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为了解岩溶区土壤粒径分布与活性有机碳组分的关系,分别从岩溶区和碎屑岩区选取林地、灌草丛、果园三种主要土地利用类型,测定其土壤剖面的颗粒组成以及活性有机碳组分含量。结果表明,岩溶土壤与碎屑岩土壤粒径分布中,<0.002 mm粒组含量最大,均超过25%,且土壤质地以黏土为主。岩溶土壤总有机碳剖面分布呈凸肚型,其含量在剖面10~30 cm处达到最大值;而碎屑岩土壤总有机碳含量随着剖面深度的加深呈下降趋势,其含量在剖面0~10 cm处为最大值。除岩溶林地外,其余剖面的微生物量碳含量均随土壤深度的加深而减小,在剖面深度0~10 cm处为最大值,在70~90 cm处为最小值。岩溶区土壤溶解有机碳含量在不同深度的差值较小;碎屑岩区溶解有机碳含量在0~10 cm处为最大值,在20~30 cm处为最小值。岩溶区溶解有机碳含量与0.02~0.002 mm粒组呈显著负相关关系(p<0.05),与<0.002 mm粒组呈显著正相关关系(p<0.05);碎屑岩溶解有机碳含量与2~0.25 mm及0.25~0.05 mm粒组呈显著负相关关系(p<0.05),与<0.002 mm粒组呈显著正相关关系(p<0.05)。在不同土地利用方式中,林地土壤微生物量碳及溶解有机碳含量最大,灌草丛土壤次之,果园土壤最小,且果园土壤<0.002 mm粒组含量最小。
In order to understand the relationship between the distribution of soil particle size and active organic carbon in karst areas, the main land use types of forest, shrubs and orchards were selected from karst areas and clastic areas, respectively, and the particle composition and active organic Carbon content. The results show that in the distribution of karst soil and clastic rock, the grain size of <0.002 mm is the largest, both exceeding 25%, and the soil texture is dominated by clay. The distribution of total organic carbon in karst soil is convex and its content reaches the maximum at 10-30 cm section. The total organic carbon content in clastic soil decreases with the deepening of section depth, 10 cm at the maximum. Except karst forest, the contents of microbial biomass C and C in the other sections decreased with the deepening of soil depth, reaching the maximum at the depth of 0 ~ 10 cm and the minimum at 70 ~ 90 cm. The difference of soil dissolved organic carbon in the karst area was smaller at different depths. The dissolved organic carbon content in the clastic rock area was the maximum at 0-10 cm and the minimum at 20-30 cm. There was a significant negative correlation between dissolved organic carbon content in the karst area and the grain size of 0.02 ~ 0.002 mm (p <0.05) and a significant positive correlation with the grain size of <0.002 mm (p <0.05). The content of dissolved organic carbon ~ 0.25 mm and 0.25 ~ 0.05 mm granule group (p <0.05), and significant positive correlation with <0.002 mm granule group (p <0.05). Among different land use types, the content of soil microbial biomass carbon and dissolved organic carbon in forest land was the largest, followed by shrub and grassland soil, orchard soil and the orchard soil <0.002 mm grain group.