Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy
González Pérez, Martha et al.--
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| Language: | English |
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Elsevier
2004-02
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| Subjects: | Tropical soil, No-till, Organic matter, Humification degree, |
| Online Access: | http://hdl.handle.net/10261/81863 http://dx.doi.org/10.13039/501100003593 |
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dig-irnas-es-10261-818632018-09-12T11:48:56Z Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy González Pérez, Martha Knicker, Heike Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil) Sao Paulo Research Foundation Tropical soil No-till Organic matter Humification degree González Pérez, Martha et al.-- The 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 13C nuclear magnetic resonance (13C NMR), Fourier transform infra-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 (1.74×1017 and 1.02×1017 spins g−1 HA, respectively), compared with 2.3×1017 spins g−1 HA for other soils under cultivation. The percentage of aromatic carbons determined by 13C NMR also decreases for noncultivated soil to 24%, being around 30% for samples of the other treatments. The solid-state 13C 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. The FAPESP (Projects: 97/05356-3, 98/15614-2 and 1998/ 14270-8) and PADCT/CNPq (project: 62 0324/98-8), Brazilian Agencies, are also acknowledged for financial support. Peer reviewed 2013-09-11T16:36:10Z 2013-09-11T16:36:10Z 2004-02 artículo http://purl.org/coar/resource_type/c_6501 Geoderma 118 (3-4): 181-190 (2004) 0016-7061 http://hdl.handle.net/10261/81863 1872-6259 http://dx.doi.org/10.13039/501100003593 en none Elsevier |
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Tropical soil No-till Organic matter Humification degree Tropical soil No-till Organic matter Humification degree |
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Tropical soil No-till Organic matter Humification degree Tropical soil No-till Organic matter Humification degree González Pérez, Martha Knicker, Heike Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| description |
González Pérez, Martha et al.-- |
| author2 |
Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil) |
| author_facet |
Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil) González Pérez, Martha Knicker, Heike |
| format |
artículo |
| topic_facet |
Tropical soil No-till Organic matter Humification degree |
| author |
González Pérez, Martha Knicker, Heike |
| author_sort |
González Pérez, Martha |
| title |
Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| title_short |
Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| title_full |
Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| title_fullStr |
Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| title_full_unstemmed |
Characterization of humic acids from a Brazilian Oxisol under different tillage systems by EPR, 13C NMR, FTIR and fluorescence spectroscopy |
| title_sort |
characterization of humic acids from a brazilian oxisol under different tillage systems by epr, 13c nmr, ftir and fluorescence spectroscopy |
| publisher |
Elsevier |
| publishDate |
2004-02 |
| url |
http://hdl.handle.net/10261/81863 http://dx.doi.org/10.13039/501100003593 |
| work_keys_str_mv |
AT gonzalezperezmartha characterizationofhumicacidsfromabrazilianoxisolunderdifferenttillagesystemsbyepr13cnmrftirandfluorescencespectroscopy AT knickerheike characterizationofhumicacidsfromabrazilianoxisolunderdifferenttillagesystemsbyepr13cnmrftirandfluorescencespectroscopy |
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