Australian Ultisol-2

Australian Ultisol-2

Here is another deeply weathered Ultisol from Australia. It is similar in some ways to the deeply weathered Ultisol from lecture 5. One significant difference is that it is found nearer the coast under much higher rainfall. Thus, soil scientists have concluded that it must be much younger than the soil formed under much lower precipitation. This soil is red, indicating much iron oxide has been generated by the weathering of primary minerals. It is about 2 m deep to bedrock. A moderately thick A horizon can be seen near the shovel handle. Below is a red zone of clay accumulation. The zone of maximum clay accumulation is found along the length of the shovel. In this profile, the clay content slowly declines. The blade of the shovel is still in one of many Bt horizons. An Ultisol must have more clay in the subsoil than the surface horizon and it must have base saturation at depth of less than 35%. The base saturation requirement separates Ultisols from Alfisols. Ultisols are more highly weathered than Alfisols.

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