of variables, including different carbon forms. The objective of this work was to show the utility of these techniques in the quantitative determination of total and organic soil carbon using a representative set of soils from Brazil. It was demonstrated that both NIRS and DRIFTS can be used even in the case of very diverse sample populations. However, depending on the level of accuracy needed, the creation of subpopulations of soil samples may be needed based on their textural propertied (sand, silt and clay contents). Near-infrared reflectance spectroscopy could be used for less diverse sample populations, for example, where all samples belong to the very clayey textural group. Using DRIFTS more robust calibrations can be achieved and also for more diverse sample populations. Based on this, for quantitative carbon analysis in soils, DRIFTS appears to be a very promising alternative for standard carbon analysis.