State Soils

Just as many states have official state flowers, birds, and fossils, they also have official soils. State soils are most often determined by a vote of soil scientists in the state, and, absent any political wrangling, usually represent the most productive soils and those that most closely resemble everyone’s favorite soil: loam. As mentioned earlier, loam soils are almost equal parts sand, silt, and clay.


The state soil of Idaho is the Threebear series. A type of Andisol, it is formed from silt and volcanic ash, resulting in a silty loam. These soils are found on hill slopes with a 5% to 35% grade and are associated with timber production.


Scobey soils are Mollisols that are found in north-central Montana and cover more than 280,000 hectares (700,000 acres) of till plains and moraines. These soils consist of brown clay loam and are ideal for growing wheat, which dominates the region’s agriculture.


In south-central Nebraska, Holdrege soils cover nearly 810,000 hectares (two million acres) of land and support cropland and rangeland. These Mollisols formed from calcareous and silty loess material, and commonly support crops of soybeans, corn, and wheat.

North Dakota

The state soil of North Dakota is the Williams series, light gray to brown loamy Mollisols. These soils are widely found throughout the state on more than 810,000 hectares (two million acres) of land. Hilly areas of this soil are used for grazing, while level areas are used to produce flax, sunflowers, barley, oats, and wheat.

South Dakota

Houdek soil, a deep, loamy Mollisol, is the state soil of South Dakota. Found throughout the East River area of South Dakota, this grassland soil is heavily developed for agricultural purposes.


Forkwood soils are brown, clay loam Aridisols that are derived from the slopewash alluvium of shales and sandstone. These soils are primarily used for wildlife or grazing livestock.