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为阐明喀斯特地区土壤演变过程(脱钙镁富铁铝化作用)中土壤特有矿物对碳释放的影响,本文以喀斯特区典型的高和低有机碳含量水平的棕色石灰土和红壤为研究对象,通过80 d室内培养试验,研究土壤碳释放(有机碳和无机碳)对添加土壤中特有矿物质(Ca14CO3和Fe(OH)3)的响应。结果表明:添加Ca14CO3和Fe(OH)3均对棕色石灰土和红壤中原有碳的释放有正激发效应,以前者(培养结束时土壤原有碳累积释放量为823.8~1367.2 mg·kg-1)显著大于后者(502.5~635.7 mg·kg-1),说明喀斯特地区土壤由富钙镁的石灰土向富铁铝的红壤演变过程可能是土壤碳库逐渐稳定的过程。添加Ca14CO3和Fe(OH)3后,土壤原有碳的累积释放量的大小与土壤有机碳本身含量水平密切相关,均以高量有机碳红壤>低量有机碳红壤和石灰土>高量有机碳石灰土(P<0.05)。培养过程中,无论是添加Ca14CO3还是Fe(OH)3,土壤可溶性有机碳(DOC)含量与碳释放激发效应的变化趋势一致,表明DOC可用于指示棕色石灰土和红壤激发效应强弱。土壤微生物生物量碳与碳释放激发效应的变化趋势不一致,说明添加Ca14CO3或Fe(OH)3对土壤原有碳的激发效应主要源于外源物添加后改变了土壤物理和化学环境,而土壤微生物的贡献相对较少。
In order to elucidate the effect of soil-specific minerals on carbon release in the process of soil evolution (decalcification of magnesium and iron-aluminum in decalcified magnesia), the brown lime-soil and red soil, which are characterized by high and low levels of organic carbon in karst regions, Through 80 d incubation experiments, the responses of soil carbon (organic and inorganic carbon) to soil-specific minerals (Ca14CO3 and Fe (OH) 3) were studied. The results showed that both Ca14CO3 and Fe (OH) 3 had a positive excitation effect on the release of carbon from brown limestone soil and red soil. The former (the cumulative carbon emission from the soil at the end of cultivation was 823.8 ~ 1367.2 mg · kg-1 ) Was significantly higher than that of the latter (502.5-635.7 mg · kg-1), indicating that the evolution of red soil from calcium-rich calcareous soil to iron-rich aluminum in karst area may be the process of gradual stabilization of soil carbon pool. After the addition of Ca14CO3 and Fe (OH) 3, the cumulative amount of released carbon in soil was closely related to the content of soil organic carbon. Both organic carbon red soil> low amount organic carbon red soil and lime soil> high amount organic Carbonated lime soil (P <0.05). During the cultivation process, both the content of DOC and the release of carbon were the same whether it was added Ca14CO3 or Fe (OH) 3, indicating that DOC can be used to indicate the intensity of excitation effect of brown limestone and red soil. The variation trend of soil microbial biomass carbon and carbon emission excitation was inconsistent, indicating that the stimulating effect of adding Ca14CO3 or Fe (OH) 3 on the original carbon in soil was mainly due to the change of soil physical and chemical environment after the addition of exogenous substances, The contribution of microorganisms is relatively small.