Key to Great Groups
CAC. Other Aquods that have a fragipan with its upper boundary within 100 cm of the mineral soil surface. Fragiaquods, p. 704
CAC. These are the Aquods that have a fragipan below the spodic horizon, normally at a depth of 40 to 75 cm below the mineral soil surface. Plant roots are shallow, and the soil clinging to the roots of falling trees has in many areas developed a microrelief of 20 to 50 cm. The soil temperature regime is normally frigid. These soils are nearly level, but few of them are cultivated, except for those used for the production of hay. Most of the soils are forested. Fragiaquods are not extensive in the United States.
Fragiaquods are the Aquods that:
1. Have a fragipan with its upper boundary within 100 cm of the mineral soil surface;
2. Have 0.10 percent or more iron (by ammonium oxalate) in 75 percent or more of the spodic horizon; and
3. Do not have a cryic temperature regime.
Key to Subgroups
CACA. Fragiaquods that have a histic epipedon. Histic Fragiaquods
CACB. Other Fragiaquods that have a surface horizon 30 cm or more thick that meets all of the requirements for a plaggen epipedon except thickness. Plagganthreptic Fragiaquods
CACC. Other Fragiaquods that have an argillic or kandic horizon within 200 cm of the mineral soil surface. Argic Fragiaquods
CACD. Other Fragiaquods. Typic Fragiaquods
Definition of Typic Fragiaquods
Typic Fragiaquods are the Fragiaquods that:
1. Do not have a histic epipedon;
2. Do not have a surface horizon more than 30 cm thick that meets all of the requirements for a plaggen epipedon except thickness; and
3. Do not have, within 200 cm of the mineral soil surface, an argillic or kandic horizon that has a base saturation of 35 percent or more (by sum of cations) in any part.
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