si·er·o·zem 
(sī-ĕrə-zĕm′, sē-ĕr′ə-zhôm)
(sī-ĕrə-zĕm′, sē-ĕr′ə-zhôm)n.
Any of a group of soils found in cool to temperate arid regions that is brownish gray at the surface with a lighter layer below and is based in a carbonate or hardpan layer.
[Russian serozem : seryĭ, gray + Old Russian zemĭ, earth; see dhghem- in the Appendix of Indo-European roots.]