Environmental Engineering Reference
In-Depth Information
Answers
Sampling point 1: This description meets A11 Depleted Below Dark Surface, F3
Depleted Matrix, and F6 Redox Dark Surface.
Sampling point 2: No indicator is met. Note that this description would meet F3
Depleted Matrix. However, it fails the general rule that you cannot have 15 cm (6 in.)
or more of a matrix chroma higher than 2 above the depleted matrix (indicator).
Sampling point 3: F8 Redox Depressions. Note that this is one of the landscape
specific indicators that allows matrix chromas higher than 2. In this case, it can only
be used in soils that occur in closed depressions subject to ponding. Examples are
vernal pools, playa lakes, rainwater basins, “Grady” ponds and potholes.
Sampling point 4: S7 Dark Surface. This is an example of where horizons and layers
are not synonymous. To meet this indicator,youmusthave10cm(4in.)withavalue
of 3 or less and a chroma of 1 or less. Immediately below the 10 cm (still in the same
horizon), you meet the next layer requirement with a chroma of 2 or less. However, if
you went to the next horizon instead of looking immediately below the 10 cm layer,
you would not meet this indicator since it has a chroma higher than 2. S7 is not an
approved indicator for all LRRs. When identifying indicators in a real world scenario
you would need to identify that you are in an approved LRR before using this indicator.
Sampling point 5: Answer: A11 Depleted Below Dark Surface. Note that if you
incorrectly start your measurements at the actual soil surface instead of the mineral
surface (at 5 cm), the depleted matrix would be too deep to meet this indicator.
Laboratory Exercises
Laboratory Exercise: Description and Identification
of Hydric Soils in the Field
Overview: The following field exercise is intended to allow you to use the skills you
have learned to make a hydric soils determination in the field. If you are a novice to
writing soil descriptions, you may want to seek out assistance from a soil or wetland
scientist with more experience for assistance. Before you go to the field, you will need
to gather the soil report you created earlier in Web Soil Survey for the area you will
be using for the excercise, a copy of the Field Indicators of Hydric Soils in the United
States (Version 7.0), a copy of Chapter 3 of your local Corps Regional Supplement,
and the Key to Soils that Lack Field Indicators of Hydric Soils.
Objectives: To describe and identify hydric soils in the field
Materials and Equipment Needed:
1. Tiling spade or similar flat bladed shovel
2. Bucket auger if you think you may need to describe your soil to a depth greater
than 45 cm (18 in.).
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