For use in all LRRs, except for Q, V, W, X, and Y.
A layer starting at a depth of 15 cm (6 inches) or less from the soil surface that is 10 cm (4 inches) or more thick and has a matrix with 60 percent or more chroma of 2 or less and 2 or more percent distinct or prominent redox concentrations occurring as soft masses and/or pore linings.
User Notes: “Distinct” and “prominent” are defined in the “Glossary.” Redox concentrations include iron and manganese masses (reddish mottles) and pore linings (Vepraskas, 1994). Included within the concept of redox concentrations are iron-manganese bodies occurring as soft masses with diffuse boundaries. Common (2 to less than 20 percent) or many (20 percent or more) redox concentrations are required. If the soil is saturated at the time of sampling, it may be necessary to let it dry to a moist condition for redox features to become visible (figs. 23 and 24). This is a very common indicator of hydric soils and is often used to identify the hydric and nonhydric soil boundary in sandy soil layers.