GUIDELINES FOR SOIL DRAINAGE CLASS DETERMINATION IN NEW ENGLAND

Used for Section 404 of Clean Water Act Jurisdictional Interpretations by U.S. Army Corp. of Engineers, New England Division OPERATIONAL DRAFT (Version 27Feb91)

NOTE: These draft guidelines for soil drainage classes were developed (early 1990's) to provide soil morphology features to help determine the drainage class for use with the 1987 Wetland Delineation Manual in the New England Region. This document attempts to capture the central concepts of the drainage classes from the broad network of soil scientists throughout New England.  This document is still in draft form and will most-likely remain as a draft - the Field Indicators for Identifying Hydric Soils in New England  has since replaced the drainage class document.

A. VERY POORLY DRAINED SOILS are soils that have an aquic moisture regime and one of the following:

  1. Organic soil materials that extend from the soil surface to a depth of 16 or more inches (i.e. Histosols).
  2. Organic soil materials that extend from the soil surface to a depth of 8 to 16 inches (i.e. histic epipedon).
  3. A mineral histic epipedon (e.g. organic surface layers that are 4 to 8 inches thick and/or have an organic-rich A or Ap horizon) and, in the soil horizon that lies directly under an O, A, or Ap horizon there are few to common mottles with the matrix chroma of 2 or less or, if there are no mottles in this underlying layer, the matrix chroma is 1 or less.
  4. Sulfidic materials within 20 inches of the soil surface.

 

B. POORLY DRAINED SOILS are soils that have an aquic moisture regime and of the following:

  1. A spodic horizon and a texture that is finer than loamy fine sand in some or all sub-horizons within 20 inches of the soil surface; and have all the following characteristics, with one of these characteristics evident within 10 inches of the soil surface:

a. Mottles within the albic horizon.

b. Organic-rich spodic (Bh) horizon greater than 4 inches thick with matrix colors of value and chrome of 3 or less.

c. Mottles that are common to many, distinct or prominent, are within the upper part of the spodic horizon or are directly below the organic-rich (Bh) horizon.

  1. A spodic horizon and a texture that is loamy fine sand or coarser in all sub-horizons within 20 inches of the soil surface; and have all the following characteristics, with one these characteristics evident within 10 inches of the soil surface:

a. Mottles within the albic horizon.

b. Organic-rich spodic (Bh) horizon greater than 2 inches thick with matrix colors of value and chrome of 3 or less.

c. Mottles that are common to many, distinct or prominent, are within the upper part of the spodic horizon or are directly below the organic-rich (Bh) horizon.

  1. Do not have a spodic horizon and have one of the following:

a. Any soil texture, and the matrix of the soil horizon which is within 20 inches of the surface and directly underlying an O, A, or Ap horizon, is chroma 2 or less when mottles are few to common; or if there are no mottles in this horizon, the matrix chroma is 1 or less.

b. Within 20 inches of the soil surface, both the texture is finer than loamy fine sand in some or all sub-horizons, and there is a subsurface horizon with a matrix color of chroma 2 or less, and one of the following:

(1) In the soil horizon directly underlying an A or Ap horizon and within 10 inches of the soil surface, there are mottles that are common to many, distinct or prominent, and that are chroma 2 or less.
(2) In the soil horizon directly underlying a thick, dark A or Ap horizon, there are mottles that are distinct or prominent, greater than 10% in abundance and that are chroma 2 or less.

c. Within 20 inches of the soil surface, the texture is loamy fine sand or coarser in all sub-horizons, and there is a subsurface horizon with a matrix color of chroma of 3 or less, and one of the following:

(1) In the soil horizon directly underlying a dark A or Ap horizon and within 10 inches of the soil surface, there are mottles that are common to many, distinct or prominent, and that are chrome 3 or less.
(2) In the soil horizon directly underlying a thick, dark A or Ap horizon, there are mottles that are distinct or prominent, greater than l0% in abundance, and that are chroma 3 or less.

 

C. SOMEWHAT POORLY DRAINED SOILS are soils that have an aquic or udic moisture regime and either of the following:

  1. A spodic horizon that is mottled within 16 inches of the soil surface, regardless of the chroma of those mottles.
  2. No spodic horizon and, within 16 inches of the soil surface, there is one of the following:

a. Mottles that are common to many, distinct or prominent, and have a chroma of 3 or less.

b. A matrix chroma of 3 or less with mottles which are common to many, distinct or prominent, regardless of their chroma.

 

D. MODERATELY WELL DRAINED SOILS are soils that have a udic moisture regime and, between a depth of 16 to 40 inches below the soil surface, have one of the following:

  1. Mottles that are common to many, distinct or prominent, and that are chroma 3 or less.
  2. A matrix chroma of 3 or less and mottles that are com to many, distinct or prominent, regardless of their chroma.

E. WELL DRAINED SOILS are soils that have a udic moisture regime and textures finer than loamy fine sand that extend below 20 inches, and are not mottled with 40 inches of the soil surface.

F. SOMEWHAT EXCESSIVELY TO EXCESSIVELY DRAINED SOILS are all other soils.

Endnotes:

a. SOIL SURFACE - For Organic Soils (Histosols) or mineral soils with a thick organic surface layer (histic epipedon), the soil surface is the top of the uppermost organic horizon that is, or has been saturated for prolonged periods. Otherwise, the soil surface is the top of the mineral soil. This definition is intended to be used throughout these guidelines.

b. SOIL COLORS - All soil colors are documented under moist conditions using a Munsell system standardized soil color book. The terms “value” and “chroma” are soil color descriptors used in these guidelines. The term matrix refers to the dominant color that occupies the greatest volume of the horizon or layer.

c. SULFIDIC MATERIALS - in a sample from within a 20 inch depth, hydrogen sulfide gas is present if a strong to very strong odor of rotten eggs is immediately detected. This procedure is accomplished in the field, generally when you open up your pit to describe the soil profile.

d. It is our intent to require this criterion only when an albic horizon is evident. When the horizon is evident, mottling should appear within 10 inches of the soil surface. Obliteration of the albic horizon may occur in areas of poorly drained Spodosols where repeated tree throws mix and often disguise any evidence of a discrete albic (E) horizon above the spodic horizon. Plowing may produce a similar result. Mottling of the albic horizon may be difficult to interpret and may involve faintly contrasting shades of gray.

e. Mottles may be of any chroma.

f. To be thick and dark, this horizon must have a thickness greater than 10 inches and the matrix color must be a value 3 or less and chroma 2 or less.

g. To be dark, this horizon must have a matrix color that is value 3 or less and chroma 2 or less.

h. Faint mottling is allowed within 40 inches of the soil surface for some well drained soils when the soil mottling is associated with contrasting textures or directly overlying a restrictive layer, such as in a compact glacial till.

i. Not all wet soils have been excluded by the morphological criteria used in these guidelines for moderately well drained or better. Some soils within the New England region have developed within mineral parent materials that mask or inhibit the development of soil morphology. These difficult interpretations may include soils developed in Triassic red sandstones, carboniferous schists, strongly calcareous sediments, recently deposited sediments, and an soils adjacent to brackish and salt water bodies, etc. In this region we recognize the need to identify the general locations of these unique soils and the need to develop reliable field criteria for these exceptions.