Soils with Lamellae - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 275

24.2 Properties of Soils with Lamellae

Official Soil Descriptions distinguish lamellae from an interlamellar horizon in
several ways: (1) as “E and Bt” or “E & Bt” horizons, (2) as an E/Bt, or (3) as
being contained within a Bt horizon. Based on data from 118 pedons, the thickness of
a lamella varied from 6 to 22 mm (Table 24.1 ). The mean depth to the first lamella
was 72 cm, and the mean depth to the lowermost lamella exceeded 155 cm, yielding
an average thickness of over 83 cm for the lamellic zone. However, the total thickness
of the lamellae was less than 15 cm as required for the soil to be classified as lamellic
and not cambic or argillic. The number of lamellae normally in the upper 150 cm
ranged from 1 to 16 and averaged 8. Lamellae were often continuous but may exist
discontinuously as segments; they may have wavy, irregular, or broken boundaries.
Two soil series from WI containing lamellae are shown in Figs. 24.1 and 24.2 .
Lamellae in the Spinks soil series were found at 40 cm until 200 cm depth. The soil
is a sandy, mixed, mesic Lamellic Hapludalfs (Fig. 24.1 ). The lamellae at 40-50 cm
were less than 2 mm thick and slightly finer than the interlamellae soil textures.
Lamellae in the Oshtemo soil series occurred below 185 cm depth (Fig. 24.2 ). The
soil is a coarse-loamy, mixed, active, mesic Typic Hapludalfs. The lamellae at that
depth were several centimeters thick and slightly finer than the interlamellae soil
textures. The total thickness of the lamellae exceeded 15 cm so that the soil was
classified as Typic rather than Lamellic.
The lamellae (Bt portion of horizon) of the OSDs most commonly have a loamy
sand (33 %), loamy fine sand (33 %), or sandy loam (29 %) texture and are usually
one textural class finer than the associated E part of the horizon (Table 24.2 ). Clay
bridging of sand grains was reported in 46 (39 %) of the Official Soil Descriptions
with lamellae, and argillans were recorded in 29 (25 %) of the pedons (Table 24.1 ).
The mean clay concentrations for the Bt lamellae and E interlamellae were 8.6
and 2.8 %, respectively (Table 24.3 ). The cation-exchange capacity and extractable
Fe were greater in the Bt than in the E, the organic C and pH were higher in the E
than in the Bt, and the base saturations were comparable between the two horizons.
There were insufficient data to statistically compare other physical and chemical
properties of the lamellar and interlamellar horizons.

Table 24.1 Characteristics of lamellae from Official Soil Descriptions (Bockheim and Hartemink
2013 a)
Property Mean St. error

Minimum lamella thickness (mm) 6.5 0.82

Maximum lamella thickness (mm) 22 1.8

Depth to uppermost lamella (cm) 72 3.9

Depth to lowermost lamella (cm) 155 6.1

Thickness of lamellic zone (cm) 83 4.0

Number of lamellae 8 0.87

Proportion of OSD reporting clay bridging (%) 39 -

Proportion of OSD reporting coated sand grains (%) 25 -