鄂南第四纪粘土红壤团聚体的稳定性及其稳定机制初探

用湿筛法和LeBissonnais法研究了鄂南第四纪红粘土母质发育的两种侵蚀程度的红壤团聚体的稳定性,并且分析了影响供试土壤团聚体稳定性的土壤性质。结果表明,轻度侵蚀的耕作土壤团聚体的稳定性较低,在水的作用下易崩解成较小粒径的水稳性团聚体;强度侵蚀的土壤表层团聚体的稳定性较高,崩解后产生较多的水稳性大团聚体。引起土壤团聚体破坏的主要作用机制是土壤团聚体中的闭蓄空气爆破引起的消散作用;研究区第四纪红壤团聚体的主要胶结物质是土壤中的粘粒、游离氧化铁铝和无定形铁。由于供试土壤中有机质含量很低,在本研究中,有机质含量与土壤团聚体稳定性之间没有显著正相关关系。

Aggregate Stability and Stable Mechanism of Aggregate Derived from Quaternary Red Clay in South of Hubei Province

The aggregates of slightly eroded red soil and severely eroded red soil derived from Quaternary red clay were used to understand the stability and the breakdown mechanisms by applying wetting sieving method and Le Bissonnais method, and the relationship between aggregate stability and some soil properties, such as different forms of Fe oxides and Al oxides,organic matters,CEC and clay content were also studied. The results of the study indicated that: the aggregates of severely eroded soils were more stable than those of the slightly eroded soils; The slaking of entrapped air in aggregate destroyed the aggregate severely, especially for the slightly eroded soils. Meanwhile mechanical breakdown and micro-cracking did little on the aggregates. The aggregate stability positively related with the percentage of Fe_d, Al_d, Fe_o and clay content, but negatively related to the SOC, which may because the low organic matters in the severely eroded soils and the effect of cultivation.