不同树龄橡胶林黏土矿物组成及钾素形态特征

Clay Mineral Composition and Potassium Forms in Rubber Plantations of Different Ages

  • 摘要:
    目的 研究热带地区橡胶林土壤中黏土矿物组成和不同形态钾含量随树龄增长的演变规律以及影响因素,为我国热区橡胶林的钾素科学管理和持续健康生产提供科学依据。
    方法 在海南岛西部橡胶主产区选择4片不同树龄(10 a、20 a、30 a和40 a)的橡胶人工林,采集0 ~ 20 cm、20 ~ 40 cm、40 ~ 60 cm、60 ~ 80 cm和80 ~ 100 cm土壤剖面样品,分析土壤理化性质、不同形态钾含量,利用X射线衍射(XRD)分析黏土矿物组成。
    结果 水溶性钾(WSK)和交换性钾(EK)均受树龄和土层深度以及二者交互作用的影响,其中0 ~ 20 cm土层的WSK随树龄的增长呈增加的趋势,EK随土层深度的增加呈降低趋势;缓效钾(SAK)和全钾(TK)仅受树龄因素的显著影响,其中,10 a树龄的橡胶林土壤中TK显著低于20 ~ 40 a树龄。随树龄的增长,高岭石相对含量减少,而水云母相对含量增加,二者存在此消彼长的关系。相关性分析表明,EK与土壤有机碳(SOC)含量、全氮(TN)含量以及碳氮比(C/N)呈极显著正相关,而TK与pH和C/N间呈极显著正相关;WSK、SAK以及TK含量与高岭石含量呈显著负相关,而与水云母含量呈显著正相关。
    结论 综上所述,橡胶树龄显著影响土壤不同形态钾素含量及黏土矿物组成,随树龄增长,高岭石向水云母转化,进而提高了土壤不同形态钾素含量;土壤有机碳含量的增加对交换性钾具有正向调控作用。因此,在橡胶生产中可通过有机质培肥来促进土壤钾素有效性提升。研究结果对橡胶林钾素的科学管理具有指导意义。

     

    Abstract:
    Objective This study aimed to investigate the evolution patterns of different forms of potassium (K) and clay mineral composition with plantation age and associated influencing factors in tropical rubber plantation soils, in order to provide a scientific basis for K management and sustainable production in rubber plantations in tropical regions of China.
    Method Four rubber plantations with different ages (10 a, 20 a, 30 a and 40 a) were selected from the main rubber producing areas in the west of Hainan Island, and soil samples were collected at depths of 0 ~ 20 cm, 20 ~ 40 cm, 40 ~ 60 cm, 60 ~ 80 cm and 80 ~ 100 cm. Soil physicochemical properties and the contents of different forms of K were analyzed. Clay mineral composition was determined using X-ray diffraction (XRD).
    Result Water-soluble K (WSK) and exchangeable K (EK) were both influenced by planting age, soil depth and their interaction. WSK showed an increasing trend with planting age in the 0 ~ 20 cm layer, while EK exhibited a decreasing trend with increasing soil depth. Slow available K (SAK) and total K (TK) were significantly influenced only by planting age, with TK being significantly lower at 10 years compared to 20 ~ 40 years. As planting age increased, the relative content of kaolinite decreased, while that of hydromica increased, indicating a trade-off relationship between the two minerals. Correlation analysis revealed a highly significant positive correlation between EK and soil organic carbon (SOC), total nitrogen (TN), and carbon-to-nitrogen ratio (C/N), while TK showed a highly significant positive correlation with pH and C/N. WSK, SAK and TK contents exhibited a significant negative correlation with kaolinite content and a significant positive correlation with hydromica content.
    Conclusion Planting age significantly influenced the different forms of K and clay mineral composition in soil. There was a shift form of kaolinite to hydromica with increasing age, leading to higher levels of different forms of K in soil. Increased SOC positively regulated EK. Therefore, organic matter fertilization should be utilized to enhance K effectiveness. The research findings can guide the scientific management of K in rubber production.

     

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