University of Idaho College of Agricultural and Life Sciences Plant, Soil & Entomological Sciences Soil & Land Resources
Soil Orders
Soil Links
  Gelisols    Histosols    Spodosols    Andisols    Oxisols    Vertisols    Aridisols    Ultisols    Mollisols    Alfisols    Inceptisols    Entisols

Mollisols (from Latin mollis, "soft") 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.

Click on map to view larger image

Click on map to view larger image
1. Typic Endoaquoll
2. Argialboll
South Dakota
3. Typic Argiudoll
4. Udoll-Aquoll landscape
central Iowa
5. Typic Argiustoll
southeastern South Dakota
6. Rendoll
7. Cryoll landscape
Lemhi Co., ID
8. Pachic Argicryoll
Lemhi Co., ID
9. Argixeroll landscape
Nez Perce Co., ID
10. Lithic Argixeroll
Nez Perce Co., ID
11. Haploxeroll landscape
Teton Co., ID
12. Calcic Haploxeroll
Teton Co., ID
13. Haploxeroll landscape
Latah Co., ID
14. Pachic Ultic Haploxeroll
Latah Co., ID
15. Argixeroll landscape
Benewah Co., ID
16. Oxyaquic Argixeroll
Benewah Co., ID
If you have any comments, suggestions, or questions about the 12 Soil Orders web site,
please contact
Dr. Paul McDaniel  at the Soil Science Division,
University of Idaho, Moscow, ID 83844-2339.