添加^14C标记稻草对喀斯特典型土壤有机碳矿化的影响

为了研究有机物质对喀斯特地区典型土壤有机碳积累与转化的影响,采集两种喀斯特典型土壤（棕色石灰土、黑色石灰土）和一种对照土壤（红壤）的表层土壤（0～15cm）,设置不添加外源物质（CK）和添加14C标记的稻草（T1）的处理,进行为期100d的土壤培养试验及矿化试验。测定并分析了这3种典型土壤类型的微生物生物量碳（MBC）表观周转时间和田间周转时间、外源有机物质对土壤原有有机碳的激发效应以及CO2释放量。结果表明：MBC表观周转时间和田间周转时间依次分别为（71±2）d、（243±20）d、（254±45）d和0.29、1.0、1.04a。添加标记的14C有机物质后,土壤原有有机质的激发效应大小依次为红壤〉棕色石灰土〉黑色石灰土。在相同条件下,红壤不利于土壤有机质的累积,而棕色石灰土和黑色石灰土有利于土壤有机质的累积。

Effect to the Turnover of Soil Organic Carbon in Three Typical Soils in Karst Area by Adding ^14C-labelled Organic Matter

In order to indicate the effect of organic matter on soil organic carbon（SOC） turnover, two Karst soils（terra fusca and rendzina） and a contrast soil（red soil） were chosen（0～15 cm） for a study. Three typical soil samples were selected and a 100 d incubation experiment was conduct with no added（CK） and 14C-straw added（T1） treatment. Mineralization of SOC, microbial biomass C and field turnover time of microbial biomass were measured and analyzed in 100d- soil incubation experiments. The result showed that gross and field turnover time of microbial biomass were（71 ± 2）d,（243 ± 20）d,（254 ± 45）d and 0.29 a, 1.00 a, 1.04 a. Adding exogenous organic matter had positive excitation in red soil, negative excitation in terra fusca, no excitation in rendzina. This showed that in the same condition, rendzina and terra fusca are more likely to accumulation of organic carbon than red soil.