http://www.greenbook.net/docs/ProdSum/P45185.PDF

Soil with large cracks are called “vertic soils”, and experience extreme changes in key soil properties throughout the year


http://www.itc.nl/~rossiter/research/nsm/nsm_smr.html

2. In the horizons that have aquic conditions, enough active
ferrous iron to give a positive reaction to alpha,alphadipyridyl
at a time when the soil is not being irrigated.
Aqualfs, p. 35
JB. Other Alfisols that have a cryic or isofrigid temperature
regime.
Cryalfs, p. 44
JC. Other Alfisols that have an ustic moisture regime.
Ustalfs, p. 59
JD. Other Alfisols that have a xeric moisture regime.
Xeralfs, p. 71
JE. Other Alfisols.
Udalfs, p. 47




Other Aqualfs that have episaturation.
Epiaqualfs,

3. Saturation: A horizon is saturated when the soil water pressure is zero or positive.a. Water will run into an unlined auger hole or a piezometer when the horizon is saturated.b. Saturation may occur at any time of the year, not simply during the growing season as is required for jurisdictional wetlands.c. Saturation is not required if the soils are artificially drained.d. Three kinds of saturation have been defined:
i) Endosaturation-soil is saturated in all horizons that lie between the upper boundary of saturation and a depth of 2 m.
ii) Episaturation-soil is saturated in a horizon that overlies an unsaturated horizon, wherer the unsaturated horizon lies within a depth of 2 m from the surface.
iii) Anthric saturation-similar to episaturation but is used for sites having controlled flooding.

http://soils.usda.gov/technical/classification/orders/alfisols_map.html

Order Suborder
Greatgroup
Subgroup
Alfisols(3.8;0.2)


Udalfs(3.8;0.2)
Hapludalfs(3.8;0.2)
Typic Hapludalfs(3.8;0.2)


Alfisols are extensive in the United States. They make up about 13.9 percent of the surface area. In normal years water they are dry when the soils are warm enough for plants to grow.

Dominant Suborders

Udalfs
Udalfs, which have a udic moisture regime, are of large extent in the United States. They form a belt extending from Minnesota through Wisconsin, Michigan, Indiana, and Ohio and ending in New York State. Another large area of Udalfs begins in southern Iowa and extends through Missouri, Illinois, and the States to the south bordering the Mississippi River. All Udalfs are believed to have supported forest vegetation at some time during development.

Aqualfs
Aqualfs, which have warm and aquic conditions, primarily are found in an area bordering the southern part of the Mississippi River, in southern Illinois, and in Indiana and Ohio. Most Aqualfs have some artificial drainage or other water control and are used as cropland for corn, soybeans, and rice. Nearly all Aqualfs are believed to have supported forest vegetation in the past.