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Title: USING INFRARED SPECTROSCOPY (DRIFTS AND NIRS), COMBINED WITH CHEMOMETRICS, FOR THE EVALUATION OF SOIL PARTICLE SIZE DISTRIBUTION

Author
item MACHADO, P - EMBRAPA SOLOS, BRAZIL
item MADARI, B - EMBRAPA SOLOS, BRAZIL
item Reeves Iii, James
item COELHO, M - EMBRAPA SOLOS, BRAZIL
item COELHO, R - IAC-CAMPINAS
item DE-POLLI, H - EMBRAPA AGROBIOLOGIA
item GRILLO, A - PUC-RIO/EMBRAPA SOLOS

Submitted to: Brazilian Soil Science Congress
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2005
Publication Date: 8/1/2005
Citation: Machado, P.L., Madari, B.E., Reeves III, J.B., Coelho, M.R., Coelho, R.M., De-Polli, H., Grillo, A.V. 2005. Using infrared spectroscopy (drifts and nirs), combined with chemometrics, for the evaluation of soil particle size distribution. Brazilian Soil Science Congress, July 17-22, 2005, Recife-PE, Brazil. CD.

Interpretive Summary: Spectroscopy using light beyond the range of human sight has come to be used to determine the composition of a wide variety of agricultural materials and analytes. Recently efforts have been made to use the same techniques to soil composition in a rapid and relatively inexpensive manner. Although the largest interest is in rapid methods for the determination of carbon (C) in soils for the purpose of determining whether C is being sequestered or lost from soil stocks, there is also interest in determining other soil compositional parameters. The objective of this work was to test mid- and near infrared diffuse reflectance spectroscopy (DRIFTS and NIRS) for the evaluation of particle size distribution in tropical soils from the Brazilian National Soil Collection. The reference method used for calibrations was the pipette method. Two calibration data sets were defined. One with a wide range of sand and clay size particles (SAND1: 2 <= sand <= 978 and CLAY1: 10 <= clay <= 980 g kg-1), and one with narrower range (SAND2: 28 <= sand <= 460 and CLAY2: 469 <= clay <= 851 g kg-1). Results showed that DRIFTS gave calibrations of higher accuracy for both calibration sets, however the difference between DRIFTS and NIRS is more stressed, both for sand and clay, for the sample set of wider particle size distribution. Infrared spectroscopy (DRIFTS and NIRS), associated with chemometrics, is being discovered as a powerful tool for quantitative analysis of soils. Its application could be advantageous especially for the analysis of large numbers of samples as it reduces analysis time and cost. It is of great relevance to conduct studies to discover the potentials of this technique, and establish methodology and criteria for its use.

Technical Abstract: The objective of this work was to test mid- and near infrared diffuse reflectance spectroscopy (DRIFTS and NIRS) for the evaluation of particle size distribution using PLS calibration, in tropical soils from the National Soil Collection of Embrapa Solos. The reference method used for calibrations was the pipette method. Two calibration data sets were defined. One with a wide range of sand and clay size particles (SAND1: 2<= sand <= 978 and CLAY1: 10 <= clay <= 980 g kg-1), and one with narrower range (SAND2: 28 <= sand <= 460 and CLAY2: 469 <= clay <= 851 g kg-1). Results showed that DRIFTS gave calibrations of higher accuracy for both calibration sets, however the difference between DRIFTS and NIRS is more stressed, both for sand and clay, for the sample set of wider particle size distribution. Infrared spectroscopy (DRIFTS and NIRS), associated with chemometrics, is being discovered as a powerful tool for quantitative analysis of soils. Its application could be advantageous especially for the analysis of large numbers of samples as it reduces analysis time and cost. It is of great relevance to conduct studies to discover the potentials of this technique, and establish methodology and criteria for its use.