Field Indicators of Hydric Soils in the United States - ITC
Field Indicators of Hydric Soils in the United States - ITC
Field Indicators of Hydric Soils in the United States - ITC
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<strong>Field</strong> <strong>Indicators</strong> <strong>of</strong> <strong>Hydric</strong> <strong>Soils</strong>F4. Depleted Below Dark Surface. For use <strong>in</strong> allLRRs except W, X, and Y; for test<strong>in</strong>g <strong>in</strong> LRRs W, X,and Y. A layer with a depleted matrix that has 60percent or more chroma 2 or less start<strong>in</strong>g with<strong>in</strong>30 cm (12 <strong>in</strong>) <strong>of</strong> <strong>the</strong> soil surface that has a m<strong>in</strong>imumthickness <strong>of</strong> ei<strong>the</strong>r:a. 15 cm (6 <strong>in</strong>),b. 5 cm (2 <strong>in</strong>) if <strong>the</strong> 5 cm (2 <strong>in</strong>) consists <strong>of</strong>fragmental soil material (see glossary).The layer(s) above <strong>the</strong> depleted matrix has value3 or less and chroma 2 or less.Depleted Below Dark Surface User Notes: This<strong>in</strong>dicator <strong>of</strong>ten occurs <strong>in</strong> Mollisols, but also applies tosoils that have umbric epipedons and dark coloredochric epipedons. For soils that have dark coloredepipedons greater than 30 cm (12 <strong>in</strong>) thick, useIndicator F5. Redox concentrations <strong>in</strong>clud<strong>in</strong>g iron/Figure 23. Indicator F3 Depleted Matrix. The chroma is 2below a depth <strong>of</strong> about 15 cm. Redox concentrationsare present. Scale is <strong>in</strong>ches.manganese s<strong>of</strong>t masses, pore l<strong>in</strong><strong>in</strong>gs, or both, arerequired <strong>in</strong> soils that have matrix colors <strong>of</strong> 4/1, 4/2,and 5/2. A, E, and calcic horizons may have lowchromas depleted matrix; however, <strong>the</strong>y are excludedfrom <strong>the</strong> concept <strong>of</strong> depleted matrix unlesscommon or many, dist<strong>in</strong>ct or prom<strong>in</strong>ent redox concentrationsas s<strong>of</strong>t masses or pore l<strong>in</strong><strong>in</strong>gs arepresent. See glossary for <strong>the</strong> def<strong>in</strong>ition <strong>of</strong> depletedmatrix.F5. Thick Dark Surface. For use <strong>in</strong> all LRRs exceptW, X, and, Y; for test<strong>in</strong>g <strong>in</strong> LRRs W, X, and Y. Alayer at least 15 cm (6 <strong>in</strong>) thick with a depletedmatrix that has 60 percent or more chroma 2 orless (or a gleyed matrix) start<strong>in</strong>g below 30 cm(12 <strong>in</strong>) <strong>of</strong> <strong>the</strong> surface. The layer(s) above <strong>the</strong>depleted or gleyed matrix has hue N and value 3or less to a depth <strong>of</strong> 30 cm (12 <strong>in</strong>) and value 3 orless and chroma 1 or less <strong>in</strong> <strong>the</strong> rema<strong>in</strong>der <strong>of</strong> <strong>the</strong>epipedon.Thick Dark Surface User Notes: The soil has ablack or very dark gray surface layer 30 cm (12 <strong>in</strong>)or more thick (figs. 25 and 26). The dark subsoil hasvalue 3 or less, and chroma 1 or less. Below <strong>the</strong> darkcolored epipedon is a depleted matrix or gleyedmatrix. This <strong>in</strong>dicator is most <strong>of</strong>ten associated withoverthickened soils <strong>in</strong> concave landscape positions.Figure 24. Indicator F3 Depleted Matrix. The chroma is 1with<strong>in</strong> a depth <strong>of</strong> about 10 to 15 cm. Redoxconcentrations are absent. Scale is <strong>in</strong>ches.(430, FIHS, Ver. 5.01, March 2003) 15
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