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Hydric Soils Technical Note 7

Changes to "Field Indicators of Hydric Soils in the United States" (Version 4.0, March 1998).

Send comments to Wade Hurt.

The NTCHS met in St. Louis, Missouri in January 1999 and made the following changes and corrections.

Change 1: On page 1 last sentence in column 1 (ending in column 2) is changed to "Saturation or inundation when combined with microbial activity in the soil causes a depletion of oxygen."

Change 2: On page 2 in the first column the third sentence is changed to "Typically, contemporary and recent hydric soil morphologies have diffuse boundaries; relict hydric soil features have sharp boundaries."

Change 3: On page 13 Plate 17 is upside down.

Change 4: On page 15 last sentence in column 1 (ending in column 2) is changed to "A, E and calcic horizons may have low chromas and high values and may therefore be mistaken for a depleted matrix; however, they are excluded from the concept of depleted matrix unless common or many, distinct or prominent redox concentrations as soft masses or pore linings are present."

Change 5: On page 18 in the first column the third sentence in the Iron/Manganese User Note is changed to "Iron/manganese masses should not be confused with the larger and redder iron nodules (US Department of Agriculture, Soil Survey Staff, 1993) associated with plinthitic soils or with concretions that have sharp boundaries."

Change 6: On page 19 in the first column indicator F16 should read as follows:

F16. High Plains Depressions. For use in MLRAs 72 and 73 of LRR H; for testing in other MLRAs of LRR H. In closed depressions subject to ponding, a mineral soil that has chroma 1 or less to a depth of at least 35 cm (11.5 in.) and has a layer at least 10 cm (4 in.) thick within the upper 35 cm (13.5 in.) that has:

a. 1% or more redox concentrations as nodules or concretions, or

b. redox concentrations as nodules or concretions with distinct or prominent corona,

Change 7: On page 23 in the first column the term "Abrupt Boundary" and its definition are deleted.

Change 8: On page 24 in the first column the term "*Diffuse Boundary" is redefined as follows:

*Diffuse Boundary - Used to describe redoximorphic features that grade gradually from one color to another. The color grade is commonly more than 2 mm wide. Clear is used to describe boundary color gradations intermediate between sharp and diffuse. See Plate 31.

Change 9: On page 27 in the first column between the terms "SCS" and "Soft Masses" the following term and definition are added:

Sharp Boundary - Used to describe redoximorphic features that grade sharply from one color to another. The color grade is commonly less than 0.1 mm wide and change is abrupt under a 10X hand lens.

Change 10: On page 30 in the second column between US Department of Agriculture, Natural Resources Conservation Service. 1996b and Vepraskas, M.J. 1994 add the following reference:

U.S. Department of Agriculture, Natural Resources Conservation Service. 1998. Field book for describing and sampling soils. Compiled by P.J. Schoeneberger, D.A. Wysocki, E.C. Benham, and W.D. Broderson. National Soil Survey Center, Lincoln, NE.