桂林毛村岩溶区三种亚类石灰土有机碳矿化研究

应用土壤培养法,比较分析了桂林毛村典型岩溶区黑色石灰土、棕色石灰土、红色石灰土三种亚类石灰土在25℃和70%田间饱和含水量条件下培养90d有机碳矿化速率的差异。结果显示:各亚类土壤有机碳矿化速率和累积释放CO2-C量总体上都随土层加深而递减。0～20cm至20～40cm层递减幅度最大。各亚类石灰土有机碳矿化速率和累计释放量的大小顺序为:黑色石灰土>棕色石灰土>红色石灰土,黑色石灰土的矿化速率远远大于棕色石灰土和红色石灰土,其中0～20cm土层差异最大。土壤有机碳矿化速率和有机碳含量呈正相关。黑色石灰土土壤有机碳矿化释放的CO2-C分配比例最高,达到3.33%,其次是红色石灰土,比例为2.92%,旱地棕色石灰土矿化比例最低,为1.90%,说明桂林毛村典型岩溶区黑色石灰土和红色石灰土有机碳稳定性较弱,旱地棕色石灰土具有较强的固定有机碳能力。

Organic Carbon Storage and Decomposition Rate of Three Subcategories of Calcareous Soil in Karst Area

Soil organic carbon(SOC) is an important component involved in the global carbon cycle and the influence of different sub-categories on SOC pools can significantly affect atomspheric CO2 concentrations.The response of soil carbon mineralization rates to different sub-categories is the crux for understanding the influence of different sub-categories on SOC.To determine the rate of SOC mineralization,each sub-category soil was collected and incubated in the laboratory at 25℃ with a constant moisture of 70% field water capacity over 90 days and the amount of cumulative CO2-C released over 90 days was compared among the different sub-categories of soil.It was found that there were no significant differences in the change of the fraction of cumulative CO2-C released by SOC mineralization with soil depth among the different sub-categories of soil.Decreasing rate between 0～20 cm and 20～40 cm soil layer was greatest.The decomposition rate and release cumulative amount of CO2 of three sub-categories are following the order: black calcareous soil>brown calcareous soil>red calcareous soil,the black calcareous soil mineralization rate is much greater than that of brown and red calcareous soils,in which the differences in 0～20 cm soil layer are largest.Mineralization rate of SOC and SOC contents displayed a positive correlattion.Black calcareous soil has the highest fraction of cumulative CO2-C released by SOC mineralization,and reached 3.33%.Secondly the fraction of the red calcareous soil is 2.92%.The Brown calcareous soil of cultivated land has the lowest fraction of cumulative CO2-C released by SOC mineralization by 1.90%,indicating that the stability of black calcareous soil and Red calcareous soil were weakly than Brown calcareous soil.The Brown calcareous soil of cultivated land has a strong capability to fix organic carbon.