cher·no·zem 
(chĕrnə-zĕm′, chîr′nə-zyôm)
(chĕrnə-zĕm′, chîr′nə-zyôm)n.
A very black topsoil, rich in humus, typical of cool to temperate semiarid regions such as the grasslands of Ukraine and southern Russia.
[Russian chernozëm : chërnyĭ, black + Old Russian zemĭ, earth; see dhghem- in the Appendix of Indo-European roots.]
cher′no·zemic adj.