Mollisols are the soils of grassland ecosystems. They are characterized by a thick, dark surface horizon. This fertile surface horizon, known as a mollic epipedon, results from the long-term addition of organic materials derived from plant roots.

Mollisols primarily occur in the middle latitudes and are extensive in prairie regions such as the Great Plains of the US. Globally, they occupy ~7.0% of the ice-free land area. In the US, they are the most extensive soil order, accounting for ~21.5% of the land area.

Mollisols are among some of the most important and productive agricultural soils in the world and are extensively used for this purpose.

Mollisols are divided into 8 suborders: Albolls, Aquolls, Rendolls, Gelolls, Cryolls, Xerolls, Ustolls, and Udolls. Click here for more information about these suborders. Click here to view a map of their distribution in the US.