For use in LRRs P (except for MLRA 136), T, U, and Z.

A layer of mucky modified mineral soil material 5 cm (2 inches) or more thick, starting at a depth ≤15 cm (6 inches) from the soil surface.

User Notes: “Mucky” is a USDA texture modifier for mineral soils. The content of organic carbon is at least 5 percent and ranges to as high as 18 percent. The percentage required depends on the clay content of the soil; the higher the clay content, the higher the content of organic carbon required. For example, a mucky fine sandy soil contains between 5 and 12 percent organic carbon. When the amount of clay is increased as in a mucky sandy loam, the organic carbon content increases to between 7 and 14 percent.