Answer:
lack of dense vegetation
Step-by-step explanation:
Humus is the product resulting from the decomposed organic matter, from the digestive process of earthworms, forming a natural compost, adding to the soil the remains of animals and dead plants and also their by-products. This organic matter is a result of the fall of plant material in the soil, for this reason, areas with dense vegetation have soil rich in humus, however areas such as hillsides that do not have dense vegetation are poor in humus.