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| Organic carbon mineralization characteristics of red soil aggregate fractions in sloping farmland with different planting patterns |
| Received:December 15, 2020 |
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| KeyWord:sloping farmland;red soil;planting patterns;soil aggregates;organic carbon mineralization;kinetic equation |
| Author Name | Affiliation | E-mail | | WU Damu | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | FAN Maopan | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | ZHAO Jixia | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Xiaomei | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Yongmei | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | youngmaylee@126.com |
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| Abstract: |
| To explore the mechanism of organic carbon transformation and stabilization with aggregate fractions under different planting patterns, the red soil of sloping farmland was selected as the research object, combined with soil aggregate composition and organic carbon distribution. Using the indoor organic carbon mineralization cultivation method, the first-order kinetic equation was used to fit the dynamic changes in the CO2 flux during the cultivation process, and the dynamic characteristics of aggregate organic carbon mineralization and its contribution to the total soil mineralization under different planting patterns were analyzed. The results showed that the particle size of soil aggregates were mainly >2 mm and 2~0.25 mm, the total amount of aggregates reached more than 78%. Corn（Zea mays）monoculture significantly reduced the proportion of >2 mm aggregates but significantly increased the proportion of <0.25 mm aggregates. The organic carbon content of <0.25 mm aggregates was significantly higher than that of bulk soils, >2 mm aggregates, and 2~0.25 mm aggregates under different planting patterns. The soil organic carbon（SOC）content of the corn-soybean（Glycine max）intercropping treatment in the bulk soils was significantly lower than that of the soybean single-cropping treatment. There was no significant difference between the organic carbon content of the aggregate fractions between monoculture treatment and the corresponding intercropping treatment. The mineralization of organic carbon in bulk soils and aggregates under different planting patterns revealed that it was stronger in monocultures than in intercropping, while the cumulative mineralization of organic carbon was the highest in soybean monoculture. The organic carbon turnover rate of 2~0.25 mm aggregates was the fastest and the organic carbon mineralization was the strongest, whereas the C0 / SOC value（the proportion of SOC consumption by SOC mineralization and decomposition）of <0.25 mm aggregates was significantly lower than that of the bulk soils and the other two particle size aggregates, which was more conducive to SOC sequestration. The >2 mm and 2~0.25 mm aggregates contributed the most to total SOC mineralization. These results indicated that macroaggregates（>0.25 mm）play an important role in organic carbon mineralization in red soil of sloping farmland. Corn-soybean intercropping and corn-radish intercropping could reduce SOC mineralization and enhance soil carbon sequestration capacity to certain extent. |
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