Environmental Engineering Reference
In-Depth Information
Fig. 4.13 Two hydric soils. The soil on the
left meets
Field Indicator S7 Dark Surface. The soil on
the
right meets
Field Indicator F3 Depleted Matrix (Published with kind permission of US
Department of Agriculture, Natural Resources Conservation Service (
2010a
). Figure is public
domain in the USA. All Rights Reserved)
example is a soil that meets all the requirements of F3 Depleted Matrix, but the
layer that meets the requirements starts below 15 cm (6 in.) and the matrix chroma
above the layer is a chroma
2. While the soil does meet all the specific
requirements of the Field Indicator, it fails the rule that any soil material above
the indicator must have a matrix chroma
>
2 or, if the matrix chroma is
2 it must
>
be
15 cm thick.
It is helpful for the practitioner to review the Corps Regional Supplement for
the geographic area in question and identify those Field Indicators applicable in
their LRR or MLRA. It may also be helpful to create a one page cheat sheet of the
Field Indicators that only lists the indicator descriptions for those identified for the
region in question. However, when learning to use the Field Indicators it is helpful
to have the user notes and glossary handy for referral when attempting to use a Field
Indicator. The sheer number of Field Indicators that that can be used in a region can
be intimidating to the novice. However, with experience, the practitioner will find
that a small number of them are used for the majority of hydric soil identifications.
The remainder of Field Indicators are used in areas that are obviously wet and not
near the hydric soil boundary or for areas or specific situations that did not have
commonly used Field Indicators. Nationwide, the commonly used Field Indicators
are A11 Depleted Below Dark Surface, F3 Depleted Matrix (Fig.
4.13
), F6 Redox
Dark Surface, S5 Sandy Redox, and S7 Dark Surface (Fig.
4.12
).
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