Is there a thick layer of humus in Cold deserts.

No, cold deserts typically have a very thin layer of humus or organic matter. Cold deserts have harsh environments with extremely cold temperatures, low precipitation, and sparse vegetation. The cold temperatures and lack of moisture limit the decomposition of organic matter, resulting in a slow accumulation of humus. Additionally, the limited vegetation in cold deserts means there is less organic material available to contribute to the formation of humus.