Ultisols

As Ultisol is called according to the USDA soil classification forest soils of the tropics and subtropics, which are highly acidic due to intensive weathering and leaching. They are found particularly in the southeastern parts of the U.S., Central America, Brazil and Argentina, West and Central Africa, Southeast Asia and parts of Korea, Japan and Northeast of Australia and have usually formed over a relatively long period of time.

Typical of Ultisole is a thin yellowish -colored A horizon near the surface, beneath which a deep red colored by iron oxides B horizon is.

Agriculture are Ultisole only after intensive fertilization usable, since most of the nutrients have been spent by the weathering in deeper soil layers. The low pH - value must also be neutralized by addition of lime. From forest view Ultisole be assessed, however, to be very productive.

Worldwide, about 11 million square kilometers of land of Ultisolen are covered, representing 8.5 percent of the ice-free land surface.

Classification

We divide Ultisole in five suborders:

• Aquult
• Humult
• Udult
• Ustult
• Xerult