湘东地区典型土壤团聚体稳定性的影响因素

目的]揭示湘东地区土壤团聚体的分布规律及其影响稳定性因素,为研究南方土壤团聚体胶结机制提供一定的理论依据。方法]在湘东地区选择3种常见成土母质(第四纪红土、花岗岩风化物、板岩风化物)上发育的典型自然林地、水田与旱地,采集表层土壤(0—20cm)与底层土壤(40—60cm),利用湿筛法测定土壤水稳性团聚体组成。结果]土地利用方式、母质类型及土层部位显著影响土壤团聚体的组成及稳定性,且它们的交互作用也非常明显。不同利用方式下土壤团聚体稳定性总体表现为:水田林地旱地;但利用方式对团聚体稳定性的影响仅局限于表层土壤,同时在花岗岩风化物发育质地较砂的土壤上表现不明显。不同母质间土壤团聚体稳定性呈现出如下规律:第四纪红土板岩风化物花岗岩风化物,但表层土壤或旱地、林地利用下该规律不甚明显。同时,表层土壤团聚体稳定性一般要显著高于底层土壤,但对于第四纪红土发育质地较为黏重的土壤或水田利用方式下并非如此。结论]成土母质、利用方式、土层部位通过对土壤质地、有机质、氧化物等的影响间接影响着湘东地区土壤团聚体的分布。

Factors Affecting Stability of Soil Aggregate in Eastern Hu'nan Province

Objective] To reveal the distribution pattern of soil aggregates and its influencing factors in the Eastern Hu''nan Province, in order to provide a theoretical basis for the study of soil aggregates cementation mechanism in Southern China.Methods] Typical natural forest land, dry land and paddy developed on three common soil-forming parent materials (quaternary red clay, weathered granite and shale) were selected in the Eastern Hu''nan Province. Totally, 54 soil samples from surface layer (0-20 cm) and bottom layer (40-60 cm) were collected. The water stable aggregate content of these soils were analyzed by wet sieving method.Results] Land use pattern, parent material type and soil location significantly affected the composition and stability of soil aggregates, and their interaction was also very obvious. Generally, the soil aggregate stability in paddy was the highest, while that in dry land was the lowest. But the influence of land use patterns on the stability of soil aggregates was limited to the surface soil, and it was not obvious in the soil developed from weathered granite. The soils developed from quaternary red clay had the highest aggregate stability, while the soils developed from weathered granite had the lowest aggregate stability, but this pattern was not exist for the soils in surface layer or soils in dry land and forest land. The soil aggregate stability of surface layer was usually higher than that of bottom layer, but there has no significant difference between surface or bottom layer in paddy or clay soils developed from quaternary red clay.Conclusion] The distribution of soil aggregates in the Eastern Hu''nan Province is influenced indirectly by soil parent material, utilization method and soil layer position through the influence of soil texture, organic matter and oxides.