Where would you most likely find humus?

In compost or in soil is where humus tends to be found.

The Word refers to dark brown, fresh-smelling, nutrient-rich organic matter. It may be produced naturally, over time, through erosion. Or it may be produced by human means through the composting of compostable materials in a compost pile, heap or container. Or it may be produced by earthworms breaking down decomposable parts in vermi-composting.