Field Indicators of Hydric Soils in the United States - ITC

Field Indicators of Hydric Soilsconcept of depleted matrix unless common or many,distinct or prominent redox concentrations as softmasses or pore linings are present.Figure 27. Indicator F6 Redox Dark Surface. Prominentredox concentrations as soft masses and porelinings are present. Below the dark epipedon isindicator F4 Depleted Dark Surface. Scale iscm.F7. Depleted Dark Surface. For use in all LRRsexcept W, X, and Y; for testing in LRRs W, X, and Y.Redox depletions, with value 5 or more andchroma 2 or less, in a layer at least 10 cm(4 in) thick entirely within the upper 30 cm(12 in) of the mineral soil that has:a. matrix value 3 or less and chroma 1 orless and 10 percent or more redoxdepletions, orb. matrix value 3 or less and chroma 2 orless and 20 percent or more redoxdepletions.Depleted Dark Surface User Notes: Care should betaken not to mistake mixing of an E or calcic horizoninto the surface layer as depletions. The pieces of Eand calcic horizons are not redox depletions. Knowledgeof local conditions is required in areas where Eand/or calcic horizons may be present. In soils thatare wet because of subsurface saturation, the layerimmediately below the dark surface should have adepleted or gleyed matrix. Redox depletions shouldhave associated microsites with redox concentrationsthat occur as Fe pore linings or masses withinthe depletion(s) or surrounding the depletion(s).Figure 28. Indicator F6 Redox Dark Surface. Often, as inthis soil, the redox concentrations are small(fine).F8. Redox Depressions. For use in all LRRs exceptW, X, and Y; for testing in LRRs W, X, and Y. Inclosed depressions subject to ponding, 5 percentor more distinct or prominent redox concentrationsas soft masses or pore linings in a layer 5cm (2 in) or more thick entirely within theupper 15 cm (6 in) of the soil surface (fig. 29).Redox Depressions User Notes: This indicatoroccurs on depressional landforms, such as vernalpools, playa lakes, rainwater basins, grady ponds,and potholes; but not microdepressions on convex orplane landscapes.F9. Vernal Pools. For use in LRRs C and D. Inclosed depressions subject to ponding, presenceof a depleted matrix in a layer 5 cm (2 in) thickentirely within the upper 15 cm (6 in) of the soilsurface.Vernal Pools User Notes: Most often soils pondwater for two reasons: they occur on landscapepositions that collect water and they have a restrictivelayers(s) that prevents water from movingdownward through the soil. Normally this indicatoroccurs at the soil surface. Redox concentrationsincluding iron/manganese soft masses or pore linings,or both, are required in soils that have matrix(430, FIHS, Ver. 5.01, March 2003) 17