岩溶区土地利用方式对土壤有机碳组分及其分布特征的影响

Effects of Land Use on Soil Organic Carbon Fractions and Its Distribution in Karst

对重庆市中梁山低山岩溶区角砾状白云质灰岩的黄色石灰土剖面进行研究。结果表明:土地利用方式明显地影响了土壤微生物量碳、微生物商、可矿化碳和硫酸钾浸提碳的含量,微生物商能更准确的反映土壤有机碳库对土地利用方式的响应,微生物商依次为:菜地>橘林地>耕地>草地>灌丛,平均值分别为3.09,2.46,1.92,1.55和1.14。土壤微生物量碳和微生物商在土壤0-30 cm范围内的变化规律不明显,仅在灌丛中的变化相似;而可矿化碳和硫酸钾浸提碳基本上随土壤深度的增加而降低,规律性明显。相关分析说明,硫酸钾浸提碳与全氮、水解氮和速效钾相关极显著,与全磷相关显著,相关系数分别为0.421,0.375,0.576和0.274,可以作为土壤肥力变化的重要指标;机械组成分析中砂粒对土壤有机碳组分的分布和含量影响相对比较明显,与土壤微生物量碳相关极显著(0.355),与土壤可矿化碳相关显著(0.313)。

As an essential indicator of soil quality, soil organic carbon and its tractions play key role m soil chemical, physical, and biological properties. To assess the effects of land use on soil organic carbon fractions, soil samples were taken from Zhongliang knoll,Chongqing. Results revealed that the types of land use had a significant influence to the content of soil microbial biomass carbon, Cmie-to-Corg, mineralizable carbon and soil K2SO4- soluble carbon, Cmic-to-Corg are more realistic reflection of soil organic carbon pool on the land use patterns of response, Cmic-to-Corg in different land use were vegetable land （3.09）〉 orange land （2.46）〉 slopping field （1.92） 〉grassland （1.55）〉shrub land （1.14）. The changes of soil microbial biomass carbon and Cmic-to-Corg in the soil from the surface to 30cm were not obvious, but the changes of them were similar in the shrub land. mineralizable carbon and soil K2SO4--soluble carbon concentration decreased slowly with the increase in soil depth. Correlation analysis showed that soil K K2SO4-soluble earhon and total P was significantly, more significant correlations between soil K2SO4-soluble carbon and total N, hydrolysable N, available K were found with the coefficients of 0. 421,0. 375,0. 576, so the soil K2SO4- soluble carbon can be used as an important indicator of changes in soil fertility. The sand in soil constituents has obviously effected the content of soil organic carbon fractions and its distributions, correlation analysis showed more significant correlations between soil microbial biomass carbon and sand was found with 0. 355, significant between mineralizable carbon and sand was found with 0. 313.