In ABC soil, the second or subsurface zone of soil made of clay and oxidized materials and organic matter obtained from the A-horizon by leaching; subsoil.

• b层，淀积层在分a、b、c层位土壤中的第二层即表层之下的土壤部分，由粘土、氧化物质和从a层位通过过滤得到的有机物组成；下层土