Order:
Suborder:
[ ]
| Code |
Name |
Description |
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Ustolls that have a duripan that has its upper boundary within 100 cm of the mineral soil surface. |
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Other Ustolls that have a natric horizon. |
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Other Ustolls that:
- Have either a calcic or gypsic horizon that has its upper boundary within 100 cm of the mineral soil surface or a petrocalcic horizon that has its upper boundary within 150 cm of the mineral soil surface; and
- Do not have an argillic horizon above the calcic, gypsic, or petrocalcic horizon; and
- In all parts above the calcic, gypsic, or petrocalcic horizon, after the materials between the soil surface and a depth of 18 cm have been mixed, either are calcareous or have a texture of loamy fine sand or coarser.
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Other Ustolls that have either:
- A petrocalcic horizon that has its upper boundary within 150 cm of the mineral soil surface; or
- An argillic horizon that has one or both of the following:
- With increasing depth, no clay decrease of 20 percent or more (relative) from the maximum clay content (noncarbonate clay) within 150 cm of the mineral soil surface (and there is no densic, lithic, or paralithic contact within that depth); and either
- Hue of 7.5YR or redder and chroma of 5 or more in the matrix; or
- Common redox concentrations with hue
of 7.5YR or redder or chroma of 6 or more, or
both; or
- 35 percent or more clay in its upper part and a clay increase either of 20 percent or more (absolute) within a vertical distance of 7.5 cm or of 15 percent or more (absolute) within a vertical distance of 2.5 cm, in the fine-earth fraction (and there is no densic, lithic, or paralithic contact within 50 cm of the mineral soil surface).
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Other Ustolls that have an argillic horizon. |
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Other Ustolls that have a mollic epipedon that:
- Either below an Ap horizon or below a depth of 18 cm from the mineral soil surface, contains 50 percent or more (by volume) wormholes, wormcasts, or filled animal burrows; and
- Either rests on a lithic contact or has a transition zone to the underlying horizon in which 25 percent or more of the soil volume consists of discrete wormholes, wormcasts, or animal burrows filled with material from the mollic epipedon and from the underlying horizon.
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Other Ustolls. |
Source:
Keys to Soil Taxonomy, Eighth Edition. 1998.
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