桂东南花岗岩崩岗区土壤团聚体稳定性及影响因素研究

Study on Soil Aggregate Stability and Influencing Factors in Granite Benggang Area of Southeast Guangxi

摘要:

团聚体是土壤结构的基本单元，其稳定性是评价土壤侵蚀的重要指标。为深入探究花岗岩崩岗区土壤团聚体稳定性及其影响因素，以桂东南花岗岩区典型崩岗为研究对象，采用干筛法和Elliott湿筛法测定崩岗侵蚀区土壤团聚体的粒径分布，并对含有粗颗粒的土壤样本进行去砂校正，进一步分析团聚体稳定性对崩岗侵蚀的影响。结果表明：（1）花岗岩崩岗区土壤机械稳定性团聚体以>2 mm为主，水稳性团聚体以<0.25 mm为主，土壤湿筛团聚体平均质量直径随土层加深呈现先减小后增大再减小的变化规律。对花岗岩土壤进行去砂校正减少湿筛误差，去砂分解值随土层深度增加而降低，表明深层土壤团聚体稳定性较差。（2）相关性分析结果表明，平均质量直径、粒径>0.25 mm团聚体含量、去砂分解值与土壤有机质、游离氧化铁含量及粉粒、黏粒含量均呈显著正相关性，与pH、砂粒含量呈显著负相关性。（3）冗余分析（RDA）研究发现，有机质含量和黏粒含量分别解释了土壤团聚体指标变化的89.82%和7.64%，共解释总变异的97.46%。提高土壤有机质和黏粒含量可以有效提高土壤团聚体的稳定性，从而降低崩岗侵蚀发生的风险。本研究阐明花岗岩红壤区团聚体稳定机制及其对崩岗侵蚀的影响，为区域生态安全和农业可持续发展提供科学依据。

Abstract:

【Objective】Soil aggregate is the basic unit of soil structure, and its stability is an important index to evaluate soil erosion. This study aimed to evaluate the stability and influencing factors of soil aggregates in the granite Benggang area, explore the relationship between aggregate stability and Benggang erosion, and provide a scientific basis for the prevention and control of Benggang erosion. 【Method】In this study, the typical Benggang in the granite area of southeastern Guangxi was taken as the research object. The dry sieving method and Elliott wet sieving method were used to determine the particle size distribution of soil aggregates in the Benggang erosion area, and the soil samples containing coarse particles were desanded to further analyze the effect of aggregate stability on Benggang erosion. 【Result】The results showed that: (1) The soil mechanically stable aggregates in the granite Benggang area were mainly >2 mm, and the water-stable aggregates were mainly <0.25 mm. The wet sieve average mass diameter of soil aggregates decreased first, then increased and then decreased with the deepening of soil layer. The sanding correction of granite soil reduced the wet sieve error, and the disaggregate reduction decreased with the increase of soil depth, indicating that the stability of deep soil aggregates was poor. (2) The results of correlation analysis showed that the average mass diameter, macro-aggregate content, and disaggregate reduction were significantly positively correlated with soil organic matter, free iron oxide content, silt and clay content, and significantly negatively correlated with pH and sand content. (3) Utilizing redundancy analysis, the study identified that organic matter content and clay content accounted for 89.82% and 7.64% of the variation in soil aggregate indicators, respectively, and explained 97.46% of the total variance. Increasing the levels of soil organic matter and clay content can significantly enhance the stability of soil aggregates, thus mitigating the risk of Benggang erosion. 【Conclusion】This study clarified the stabilization mechanisms of aggregates in the granite red soil region and their influence on Benggang erosion and provides a scientific basis for regional ecological security and sustainable agricultural development.