Albic Horizon - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 82

Table 10.2 (continued)
Order Suborder Great group Subgroups Total

Orthods Alorthods Arenic (2), Entic (1), Entic Glossarenic (7),

Glossarenic (1), Oxyaquic (15), Typic (1)

27

Durorthods Andic (2), Typic (10) 12

Fragiorthods Alfic (7), Alfic Oxyaquic (10), Aquic (2), Entic (1),
Oxyaquic (5), Typic (3), Ultic (1)

29

Haplorthods Alfic (32), Alfic Oxyaquic (30), Andic (6), Aqualfic
(3), Aquentic (6), Aquic (29), Entic (29), Entic
Lithic (1), Fragic (3), Lamellic (9), Lamellic
Oxyaquic (2), Lithic (12), Oxyaquic (34),
Oxyaquic Ultic (2), Typic (74)

272

Placorthods Typic (1) 1

676

Ultisols Aquults Albaquults Kanidic (1), Typic (12) 13

Total 872

10.4 Distribution of Soils with an Albic Horizon

The total area of soils with albic horizons is estimated to be 355,869 km 2 , or about
3.9 % of the total area of the USA. The Spodosols account for approximately 82 %
of these soils (Fig. 10.2 ).

10.5 Factors Influencing the Development of the Albic
Horizon

Aquic conditions appear to be a key factor in the development of albic horizons in
the Aqualfs, Aquods, and Aquults as soil series in these suborders comprise 25 % of
the of the soil series with an albic horizon (Table 10.3 ).

10.6 Genesis of the Albic Horizon

The albic horizon originates from intense leaching of clays and Fe oxyhydroxides,
yielding a bleached (bleicherd Ge.) horizon with low chromas and values. The albic
horizon in Albolls has long puzzled pedologists as this horizon occurs beneath a
dark-colored, base-rich mollic epipedon. It would seem that a change in climate
resulted in conversion of deciduous forest into grassland vegetation with a mollic
epipedon forming in the upper part of the albic horizon.