soil is saturated. Soils with peraquic moisture regimes are 

 characterized by the presence of ground water always at or near 

 the soil surface. Examples include soils of tidal marshes and 

 soils of closed, landlocked depressions that are fed by perma- 

 nent streams. 



Reducing soil conditions. Soils saturated for long or very 

 long duration will usually exhibit reducing conditions. Under 

 such conditions, ions of iron are transformed from a ferric 

 valence state to a ferrous valence state. This condition can 

 often be detected in the field by a ferrous iron test. A 

 simple colorimetric field test kit has been developed for this 

 purpose. When a soil extract changes to a pink color upon 

 addition of a-a-dipyridil, ferrous iron is present, which 

 indicates a reducing soil environment. NOTE: This test cannot 

 he used in mineral hydric soils having low iron content, 

 organic soils, and soils that have been desaturated for signif- 

 icant periods of the growing season. 



Soil colors. The colors of various soil components are often 

 the most diagnostic indicator of hydric soils. Colors of these 

 components are strongly influenced by the frequency and dura- 

 tion of soil saturation, which leads to reducing soil condi- 

 tions. Mineral hydric soils will be either gleyed or will have 

 bright mottles and/or low matrix chroma. These are discussed 

 below: 



(1) Gleyed soils (gray colors). Gleyed soils develop when 

 anaerobic soil conditions result in pronounced chemical 

 reduction of iron, manganese, and other elements, thereby 

 producing gray soil colors. Anaerobic conditions that oc- 

 cur in waterlogged soils result in the predominance of re- 

 duction processes, and such soils are greatly reduced. 

 Iron is one of the most abundant elements in soils. Under 

 anaerobic conditions, iron in converted from the oxidized 

 (ferric) state to the reduced (ferrous) state, which re- 

 sults in the bluish, greenish, or grayish colors asso- 

 ciated with the gleying effect (Figure 4). Gleying imme- 

 diately below the A-horizon or 10 inches (whichever is 

 shallower) is an indication of a markedly reduced soil, 

 and gleyed soils are hydric soils. Gleyed soil conditions 

 can be determined by using the gley page of the Munsell 

 Color Book (Munsell Color 1975). 



(2) Soils with bright mottles and/or low matrix chroma. 

 Mineral hydric soils that are saturated for substantial 

 periods of the growing season (but not long enough to 

 produce gleyed soils) will either have bright mottles and 

 a low matrix chroma or will lack mottles but have a low 

 matrix chroma (see Appendix D, Section 1, for a definition 

 and discussion of "chroma" and other components of soil 

 color). Mottled means "marked with spots of contrasting 

 color." Soils that have brightly colored mottles and a 

 low matrix chroma are indicative of a fluctuating water 

 table. The soil matrix is the portion (usually more than 

 50 percent) of a given soil layer that has the predominant 



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