Tama -- Iowa State Soil

Photograph of landscape of Tama soil series.

Photograph of a profile of a typifying pedon of Tama soil series.

Tama Soil Profile

Surface layer:  very dark brown silty clay loam
Subsurface layer:  very dark grayish brown silty clay loam
Subsoil - upper:  brown silty clay loam
Subsoil - lower:  dark yellowish brown silty clay loam
Substratum:  yellowish brown silty clay loam

The Tama series is considered one of the most productive of the soils in Iowa that are used for agricultural purposes. It makes up about 825,000 acres in east-central and eastern Iowa. The series was first identified in Black Hawk County, Iowa, in 1917. It has been identified in 26 counties in Iowa. It also has been identified in Illinois, Minnesota, and Wisconsin.

Tama soils formed in 48 or more inches of silty loess; under tall prairie grasses with a deep, fibrous root system; and under relatively humid climatic conditions. Over hundreds of years, the grasses have added organic matter to the soils, producing a relatively thick, dark surface layer. In some areas, erosion has significantly affected the properties of the soils. Eroded Tama soils have less total nitrogen and organic matter and more clay in the surface layer than uneroded Tama soils.

Small scale map of Iowa and nearby states showing distribution of Tama soil series.

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