HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Milori, D. M. B. P. Articles by Salton, J. Search for Related Content PubMed Articles by Milori, D. M. B. P. Articles by Salton, J. Agricola Articles by Milori, D. M. B. P. Articles by Salton, J. Related Collections Humic Substances Soil Analysis Soil Chemistry

Soil Chemistry

Organic Matter Study of Whole Soil Samples Using Laser-Induced Fluorescence Spectroscopy

^a Embrapa Agricultural Instrumentation, P.O. Box. 741, 13560-970, São Carlos-SP, Brazil
^b Federal Univ. of São Carlos, P.O. Box. 676, 13565-905, São Carlos-SP, Brazil
^c Univ. of São Paulo, Chemistry Institute of São Carlos, P.O. Box. 369, 13560-970, São Carlos-SP, Brazil
^d Soil Science Dep., Federal Univ. of Rio Grande do Sul, P.O. Box 15100, 90001-970, Porto Alegre-RS, Brazil
^e Embrapa West Agriculture, 79804-970, Dourados-MS, Brazil

^* Corresponding author (debora{at}cnpdia.embrapa.br)

Fluorescence spectroscopy relies on the fluorescence emitted by rigid conjugated systems and thus can be used to assess the soil organic matter (SOM) humification. This technique is generally applied to solution samples of humic substances, and so far no information exists about its applicability to whole untreated soil samples. The laser-induced fluorescence (LIF) spectroscopy is proposed as a novel technique to assess the organic matter humification in whole soil samples. We sampled the 0- to 2.5-, 2.5- to 5-, 5- to 10-, 10- to 15-, and 15- to 20-cm layers of three Oxisols of long-term experiments located in two sites of the Brazilian Cerrado. The humification index based on LIF spectroscopy (H_LIF) of whole soil samples showed a close correlation with the humification indexes A₄/A₁, I₄₆₅/I₃₉₉, and A₄₆₅ obtained after fluorescence spectroscopy analysis of the dissolved humic acids. The H_LIF in soils under native cerrado or subjected to no-tillage increased from the top to the deepest layer, which is consistent with the deposition of labile organic matter from plant residues on the soil surface. The soils subjected to conventional tillage, however, showed relatively constant H_LIF along the profile, possibly because homogenization imparted by disturbance of the arable layer. Accordingly, for the two top layers, the soils under no-tillage showed a lower H_LIF than for conventionally tilled soils. Laser-induced fluorescence spectroscopy is a promising technique to assess humification in whole soil samples, particularly in Oxisols, which due to high concentration of Fe³⁺ are not feasible to electron spin resonance (ESR) and Carbon-13 nuclear magnetic resonance (¹³C NMR) spectroscopy, unless previous treatment is employed.

Abbreviations: ESR, Electron Spin Resonance • H_LIF, Humification index based on Laser-Induced Fluorescence spectroscopy • LIF, Laser-Induced Fluorescence • NMR, Nuclear Magnetic Resonance • SOM, soil organic matter