All soil contains some humus. If it doesn't it is not soil.
The C and R horizon
Topsoil contains organic matter (humus)
the two layers are sub soil The layer of soil that has little or no humus in it is the subsoil. The top layer of the soil has the most humus in it because the dead leaves fall from the plant and go back into the soil.
Humus
bed rock
Humus is located in the top layer of soil. It is a type of organic soil matter and aids in nutrition retention in the soil.
the O-Horizon is the topmost soil so it has the most humus
topsoil
topsoil
HUMUS . . . cures urvythang.
Humus