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| Structural Characteristics of Fulvic Acids from Aggregates of Black Soil Applied with Corn Stalks |
| Received:February 22, 2015 |
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| KeyWord:fulvic acid;aggregates;Fourier transformed infrared spectroscopy;element analysis;thermogravimetric analysis |
| Author Name | Affiliation | E-mail | | GUAN Song | College of Resource and Environmental Science, Jilin Agricultural University, Changchun 130118, China | | | DOU Sen | College of Resource and Environmental Science, Jilin Agricultural University, Changchun 130118, China | dousen1959@126.com |
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| Abstract: |
| An incubation experiment was conducted to study the effects of corn stalk additions on the structure characteristics of fulvic acid(FA) extracted from the whole soil and the macroaggregates(>2000 and 2000~250 μm), microaggregates(250~53 μm) and silt-clay fractions(<53 μm) in black soil by using element analysis, thermogravimetric(TG) analysis and Fourier transformed infrared(FTIR) spectroscopy. Results showed that the degrees of aromaticity, condensation and oxidation were higher in FA from macroaggregates than from microaggregates and silt-clay fractions in the control soil(no corn stalks added soil). Addition of corn stalks increased content of carbon, hydrogen and nitrogen, but decreased oxygen content in FA from the whole soil. Compared with the control soil, the molar ratios of carbon to hydrogen(C/H), oxygen to carbon(O/C), and carbon to nitrogen(C/N) of FA from corn stalks-treated soil reduced by 18.18%, 17.92%, and 19.17%, respectively, whereas the ratio of aliphatic carbon to aromatic carbon(aliphatic-C/aromatic-C) increased by 252.47%. The ratio of mass-lost at high temperature to medium temperature of FA was 51.85% lower in corn stalk treated soil than in the control soil. The aliphatic-C/aromatic-C ratios in FA from macroaggregates and microaggregates in corn stalk treated soil were 34.86%~604.35% more than those from the control soil. The aliphaticity of FA in whole soil increased, whereas the degrees of aromaticity, condensation and oxidation all decreased after corn stalk addition. For aggregate fractions, the degrees of aromaticity and oxidation were higher in FA from macroaggregates than those from microaggregates and silt-clay fractions after applying corn stalk to soil. Overall, FA from macroaggregates was more aromatic than that from microaggregates and silt-clay fractions. These results indicate that addition of corn stalks would make the FA structure become simpler in black soil. |
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