USDA soil taxonomy

As a USDA soil classification refers to a classification of soils, the U.S. Department of Agriculture ( U.S. Department of Agriculture, USDA - Natural Resources Conservation Service, NRCS ) has published. It represents next to the FAO soil classification and World Reference Base one of the most important in use worldwide classification systems for floors

The USDA classification divides soils on the climate zone and typical vegetation into twelve orders, which are given below:

• Alfi sols are forest soils of temperate latitudes with low-lying layer of clay. They are formed from regions with a humid climate.
• Andi sols are volcanic soils that develop from ashes and are characterized by a high content of volcanic glasses.
• Aridisole are alkaline desert soils of tropical and temperate latitudes, which form in regions of hot, dry climate.
• Entisole are very young soils with no discernible layers. This category will be assigned to all soil types that can be assigned to any of the other orders.
• Gelisole are found exclusively in the northern polar region and in the high mountains. They are characterized by permafrost in less than two meters deep.
• Histosols are highly carbonaceous soils of the temperate latitudes. They are formed in cold -wet climate, particularly if the natural drainage is poor.
• Inceptisole are young soils with very weak distinctive vertical profile, which can be found both in temperate latitudes and in the tropics.
• Molli sols are grass-covered soils of temperate latitudes.
• Oxisole are strongly acid soils of the tropics, which are often colored red due to weathering.
• Spodosole are mostly coniferous forest vegetated, acidic soils of temperate regions, which have been formed of coarse-grained starting material. They are found primarily in regions with cold damp climate.
• Ultisole are highly weathered tropical and subtropical forest soils. By leaching they are usually very acidic.
• Vertisols are soils of the tropics and temperate latitudes, which are characterized by a high clay content. This can form deep soil columns at dryness.

The orders received will be further divided into sub- systems over groups and subgroups, families and series; the fine systematics can be found in the respective articles.