应用Le Bissonnais法测定富铁土中团聚体的稳定性及其意义

Le Bissonnais Method of Measuring Aggregate Stability in Ferrisols and Its Implications

土壤团聚体的数量和稳定性是衡量土壤抗蚀性和土壤质量的重要指标,应用LeBissonnais法对富铁土团聚体的稳定性和物理学机制进行了研究。结果表明,LeBissonnais法测定的团聚体平均重量直径(MWD)与常规湿筛法测定的>0.25mm团聚体含量、MWD和>2mm团聚体破坏率(PAD)呈极显著正相关。富铁土中5～2,2～1,1～0.5mm团聚体经快速湿润(FW)、慢速湿润(SW)和预湿后扰动(WS)处理后,稳定性团聚体的粒级分布随处理方式和初始团聚体大小的不同而不同;经FW处理后,大多数团聚体崩解;团聚体崩解产物的MWD表现为FW<SW<WS,表明富铁土团聚体崩解的主要机制是由于团聚体内部的闭塞空气产生的压力引起的,其次是黏粒的膨胀作用。富铁土团聚体的数量和稳定性指标均与有机质含量呈显著正相关,表明有机质是影响富铁土团聚体形成和稳定的主要胶结物质。团聚体MWD与黏粒含量呈显著负相关,而与氧化铁含量没有显著相关性。

The measurement of aggregate stability is often used as indices of charactering soil anti-erodibility and soil quality. The sensitive aggregate stability test, Le Bissonnais method, was used to assess aggregate stability and its breakdown mechanisms of Ferrisols in the present study. The measured aggregate stability indices by Le Bissonnais method were highly significantly linearly correlated with the aggregate amount with 0.25 mm in diameter, mean weigh diameter (MWD) and percentage of aggregate disruption determined by conventional wet sieving method. The aggregate size distribution (ASD) of dry 5~2 mm, 2~1 mm, and 1~0.5 mm aggregates after fast wetting (FW), slow wetting (SW) and wet-stirring (WS) treatments was significantly affected by treatment method and initial aggregate size. The FW treatment had the largest aggregate disruption, while WS treatment had the lowest aggregate disruption. It suggested that the aggregate breakdown in the Ferrisols was mainly caused by the entrapped air pressure in the soil porosity and clay different swelling when fast wetting. There was a significant relation between >0.25 mm aggregate content and organic matter, and similarly between aggregate MWD and organic matter. Results showed that the organic matter is the main cementing and stabilization agent of aggregate formation in the Ferrisols. The aggregate stability indices in the Ferrisols were significantly negatively related to clay content, and no relationships between aggregate stability and free iron content were been found.