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为了研究喀斯特地区典型土壤有机碳积累与转化过程,采取野外取样分析与室内培养相结合的方法,以红壤为对照,采集2种喀斯特典型土壤(即棕色石灰土和黑色石灰土),设置不添加外源物质(CK)、添加14C标记的稻草(T1)、添加碳酸钙粉末(T2)和同时添加14C标记的稻草与碳酸钙粉末(T3)4个处理,进行室内培养试验,以土壤微生物指标(微生物生物量碳、基础呼吸、微生物碳熵和代谢熵)指示土壤有机碳积累与转化过程。结果表明,土壤有机碳矿化过程中,土壤呼吸的累积量依次为黑色石灰土>棕色石灰土>红壤(P<0.05)。微生物碳熵随土壤有机碳矿化变化依次为黑色石灰土>棕色石灰土>红壤(P<0.05)。同时添加外源稻草和钙对提高土壤微生物碳稳定性的效果最强。桂西北喀斯特地区土壤微生物指标的变化因土壤类型不同而存在差异。利用微生物指标来衡量土壤有机碳稳定性较为可靠。
In order to study the process of soil organic carbon accumulation and conversion in the typical Karst region, two Karst typical soils (ie, brown limestone and black limestone) were collected by field sampling and laboratory culture. CK, 14C-labeled straw (T1), calcium carbonate powder (T2) and 14C-labeled straw and calcium carbonate powder (T3) (Microbial biomass carbon, basic respiration, microbial carbon entropy and metabolic entropy) indicated the process of soil organic carbon accumulation and conversion. The results showed that the cumulative amount of soil respiration in soil organic carbon mineralization followed by black lime soil> brown lime soil> red soil (P <0.05). The soil microbial biomass entropy changed with black lime soil> brown lime soil> red soil (P <0.05). Simultaneous addition of exogenous straw and calcium has the strongest effect on improving soil microbial carbon stability. The variation of soil microbial index in the karst area of northwestern Guangxi is different due to different soil types. The use of microbial indicators to measure the stability of soil organic carbon is more reliable.