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研究岩溶区与非岩溶区土壤有机碳及其与养分之间的关系异同,有利于揭示岩溶区土壤有机碳的积累机制。以广西桂林毛村岩溶试验场为采样点,采集岩溶区、混合区和非岩溶区典型水稻田、柑橘园和玉米地的表层土壤,采用常规方法测定土壤有机碳、养分和特征元素含量并分析它们之间的相关性。结果显示,3种土地利用方式下,岩溶区土壤有机碳、全氮、pH和交换性Ca~(2+)均显著高于非岩溶区。岩溶区水稻田中土壤溶解性有机碳和碱解氮含量显著低于非岩溶区,而土壤阳离子交换量和交换性Mg~(2+)却显著较高。但是,这4个指标在柑橘园和玉米地中无显著差异。统计结果显示,3种土地利用方式下,土壤全氮含量与土壤有机碳含量呈极其显著正相关(p<0.01);就水稻田土壤而言,土壤有机碳与阳离子交换量和交换性Ca~(2+)分别呈极其显著正相关(p<0.01)和显著正相关(p<0.05)。以上研究结果表明:较高pH、全氮和交换性Ca~(2+)含量是维持岩溶区较高土壤有机碳含量的重要因素,而3种土地利用方式中水稻田土壤有机碳积累量最高。
Studying the relationship between soil organic carbon in karst and non-karst areas and its relationship with nutrients is helpful to reveal the mechanism of soil organic carbon accumulation in karst areas. Soil samples of karst, mixed and non-karst paddy fields, citrus orchards and corn fields were collected from Guilin Mao-Mao Karst Experimental Site. The contents of soil organic carbon, nutrients and characteristic elements were determined by routine methods Relevance between them. The results showed that soil organic carbon, total nitrogen, pH and exchangeable Ca ~ (2+) in karst areas were significantly higher than those in non-karst areas under the three land use patterns. The contents of soil dissolved organic carbon and available nitrogen in paddy field of karst area were significantly lower than those in non-karst area, but the soil cation exchange capacity and exchangeable Mg 2+ content were significantly higher. However, these four indicators showed no significant differences between citrus orchards and corn fields. The statistical results showed that under the three land use patterns, the total nitrogen content in soil was positively correlated with the soil organic carbon content (p <0.01). For the paddy soil, the soil organic carbon and cation exchange capacity and the exchangeable Ca ~ (P <0.01) and significant positive correlation (P <0.05). The above results show that high pH, total nitrogen and exchangeable Ca ~ (2+) content are important factors in maintaining high soil organic carbon content in karst areas, while the three kinds of land use types have the highest soil organic carbon accumulation in paddy soils .