Moisture effect on soil humus characteristics in a laboratory incubation experiment
A 180-day laboratory incubation experiment (30°C) was conducted to investigate the quantitative and qualitative characteristics of humic fractions in a Mollisol at different moisture conditions. The soil moisture contents were 30, 60, and 250% field water-holding capacity (WHC), which represented th...
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| Format: | Article |
| Language: | English |
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Czech Academy of Agricultural Sciences
2016-03-01
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| Series: | Soil and Water Research |
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| Online Access: | https://swr.agriculturejournals.cz/artkey/swr-201601-0005_moisture-effect-on-soil-humus-characteristics-in-a-laboratory-incubation-experiment.php |
| _version_ | 1797897874535612416 |
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| author | Cuilan LI Shuqing GAO Jinjing ZHANG Lanpo ZHAO Lichun WANG |
| author_facet | Cuilan LI Shuqing GAO Jinjing ZHANG Lanpo ZHAO Lichun WANG |
| author_sort | Cuilan LI |
| collection | DOAJ |
| description | A 180-day laboratory incubation experiment (30°C) was conducted to investigate the quantitative and qualitative characteristics of humic fractions in a Mollisol at different moisture conditions. The soil moisture contents were 30, 60, and 250% field water-holding capacity (WHC), which represented the low, middle, and high moisture levels, respectively. The results showed that the carbon contents of the total soil and corresponding humic fractions generally decreased with increasing soil moisture. A significant difference was observed between the 250% WHC and the two other moisture levels. By contrast, the carbon content of the water soluble fraction significantly increased with increasing soil moisture levels. The solid-state 13C nuclear magnetic resonance (NMR) spectra showed that the alkyl C/O-alkyl C, aliphatic C/aromatic C, and hydrophobic C/hydrophilic C ratios were in the order of 250% WHC > 30% WHC ≍ 60% WHC, 30% WHC ≍ 60% WHC > 250% WHC and 250% WHC > 60% WHC ≍ 30% WHC for humic acid, and 250% WHC > 30% WHC ≍ 60% WHC, 60% WHC ≍ 250 % WHC > 30% WHC and 30% WHC ≍ 250% WHC > 60% WHC for humin, respectively. These results indicated that a high moisture level was unfavourable for the carbon accumulation of the total soil and humic fractions, whereas it was favourable for the accumulation of water soluble carbon. Although soil moisture levels had a distinct effect on the chemical composition of humic acid and humin, the decomposition degree of the two humic substances components, as indicated by the alkyl C/O-alkyl C ratio, were both higher at a high moisture level than at a low moisture level. Therefore, the lower soil organic carbon content at a high moisture level than at a low moisture level can be ascribed to the higher water soluble carbon content and larger decomposition degree of humic acid and humin in the former. Our results are important for understanding the behaviour and mechanisms of humic substances at specific soil moisture conditions. |
| first_indexed | 2024-04-10T08:04:10Z |
| format | Article |
| id | doaj.art-7b80da6b13d7491682fec669e2aefbdf |
| institution | Directory Open Access Journal |
| issn | 1801-5395 1805-9384 |
| language | English |
| last_indexed | 2024-04-10T08:04:10Z |
| publishDate | 2016-03-01 |
| publisher | Czech Academy of Agricultural Sciences |
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| series | Soil and Water Research |
| spelling | doaj.art-7b80da6b13d7491682fec669e2aefbdf2023-02-23T03:48:32ZengCzech Academy of Agricultural SciencesSoil and Water Research1801-53951805-93842016-03-01111374310.17221/21/2015-SWRswr-201601-0005Moisture effect on soil humus characteristics in a laboratory incubation experimentCuilan LI0Shuqing GAO1Jinjing ZHANG2Lanpo ZHAO3Lichun WANG4National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, P.R. China;College of Resource and Environmental Science, Jilin Agricultural University, Changchun, P.R. ChinaCollege of Resource and Environmental Science, Jilin Agricultural University, Changchun, P.R. ChinaCollege of Resource and Environmental Science, Jilin Agricultural University, Changchun, P.R. ChinaInstitute of Agricultural Resources and Environments, Jilin Academy of Agricultural Sciences, Changchun, P.R. ChinaA 180-day laboratory incubation experiment (30°C) was conducted to investigate the quantitative and qualitative characteristics of humic fractions in a Mollisol at different moisture conditions. The soil moisture contents were 30, 60, and 250% field water-holding capacity (WHC), which represented the low, middle, and high moisture levels, respectively. The results showed that the carbon contents of the total soil and corresponding humic fractions generally decreased with increasing soil moisture. A significant difference was observed between the 250% WHC and the two other moisture levels. By contrast, the carbon content of the water soluble fraction significantly increased with increasing soil moisture levels. The solid-state 13C nuclear magnetic resonance (NMR) spectra showed that the alkyl C/O-alkyl C, aliphatic C/aromatic C, and hydrophobic C/hydrophilic C ratios were in the order of 250% WHC > 30% WHC ≍ 60% WHC, 30% WHC ≍ 60% WHC > 250% WHC and 250% WHC > 60% WHC ≍ 30% WHC for humic acid, and 250% WHC > 30% WHC ≍ 60% WHC, 60% WHC ≍ 250 % WHC > 30% WHC and 30% WHC ≍ 250% WHC > 60% WHC for humin, respectively. These results indicated that a high moisture level was unfavourable for the carbon accumulation of the total soil and humic fractions, whereas it was favourable for the accumulation of water soluble carbon. Although soil moisture levels had a distinct effect on the chemical composition of humic acid and humin, the decomposition degree of the two humic substances components, as indicated by the alkyl C/O-alkyl C ratio, were both higher at a high moisture level than at a low moisture level. Therefore, the lower soil organic carbon content at a high moisture level than at a low moisture level can be ascribed to the higher water soluble carbon content and larger decomposition degree of humic acid and humin in the former. Our results are important for understanding the behaviour and mechanisms of humic substances at specific soil moisture conditions.https://swr.agriculturejournals.cz/artkey/swr-201601-0005_moisture-effect-on-soil-humus-characteristics-in-a-laboratory-incubation-experiment.phphumic acidhuminhumus compositionsoil moisturesolid-state 13c nmr |
| spellingShingle | Cuilan LI Shuqing GAO Jinjing ZHANG Lanpo ZHAO Lichun WANG Moisture effect on soil humus characteristics in a laboratory incubation experiment Soil and Water Research humic acid humin humus composition soil moisture solid-state 13c nmr |
| title | Moisture effect on soil humus characteristics in a laboratory incubation experiment |
| title_full | Moisture effect on soil humus characteristics in a laboratory incubation experiment |
| title_fullStr | Moisture effect on soil humus characteristics in a laboratory incubation experiment |
| title_full_unstemmed | Moisture effect on soil humus characteristics in a laboratory incubation experiment |
| title_short | Moisture effect on soil humus characteristics in a laboratory incubation experiment |
| title_sort | moisture effect on soil humus characteristics in a laboratory incubation experiment |
| topic | humic acid humin humus composition soil moisture solid-state 13c nmr |
| url | https://swr.agriculturejournals.cz/artkey/swr-201601-0005_moisture-effect-on-soil-humus-characteristics-in-a-laboratory-incubation-experiment.php |
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