Swamp Stomp
Volume 14, Issue 22
The National Technical Committee for Hydric Soils (NTCHS) meets annual to discuss changes to its understanding of hydric soils and their indicators. This committee is a mix of Corps, NRCS, BLM, EPA, FWS and an number of University representatives. During their last meeting in Alabama there was a motion to replace one of the hydric soil indicators with a new one.
Before we go into this it is important to note that the NTCHS does not speak for the US Army Corps of Engineers and the regional supplements. As many of you know much of the new Corps hydic soil indicators are taken from the NTCHS Field Indicators Manual. However, any change the NTCHS makes only applies to the NTCHS manual and not the Corps’ regional supplements. However, there is a provision with each regional supplement to suggest that the NTCHS manual can be used in certain circumstances in addition to the regional interpretations. So it is important to keep up with these changes.
TF12. Very Shallow Dark Surface. For testing in all LRRs. In depressions and other concave landforms.
This indicator has come under scrutiny in the marl regions of Florida. The NTCHS has replaced it with a new F22-Very Shallow Dark Surface Indicator.
It is described as follows:
Replace:
TF12. Very Shallow Dark Surface. For testing in all LRRs. In depressions and other concave landforms, one of the following:
if bedrock occurs between 15 cm (6 inches) and 25 cm (10 inches), a layer at least 15 cm (6 inches) thick starting within 10 cm (4 inches) of the soil surface with value 3 or less and chroma 1 or less, and the remaining soil to bedrock must have the same colors as above or any other color that has a chroma 2 or less.
if bedrock occurs within 15 cm (6 inches), more than half of the soil thickness must value 3 or less and chroma 1 or less, and the remaining soil to bedrock must have the same colors as above or any other color that has a chroma 2 or less.
With:
F22. Very Shallow Dark Surface. For use in MLRA 138 of LRR P, MLRA 154 of LRR U, and West Florida portion of MLRA 152A, LRR P. For testing in all other MLRAs and LRRs. In depressions and flood plains subject to frequent ponding and/or flooding, one of the following:
if bedrock occurs between 15 cm (6 inches) and 25 cm (10 inches), a layer at least 15 cm (6 inches) thick starting within 10 cm (4 inches) of the soil surface with value 2.5 or less and chroma 1 or less, and the remaining soil to bedrock must have the same colors as above or any other color that has a chroma 2 or less.
if bedrock occurs within 15 cm (6 inches), more than half of the soil thickness must have value 2.5 or less and chroma 1 or less, and the remaining soil to bedrock must have the same colors as above or any other color that has a chroma 2 or less.
The short version of this is that it is indicator F6 adapted to very shallow soils over bedrock.
If you are working in Florida this is a new soil tool for your toolbox.
Have a great week!
Marc