Ultisols

Ultisol Soils

Ultisols are the dominant soil type found in the southern forest. The "red clay" soils of the southeastern United States are examples of Ultisols. These soils are generally formed under forest canopy, explaining why they are the dominant forest soil in the south. Iron and aluminum are constantly being leached from the soil surface into the subsoil below often resulting in the lighter coloring at the soil surface and the strong yellowish or reddish colors at the lower horizons. Subsoils also tend to be stiffer due to the downward movement of iron in the soil (Walker and Oswald 2000). Ultisols are acidic in nature and quite productive under good management (Brady and Weil 1999). However, high acidity and relative low availability of calcium, magnesium, and potassium render these soils poorly suited for continuous agriculture without the use of fertilizer and lime.