I am looking for guidance on the F6 indicator for loamy/clay soils within the Regional Supplement for Western Mountains, Valleys, and Coast (page 58).
I'm sure this indicator is used in other regions as well.
The description says the layer must be entirely within the upper 12 in.
This seems odd to me since the redox area within the dark surface often extends below 12 inches. In fact, this indicator seems to be the new iteration of a primary indicator in the 87 manual, i.e. dark surface and redox below 10 inches, except the layer thickness descriptions are different. This new description seems to imply that if the layer goes beyond the 12 inch threshold, then the indicator is not applied.
Likewise, indicator F7 also has a 12 inch threshold.
Any guidance on this will be appreciated!

The definition states: A layer that is at least 4 in. (10 cm) thick, is entirely
within the upper 12 in. (30 cm) of the mineral soil, and has a:

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There has to be at least 4in of indicator within the upper 12in of soil. So if you have a soil profile 12in deep and only the lower 3in are indicator the soil would fail the indicator test.

OK, well that would make sense but I don't see how one is supposed to get that from the description when the layer is to be "entirely" within the upper 12 inches.

If the soil pit is 16" deep and the indicators are from 8 to 13" (dark surface with lots of redox), then the layer would not be entirely in the upper 12 inches, even though this scenario would definitely cry wetland to me if the hydrology and veg. were present.
Are you saying this scenario would meet the indicator because 4 inches are within the upper 12" of the soil? How do you explain "entirely' in the current context?

Another scenario:
16" pit, indicators are from 10-14" (dark surface with lots of redox). This is one I see often and that would have met the 87 guidelines, but would not meet the current indicator in question. This is a head-scratcher but is clearly not meeting the current definition.

Any more thoughts from Tommy or others would be much appreciated.

OK, I think you are 'over thinking' this a little. The indicator calls for a 4" zone (layer) to be in the upper 12"...so if it starts at 8 and goes to 13, you have a 4 inch zone that is entirely in the upper 12", and the 12-13" is 'extra'. If your layer starts at 10" and goes to 14", it does not meet the indicator.
The layers in indocators do not always exactly align with horizons, or even layers, we describe in the soil.

I understand how the phrase "is entirely" makes you pause when reading that indicator. It would read better like this:

quote:

A layer that is at least 10 cm (4 in) thick, is entirely within the upper 30 cm (12 in) of the mineral soil, and has:....

Michael, is there a need for that phrase in the description?

This part of the description in the manual should help.
"The layer meeting the requirements of the indicator may extend below 12 in. (30 cm) as long as at least 4 in. (10 cm) occurs within 12 in. (30 cm) of the surface."

Page 59 of the manual.

The wording is confusing.