Fragipan Horizon - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 153

15.3 Classification of Soils with Fragipans

From the NRCS dataset, 362 soil series with fragipans in the USA were identified.
They particularly occur in Alfisols (160 soil series) and Ultisols (117 soil series) and
to a lesser extent in Inceptisols (53 soil series) and Spodosols (32 soil series)
(Table 15.2 ). Soils with fragipans are identified in 11 great groups and 20 subgroups.
The soils containing fragipans occur primarily in the fine-silty (111 soil series),
fine-loamy (88), and coarse-loamy (66 soil series) (total 73 %) particle-size

classes (Fig. 15.2 ). Only seven soil series were assigned to sandy or sandy-skeletal
particle-size classes. More than 80 % of the fragipan soils occur in the mixed
mineral class and have an udic soil-moisture regime. Sixty percent of the soil series
have a mesic soil-temperature regime, with the remaining series equally divided
between frigid and thermic.

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Table 15.2 Classification of soils with fragipans in the USA (Bockheim and Hartemink 2013 )

No. of soil
series Order Suborder Great groups Subgroups Common soil series

Alfisols Aqualfs Epiaqualfs Aeric Fragic 2 Bromer, Hatfield

Fragic 2

Endoaqualfs Aeric Fragic 1 Bluford

Fragiaqualfs Aeric 16 Grenada, Venango

Typic 13 Henry

Vermic 1

Glossaqualfs Aeric Fragic 1 Avonburg

Fragic 2

Udalfs Fragiudalfs Andic 2

Aquic 28 Canfield, Rossmoyne

Oxyaquic 44 Ava, Cincinnati, Hosmer,

Loring,
Nicholson, Providence,
Zanesville,
Jonca, Hildebrecht, Crelden

Typic 7

Vitrandic 2

Fraglossudalfs Aquic 8 Calloway

Oxyaquic 5 Sadler

Glossudalfs Fragiaquic 1

Fragic 3

Hapludalfs Fragiaquic 6

Fragic 1

Fragic
Oxyaquic

5

Paleudalfs Fragiaquic 4

Fragic 1

(continued)