known as peats and mucks. All other hydrlc soils are mineral soils. Mineral 

 soils have a wide range of textures (sandy to clayey) and colors (red to 

 gray) . Mineral hydric soils are those periodically saturated for sufficient 

 duration to produce chemical and physical soil properties associated with a 

 reducing environment. They are usually gray and/or mottled immediately below 

 the surface horizon (see paragraph 44d) , or they have thick, dark-colored 

 surface layers overlying gray or mottled subsurface horizons. 

 Wetland indicators (nonsandy soils) 



44. Several indicators are available for determining whether a given 

 soil meets the definition and criteria for hydric soils. Any one of the 

 following indicates that hydric soils are present:* 



a. Organic soils (Histosols) . A soil is an organic soil when: 

 (1) more than 50 percent (by volume) of the upper 32 inches of 

 soil is composed of organic soil material;** or (2) organic 

 soil material of any thickness rests on bedrock. Organic soils 

 (Figure 3) are saturated for long periods and are commonly 

 called peats or mucks. 



b. Histic epipedons. A histic epipedon is an 8- to 16-inch layer 

 at or near the surface of a mineral hydric soil that is satu- 

 rated with water for 30 consecutive days or more in most years 

 and contains a minimum of 20 percent organic matter when no 

 clay is present or a minimum of 30 percent organic matter when 

 clay content is 60 percent or greater. Soils with histic 

 epipedons are inundated or saturated for sufficient periods to 

 greatly retard aerobic decomposition of the organic surface, 

 and are considered to be hydric soils. 



c. Sulfidic material. When mineral soils emit an odor of rotten 

 eggs, hydrogen sulfide is present. Such odors are only 

 detected in waterlogged soils that are permanently saturated 

 and have sulfidic material within a few centimetres of the soil 

 surface. Sulfides are produced only in a reducing environment. 



d. Aquic or peraquic moisture regime. An aquic moisture regime is 

 a reducing one; i.e., it is virtually free of dissolved oxygen 

 because the soil is saturated by ground water or by water of 

 the capillary fringe (USDA-SCS 1975). Because dissolved oxygen 

 is removed from ground water by respiration of microorganisms, 

 roots, and soil fauna, it is also implicit that the soil tem- 

 perature is above biologic zero (5° C) at some time while the 



* Indicators are listed in order of decreasing reliability. Although all 



are valid indicators, some are stronger indicators than others. When a 



decision is based on an indicator appearing in the lower portion of the 



list, re-evaluate the parameter to ensure that the proper decision was 

 reached. 



** A detailed definition of organic soil material is available in USDA-SCS 

 (1975). 



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