page_title: Ultisol
section_title: Gardening in Ultisol
hierarchical_section_title: Ultisol / Gardening in Ultisol
caption_attribution_description: English: Ground covered with mulch of crushed wood. Picture taken in Belgium. Français&#160;: Sol recouvert d'un paillage de bois broyé. Photo prise en Belgique.
context_page_description: Ultisols, commonly known as red clay soils, are one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continuous weathering of minerals in a humid, temperate climate without new soil formation via glaciation. They are defined as mineral soils which contain no calcareous material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer of soil, and have less than 35% base saturation throughout the soil. Ultisols occur in humid temperate or tropical regions. 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, and South America.
  In the World Reference Base for Soil Resources, most Ultisols are known as Acrisols and Alisols. Some belong to the Retisols or to the Nitisols. Aquults are typically Stagnosols or Planosols. Humults may be Umbrisols.
context_section_description: The lack of organic matter in Ultisol makes it difficult for plants to grow without proper care and considerations. Soil amendments are generally required each year in order to sustain plant life in regions with primarily Ultisol soil. The use of soil tests, coupled with the corresponding provisions, can alleviate issues of nutrition and irrigation that can result from non porous Ultisol. Soil tests help indicate the pH, and red clay soil typically has a low pH. The addition of lime is used to help to increase the pH in soil and can help increase the pH in Ultisol as well.
  Clay soil is known to retain nutrients very well because its negative charge helps to attract cations. As a result, Ultisol does not often require the high amounts of fertilizer additions other types of soils often do. However, this retention of nutrients coincides with a lack of water filtration that may subject plants to highly saturated soil. Not all plants can survive in the moist, humid Ultisol found throughout the Southeastern United States and elsewhere.
caption: Mulch can be used to help improve Ultisol
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