the soil sample with a Munsell soil color chart. The 

 standardized Munsell soil colors are identified by 

 three components: hue, value, and chroma. The 

 hue is related to one of the main spectral colors: 

 red, yellow, green, blue, or purple, or various mix- 

 tures of these principal colors. The value refers to 

 the degree of lightness, while the chroma notation 

 indicates the color strength or purity. In the Mun- 

 sell soil color book, each individual hue has its 

 own page, each of which is further subdivided into 

 units for value (on the vertical axis) and chroma 

 (horizontal axis). Although theoretically each soil 

 color represents a unique combination of hues, val- 

 ues, and chromas, the number of combinations 

 common in the soil environment usually is limited. 

 Because of this situation and the fact that accurate 

 reproduction of each soil color is expensive, the 

 Munsell soil color book contains a limited number 

 of combinations of hues, values, and chromas. The 

 color of the soil matrix or a mottle is determined by 

 comparing a soil sample with the individual color 

 chips in the soil color book. The appropriate Mun- 

 sell color name can be read from the facing page in 

 the "Munsell Soil Color Charts" (Kollmorgen Cor- 

 poration 1975). Chromas of 2 or less are consid- 

 ered low chromas and are often diagnostic of hy- 

 dric soils. Low chroma colors include black, 

 various shades of gray, and the darker shades of 

 brown and red. 



Hydric Organic Soils 



3.18. Hydric organic soils can be easily recog- 

 nized as black-colored muck and/or as black to dark 

 brown-colored peat. Distinguishing mucks from 

 peats based on the relative degree of decomposition 

 is fairly simple. In mucks (Saprists), almost all of 

 the plant remains have been decomposed beyond 

 recognition. When rubbed, mucks feel greasy and 

 leave hands dirty. In contrast, the plant remains in 

 peats (Fibrists) show very littie decomposition and 

 the original constituent plants can be recognized 

 fairly easily. When the organic material is rubbed 

 between the fingers, most plant fibers will remain 

 identifiable, leaving hands relatively clean. Be- 

 tween the extremes of mucks and peats, organic 

 soils with partially decomposed plant fibers (Hem- 

 ists) can be recognized. In peaty mucks up to two- 

 thirds of the plant fibers can be destroyed by rub- 

 bing the materials between the fingers, while in 

 mucky peats up to two-thirds of the plant remains 

 are still recognizable after rubbing. 



3.19. Besides the dominance of organic matter, 

 many organic soils (especially in tidal marshes) also 

 emit an odor of rotten eggs when hydrogen sulfide 

 is present. Sulfides are produced only in a strongly 

 reducing environment. 



Hydric Mineral Soils 



3.20. Hydric mineral soils are often more difficult 

 to identify than hydric organic soils because most 

 organic soils are hydric, while most mineral soils 

 are not. A thick dark surface layer, grayish subsur- 

 face and subsoil colors, the presence of orange or 

 reddish brown (iron) and/or dark reddish brown or 

 black (manganese) motties or concretions near the 

 surface, and the wet condition of the soil may help 

 identify the hydric character of many mineral soils. 

 The grayish subsurface and subsoil colors and 

 thick, dark surface layers are the best indicators of 

 current wetness, since the orange-colored mottles 

 are very insoluble and once formed may remain in- 

 definitely as relict mottles of former wetness (Diers 

 and Anderson 1984). 



National and State Hydric Soils Lists 



3.21. The SCS in cooperation with the National 

 Technical Committee for Hydric Soils (NTCHS) 

 has prepared a list of the Nation's hydric soils. 

 State lists have also been prepared for statewide 

 use. The national and State lists identify those soil 

 series that meet the hydric soil criteria according to 

 available soil interpretation records in SCS's soils 

 database. These lists are periodically updated, so 

 make sure the list being used is the current list. The 

 lists facilitate use of SCS county soil surveys for 

 identifying potential wetiands. One must be careful, 

 however, in using the soil survey, because a soil 

 map unit of an upland (nonwetiand) soil may have 

 inclusions of hydric soil that were not delineated on 

 the map or vice versa. Also, some map units (e.g., 

 alluvial land, swamp, tidal marsh, muck and peat) 

 may be hydric soil areas, but are not on the hydric 

 soils lists because they were not given a series 

 name at the time of mapping. 



3.22. Because of these limitations of the national 

 and State lists, the SCS also maintains lists of hy- 

 dric soil map units for each county in the United 

 States. These lists may be obtained from local SCS 

 district offices and are the preferred lists to be used 

 when locating areas of hydric soils. The hydric soil 



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