When downloading soils information from the Soil Data Mart:
Be sure to access both the spacial and tabular information at the Soil Data Mart.
If only the spatial information is downloaded, all you will be able to symbolize are map unit names. If the tabular data is joined to the soil layer there are an endless number of properties that can be symbolized.
In addition, soil tabular data can be modeled using a combination of soil properties and is an important part of many models used for land use planning.