Environmental Engineering Reference
In-Depth Information
3. The Field Indicators were developed to locate the hydric soil boundary. Wetter
soils may not meet a Field Indicator.
4. Depths and thicknesses are critical in the upper 30-45 cm (12-18 in.) of the soil
when using the Field Indicators. It is recommended that a spade, not an auger,
be used to excavate the soil.
5. All soil (A) indicators can be used in any layer regardless of texture. Sandy soil
(S) indicators can be used in layers that are loamy fine sand or coarser. Loamy
and clayey (F) indicators can be used in layers that are loamy very fine sand and
finer.
6. Layers are not synonymous with horizons. One horizon may consist of multiple
layers or one layer may include multiple horizons.
7. If a soil meets all the requirements of multiple indicators except thickness, you
can combine indicators by adding up the thicknesses of each layer that meets
the requirements. You can then designate it as hydric if the thickness is as thick
as the most stringent thickness requirement of the indicators it meets (see an
explanation of this in the introductory information in Chapter 3 of your regional
supplement for a more thorough explanation).
8. Chromas should not be rounded. If the chroma appears to be between color
chips, indicate that by using a + or a decimal point. Some indicators require a
chroma of x or less. Others require a chroma less than x. In the former, if the
color is between the required chroma and a higher chroma, it does not meet the
requirement. In the latter, if the color is between the listed chroma and the next
lower chroma, it does meet the requirement.
9. In LRRs R, W, X, and Y, observations begin at the top of the mineral surface
(underneath any and all fibric, hemic, and/or sapric material) except for appli-
cation of indicators A1, A2, and A3, where observations begin at the actual soil
surface. In LRRs F, G, H, and M, observations begin at the actual soil surface if
the soil is sandy and for the application of indicators A1, A2, and A3; and at the
muck or mineral surface for the remaining Field Indicators. In the remaining
LRRs, observations begin at the top of the muck or mineral surface (underneath
any fibric and/or hemic material) except for application of indicators A1, A2,
and A3 where observations begin at the actual soil surface.
10. Except for indicators A16, S6, S11, F8, F12, F19, F20, and F21 (those
indicators that do not require a chroma
2 to meet the indicator), any soil
material above the indicator must be a chroma
2 or if the chroma is
2 it must
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be less than 15 cm (6 in.) thick.
11. Both the definition of a depleted matrix and a gleyed matrix require values
4.
This is to separate redox colors from organic matter accumulation colors. A, E
and calcic horizons require
2 % concentrations.
12. Remember to describe organic features such as type (peat, mucky peat, or peat),
color, mucky modified mineral, and percent masking of sand grains.
It is critical that the practitioner be familiar with the general rules required for
using the Field Indicators. There are situations where a soil may meet all the
requirements of the Field Indicator, however, it is not a hydric soil based on that
Field Indicator because it has failed one of the general rules. The most common
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