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

Histosols (from Greek histos, "tissue") are soils that are composed mainly of organic materials. They contain at least 20-30% organic matter by weight and are more than 40 cm thick. Bulk densities are quite low, often less than 0.3 g cm3.

Most Histosols form in settings such as wetlands where restricted drainage inhibits the decomposition of plant and animal remains, allowing these organic materials to accumulate over time. As a result, Histosols are ecologically important because of the large quantities of carbon they contain. These soils occupy ~1.2% of the ice-free land area globally and ~1.6% of the US.

Histosols are often referred to as peats and mucks and have physical properties that restrict their use for engineering purposes. These include low weight-bearing capacity and subsidence when drained. They are mined for fuel and horticultural products.

Histosols are divided into 5 suborders: Folists, Wassists, Fibrists, Saprists, and Hemists. 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
<< back to Soil Orders list Histosol example #1 >> 
1. Histosol landscape
North Carolina
2. Limnic Haplosaprist
southern Michigan
3. Haplosaprist landscape
northern Idaho
4. Typic Haplosaprist
northern Idaho
5. volume change
in drained organic material
6. subsidence in drained Histosol
Everglades, Florida

7. use of Histosol for fuel

8. Lithic Torrifolist
southern Idaho
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.