Lower Depths of Horizons and Boundaries

Lower Depths of Horizons and Boundaries

The depth of the lower boundary as measured from the soil surface should be recorded in centimeters (cm).  Alternately, the depth of both the upper and lower boundary may be given, but only the depth to the lower boundary will be graded.  For example, a Bt1 horizon occurring from 30-45 cm may be recorded as “45 cm” (preferred) or “30-45 cm”.

Depth measurements should be made between the tapes in the restricted area on the pit wall using the mounted tape measure provided.  A range for the lower depth considered correct will be based on the boundary’s distinctness according to Table 3. Where one horizon grades into another, the location of the boundary will be specified at the bottom of the transition zone.

The transition will be part of the overlying horizon for the Region IV SASES[1] land judging.

No horizon less than 8 cm thick will be described.  If a horizon less than 8 cm thick occurs, it should be combined with the adjacent horizon that is most similar for the depth measurement purposes.  When two horizons combine to a total thickness of 8 cm or more, the properties of the thicker horizon should be described.  If lamellae are encountered that are thinner than 8 cm, then the convention is to describe the eluvial and illuvial horizons as a unit (i.e., E&Bt) and the thickest horizon’s morphology would be described.

[1]Students of Agronomy, Soils, and Environmental Sciences

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