Question

.....horizon is a rich humus ​

Answer 1

Answer:

topsoil

The uppermost layer is called topsoil and this layer contains humus, plant roots, and living creatures. The more humus found in topsoil, the more nutrient rich the topsoil and the better the conditions for growing plants. The middle layer is called subsoil.

Answer 2

Answer:

Topsoil horizon is a rich humus.