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Characterization of anthropogenic dark Earths by diffuse reflectance spectroscopy and X-ray fluorescence

Grant number: 15/26026-1
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): May 01, 2016
Effective date (End): December 31, 2016
Field of knowledge:Agronomical Sciences - Agronomy - Soil Science
Principal researcher:José Marques Júnior
Grantee:Ana Beatriz Coelho França
Home Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Diffuse reflectance spectroscopy (DRS) and Spectrometry fluorescence x-rays (EFRX) are promising techniques in the indirect determination of soil attributes. However, few studies use these techniques to characterize the Amazon Dark Earth (TPA). In this sense, this study will characterize the TPA located at Southern of Amazonas using non-destructive techniques called DRS and EFRX in order to estimate the presence of iron oxides and to determine the presence of elements of agronomic importance (K, Mg, Ca and P); and to compare the results with traditional methods of iron oxide characterization (x-ray diffraction) and sulfuric attack. It was collect seven TPA profiles and one forest profile located between the two cities Apuí and Manipur-AM, totaling 39 samples. The reflectance values will be determined using 0.5 grams of dry ground samples (TFSA) in a Perkin Elmer Lambda 950 spectrophotometer with integrating sphere equipped, every 0.5 nm, making a scan in the range of 380 to 2,500 nm. For EFRX analysis will be used approximately 3 grams of soil, put under a Mylar® film 6 microns thick. Using the DRS analysis, the hematite (Hm) and goethite (Gt) contents will be estimated as well as the reason Hm/Hm + Gt. In addition, using the EFRX analysis will be quantified the potassium (K), phosphorus (P),magnesium (Mg), calcium (Ca), aluminum (Al), iron (Fe) and silicon (Si)contents. The results will be organized in tables for comparison between the horizons and studied trenches. The results obtained by the DRS and EFRX will be correlated with the values obtained in previous reports which we used the X-ray diffraction and sulfuric attack.