While the term is usually applied to the red clay soils of the Southern United States, Ultisols are also found in regions of Africa, Asia, Australia and South America.
[1] Ultisols vary in color from purplish-red, to a bright reddish-orange, to pale yellowish-orange and (in cooler areas such as Pennsylvania) even some subdued yellowish-brown or grayish-brown tones.
Major nutrients, such as calcium and potassium, are typically deficient in Ultisols,[2] which means they generally cannot be used for sedentary agriculture without the aid of lime and other fertilizers, such as superphosphate.
Ultisols are the dominant soils in the Southern United States (where the Cecil series is most famous), southeastern China, Southeast Asia, and some other subtropical and tropical areas.
Though known from far north of their present range as recently as the Miocene, Ultisols are surprisingly rare as fossils overall, since they would have been expected to be very common in the warm Mesozoic and Tertiary paleoclimates.
[3] The use of soil tests, coupled with the corresponding provisions, can alleviate issues of nutrition and irrigation that can result from non porous Ultisol.
[8] The use of mulch is widespread in the Piedmont region of the United States as a solution to the high temperatures and saturation of the soil.
[17] The Missouri Botanical Garden recommends tickweed, spotted jewelweed, mealycup sage, Camassia, spring starflower, ostrich fern, sideoats grama, Bouteloua curtipendula, and prairie dropseed.