Espectroscopia no Infravermelho Próximo para a Quantificação de Carbono em Solos da Bacia do Acre

Abstract

In soil carbon determination various techniques are used, predominating in Brazil methods based on oxidation of organic matter in the presence of potassium dichromate in an acidic medium and the elemental analysis. The objective of this study was to evaluate the technical viability of NIR spectroscopy combined with multivariate calibration analysis to quantify the carbon content of the soil Acre basin. We use 190 soil samples, collected in various locations of Acre basin, in order to test the NIR technique for determining the soil carbon content. We compared the NIR technique, dichromate oxidation in acidic media and elemental analysis methods. The amounts of carbon was obtained by oxidation and elemental analysis methods using the method of elemental analysis as a reference, it is found that the oxidation method recovered an average of 63.8% of carbon determined by the reference method. We suggest to adjust the amount of carbon obtained by the oxidation method should be adopted the coefficient 1.55. Regarding the use of NIR spectroscopy, the model developed for soil carbon analysis Acre basin by NIR spectroscopy showed good classification according to R 2 values and excellent rating under the RMSEC < RMSEP and RPD values, with reference to carbon determined by the elemental analysis method. Keywords : organic matter; Amazon; tropical soils; analytical methods.