Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, C-13 NMR, FTIR and fluorescence spectroscopy

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dc.contributor.authorGonzalez Perez, M.
dc.contributor.authorMartin-Neto, L.
dc.contributor.authorSaab, S. C.
dc.contributor.authorNovotny, E. H.
dc.contributor.authorMilori, DMBP
dc.contributor.authorBagnato, V. S.
dc.contributor.authorColnago, L. A.
dc.contributor.authorMelo, W. J.
dc.contributor.authorKnicker, H.
dc.contributor.institutionEmpresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniv Estadual Ponta Grossa
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionTech Univ Munich
dc.date.accessioned2014-05-20T15:22:00Z
dc.date.available2014-05-20T15:22:00Z
dc.date.issued2004-02-01
dc.description.abstractThe importance of soil organic matter functions is well known, but structural information, chemical composition and changes induced by anthropogenic factors such as tillage practices are still being researched. In the present paper were characterized Brazilian humic acids (HAs) from an Oxisol under different treatments: conventional tillage/maize-bare fallow (CT1); conventional tillage/maize rotation with soybean-bare fallow (CT2)-, no-till/maize-bare fallow (NT1); no-till/maize rotation with soybean-bare fallow (NT2); no-till/maize-cajanus (NT3) and no cultivated soil under natural vegetation (NC). Soil HA samples were analyzed by electron paramagnetic resonance (EPR), solid-state C-13 nuclear magnetic resonance (C-13 NMR), Fourier transform intra-red (FTIR) and UV-Vis fluorescence spectroscopies and elemental analysis (CHNS). The FTIR spectra of the HAs were similar for all treatments. The level of semiquinone-type free radical determined from the EPR spectra was lower for treatments no-till/maize-cajanus (NT3) and noncultivated soil (1.74 X 10(17) and 1.02 x 10(17) spins g(-1) HA, respectively), compared with 2.3 X 10(17) spins g(-1) HA for other soils under cultivation. The percentage of aromatic carbons determined by C-13 NMR also decreases for noncultivated soil to 24%, being around 30% for samples of the other treatments. The solid-state C-13 NMR and EPR spectroscopies showed small differences in chemical composition of the HA from soils where incorporation of vegetal residues was higher, showing that organic matter (OM) formed in this cases is less aromatic. The fluorescence intensities were in agreement with the percentage of aromatic carbons, determined by NMR (r = 0.97 P < 0.01) and with semiquinone content, determined by EPR (r = 0.97 P < 0.01). No important effect due to tillage system was observed in these areas after 5 years of cultivation. Probably, the studied Oxisol has a high clay content that offers protection to the clay-Fe-OM complex against strong structural alterations. (C) 2003 Elsevier B.V. All rights reserved.en
dc.description.affiliationEmbrapa Instrument Agropecuaria, BR-13560970 Sao Carlos, SP, Brazil
dc.description.affiliationUniv São Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil
dc.description.affiliationUniv Estadual Ponta Grossa, Dept Fis, Ponta Grossa, PR, Brazil
dc.description.affiliationUniv São Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP, Brazil
dc.description.affiliationUniv Estadual Paulista, Fac Ciências Agrarias & Vet, BR-14870000 Jaboticabal, SP, Brazil
dc.description.affiliationTech Univ Munich, Dept Soil Sci, D-85350 Freising Weihenstephan, Germany
dc.description.affiliationUnespUniv Estadual Paulista, Fac Ciências Agrarias & Vet, BR-14870000 Jaboticabal, SP, Brazil
dc.format.extent181-190
dc.identifierhttp://dx.doi.org/10.1016/S0016-7061(03)00192-7
dc.identifier.citationGeoderma. Amsterdam: Elsevier B.V., v. 118, n. 3-4, p. 181-190, 2004.
dc.identifier.doi10.1016/S0016-7061(03)00192-7
dc.identifier.issn0016-7061
dc.identifier.urihttp://hdl.handle.net/11449/33063
dc.identifier.wosWOS:000188296800003
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofGeoderma
dc.relation.ispartofjcr3.740
dc.relation.ispartofsjr1,717
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjecttropical soilpt
dc.subjectno-tillpt
dc.subjectorganic matterpt
dc.subjecthumification degreept
dc.titleCharacterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, C-13 NMR, FTIR and fluorescence spectroscopyen
dc.typeArtigo
dcterms.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dcterms.rightsHolderElsevier B.V.
unesp.author.orcid0000-0003-1253-7174[5]
unesp.author.orcid0000-0002-9516-9022[7]
unesp.author.orcid0000-0001-9781-0082[1]
unesp.author.orcid0000-0003-2683-0347[8]
unesp.author.orcid0000-0002-0483-2109[9]

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