Question

Humus is formed in
A)Horizon-A
B)Horizon-O
C)Horizon-B
D)Both A and B

Answer 1

Soil is a layer of material that makes up the upper surface of the earth. They comprise organic matter, water , air, rocks as well as living organisms.

Complete answer:
Soil is arranged in different layers or horizons during its formation which makes up the soil profile. The major layers of soil are- topsoil, subsoil and parent rock, each of which can be distinguished by their colour and size of soil particles. The different horizons of the soil are represented by different letters- O, A, E , C , B and R. the O horizon makes the uppermost layer and is black brown or dark brown due to the presence of organic constituents that make humus which increases the fertility of the soil.

The A horizon also comprises humus, it is in this region where seed germination and new roots are produced. The E horizon comprises nutrients that has been leached from the A and O horizons. The B horizon is located below the topsoil and is light brown in colour due to the presence of clay soil. The C horizon comprises broken bedrock and no organic constituent. The R horizon is a cemented layer that contains different rocks such as granite, limestone and basalt.

Hence, the correct answer is option (D)

Note: The soil profile plays an important role in determining the role of the particular type of soil. It helps in fertility maintenance as well as nutrient content maintenance of the soil.