Figure 16.—Indicator A11, Depleted Below Dark Surface.
This photo accompanies Figure 16.—Indicator A11 (Depleted Below Dark Surface). [Field Indicators of Hydric Soils in the United States].
Typical landscape, soil profile, and redox features of the Hegne soil. The Hegne series (Typic Calciaquerts) consists of very deep, poorly drained soils that formed in clayey calcareous lacustrine sediments on glacial lake plains. These soils have slow or very slow permeability. They have slopes of 0 to 2 percent. Mean annual precipitation is about 20 inches. Mean annual air temperature is about 42 degrees F.
The Hegne soils have slightly convex to slightly concave slopes of less than 2 percent on glacial lake plains and in a few places these soils are on flood plains. These soils commonly are on the higher lying positions of microrelief topography. They formed in clayey lacustrine sediments of Late Wisconsin age. Mean annual air temperature ranges from 38 to 45 degrees F. Mean annual precipitation ranges from 15 to 27 inches. Frost-free days range from 90 to 140. Elevation above sea level ranges from 650 to 1800 feet.
Nearly all of these soils are cultivated. Principal crops are small grains and sugar beets. Native vegetation is tall grass prairie. Hegne soils are of large extent principally in the Red River Valley of northwestern Minnesota and eastern North Dakota, also in smaller glacial lake basins in western Minnesota and north-central North Dakota.
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A, E, and calcic horizons may have low chromas and high values and may therefore be mistaken for a depleted matrix. They are excluded from the concept of depleted matrix unless the soil has common or many distinct or prominent redox concentrations occurring as soft masses or pore linings.
Soil profile and features:
This indicator often occurs in Mollisols (mollic epipedon) but also applies to soils with umbric epipedons and dark colored ochric epipedons. For soils with dark colored epipedons more than 30 cm (12 inches) thick, use indicator A12.
Note: A depleted matrix requires value of 4 or more and chroma of 2 or less. Redox concentrations, including soft iron-manganese masses and/or pore linings, are required in soils with matrix colors of 4/1, 4/2, or 5/2.
This soil has a depleted matrix directly under the surface horizon: (10YR 4/2) in the upper part (Bkssg1) and (10YR 5/2) in the lower part (Bkssg2) with common to many distinct or prominent redox concentrations (soft masses of iron accumulation) and redox depletions (iron depletions), increasing with depth.
Figure 16.—Indicator A11, Depleted Below Dark Surface.
This photo accompanies Figure 16.—Indicator A11 (Depleted Below Dark Surface). [Field Indicators of Hydric Soils in the United States].
Typical landscape, soil profile, and redox features of the Hegne soil. The Hegne series (Typic Calciaquerts) consists of very deep, poorly drained soils that formed in clayey calcareous lacustrine sediments on glacial lake plains. These soils have slow or very slow permeability. They have slopes of 0 to 2 percent. Mean annual precipitation is about 20 inches. Mean annual air temperature is about 42 degrees F.
The Hegne soils have slightly convex to slightly concave slopes of less than 2 percent on glacial lake plains and in a few places these soils are on flood plains. These soils commonly are on the higher lying positions of microrelief topography. They formed in clayey lacustrine sediments of Late Wisconsin age. Mean annual air temperature ranges from 38 to 45 degrees F. Mean annual precipitation ranges from 15 to 27 inches. Frost-free days range from 90 to 140. Elevation above sea level ranges from 650 to 1800 feet.
Nearly all of these soils are cultivated. Principal crops are small grains and sugar beets. Native vegetation is tall grass prairie. Hegne soils are of large extent principally in the Red River Valley of northwestern Minnesota and eastern North Dakota, also in smaller glacial lake basins in western Minnesota and north-central North Dakota.
______________________________
A, E, and calcic horizons may have low chromas and high values and may therefore be mistaken for a depleted matrix. They are excluded from the concept of depleted matrix unless the soil has common or many distinct or prominent redox concentrations occurring as soft masses or pore linings.
Soil profile and features:
This indicator often occurs in Mollisols (mollic epipedon) but also applies to soils with umbric epipedons and dark colored ochric epipedons. For soils with dark colored epipedons more than 30 cm (12 inches) thick, use indicator A12.
Note: A depleted matrix requires value of 4 or more and chroma of 2 or less. Redox concentrations, including soft iron-manganese masses and/or pore linings, are required in soils with matrix colors of 4/1, 4/2, or 5/2.
This soil has a depleted matrix directly under the surface horizon: (10YR 4/2) in the upper part (Bkssg1) and (10YR 5/2) in the lower part (Bkssg2) with common to many distinct or prominent redox concentrations (soft masses of iron accumulation) and redox depletions (iron depletions), increasing with depth.