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应用湿筛法、Emerson法、机械和化学分散法、LeBissonnaia法对亚热带第四纪红土发育的富铁土团聚体组成和稳定性进行评价,土壤团聚体数量和稳定性指标分别用>0.25mm水稳性团聚体含量(WSA)、团聚体平均重量直径(MWD)和团聚体破坏率(PAD)表示。结果表明,3种方法测定的MWD值呈极显著正相关;土壤团聚体数量和稳定性与土地利用方式密切相关,林地和园地较高,荒地和母质最低;5～2、2～1和1～0.5mm团聚体经快速湿润(FW)、慢速湿润(SW)和预湿后扰动(WS)处理后,团聚体MWD均表现为WS>SW>FW,相对消散系数(RSI)为31%～45%,表明团聚体崩解的主要物理机制是团聚体中闭塞空气引起的消散作用。3种方法具有可比性,反映土壤团聚体特性和稳定机制,可将其团聚体数量和稳定性指标作为衡量土壤质量和抗蚀性的重要指标。
The composition and stability of soil-rich iron-rich aggregates in sub-tropical Quaternary laterites were evaluated by wet sieving method, Emerson method, mechanical and chemical dispersion method, and LeBissonnaia method. The numbers and stability of soil aggregates were evaluated with> 0.25mm water Stable Aggregate Content (WSA), Aggregate Average Weight Diameter (MWD), and Aggregate Damage Rate (PAD). The results showed that there was a significant positive correlation between the MWD values measured by the three methods. The quantity and stability of soil aggregates were closely related to the land use patterns. The forest land and the garden land were the highest, and the wasteland and parent material were the lowest. The MWD of ~ 0.5mm aggregates showed WS> SW> FW and the relative dissipation coefficient (RSI) was 31% after wetting (FW), slow wetting (SW) and prewetting (WS) ~ 45%, indicating that the main physical mechanism of aggregate disintegration is the dissipation effect caused by occluded air in the aggregates. The three methods are comparable and reflect the characteristics of soil aggregates and the stability mechanism. The amount of aggregates and the stability index can be used as an important index to measure soil quality and corrosion resistance.