Soils with Lamellae - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 288

Table 24.6 Relation between soil taxa criteria and characteristics of lamellae and the E & Bt
horizon (Bockheim and Hartemink 2013 ) a

Thick. E
&Bt
(cm)

Soil taxa
criteria

Number
of pedons

Min. thick.
lamella (mm)

Max. thick.
lamella (mm)

Depth surface
E & Bt (cm)

Depth base
E & Bt (cm)

Texture class
Loamy

49 7a 18b 55b 126b 71b

Silty 7 4a 34a 35c 89c 54a

Sandy 71 6a 23b 87a 180a 94a

P value 0.711 0.036 0.001 0.001 0.003

< <

Soil-moisture regime
Udic

57 6a 22a 79a 170a 91a

Ustic 33 7a 19a 64a 133b 69b

Xeric 11 5a 28a 59a 149ab 90ab

P value 0.834 0.312 0.103 0.021 0.038

Soil-temperature regime
Frigid

40 7a 25ab 70bc 149b 79b

Cryic 37 5a 13b 41d 113c 71ab

Mesic 28 6a 26a 81b 171ab 90ab

Thermic 17 7a 20ab 105ab 208a 103a

Hyperthermic 3 3a 14ab 140a 231a 91ab

P value 0.769 0.059 0.001 0.001 0.089

< <

Soil order
Alfisols 39 8a 28a 59b 133b 74b

Entisols 40 7a 24a 84a 177a 93ab

Inceptisols 25 4a 10b 54b 123b 69b

Spodosols 9 3a 15ab 106a 227a 121a

Ultisols 4 7a 29ab 120a 198ab 78ab

P value 0.001 0.007

a Values within a class-column with differences in small-case letters are statistically different based
on pairwise t-tests

0.285 0.004 0.001

< <

Holliday and Rawling 2006 ). The lack of pedoturbation may be important to the
development of textural bands (Kemp and McIntosh 1989 ; Johnson et al. 2008 ), but
they may also degrade with time due to pedoturbution or changes in the biogeo-
chemistry in the soil profile.
Topography is of regional importance in the occurrence and formation of
lamellae. In IA, lamellae are found predominantly in areas with 10 % slopes,

and depressions in the landscape may have thicker and shallower lamellae than
upland areas in the middle-Atlantic states (Folks and Riecken 1956 ). Whereas
Robinson and Rich ( 1960 ) reported that lamellae in VA soils do not conform to
the surface relief, Folks and Riecken ( 1956 ) and Coen et al. ( 1966 ) showed that they
do mirror surface relief in IA and Alberta, Canada (Table 24.5 ). It appears that
topography plays a hard to define role in the presence and formation of lamellae.
Climate is important in the development of soils with lamellae and the depth and
thickness of the lamellic zone more or less follows: udic

<

ustic, xeric; and

>