Q. Which of the following Horizon of soil, primarily where organic materials have got incorporated with the mineral matter, nutrients and water, which are necessary for the growth of plants?

[A] Horizon A

[B] Horizon B

[C] Horizon C

[D] Horizon A & C

Answer: A
Notes:

Explanation: If we dig a pit on land and look at the soil, we find that it consists of three layers which are called horizons.

  • ‘Horizon A’ is the topmost zone, where organic materials have been incorporated with mineral matter, nutrients and water, which are necessary for the growth of plants.
  • ‘Horizon B’ is a transition zone between ‘horizon A’ and ‘horizon C’, and contains matter derived from below as well as from above.
  • It has some organic matter in it, although the mineral matter is noticeably weathered.
  • ‘Horizon C’ is composed of loose parent material. This layer is the first stage in the soil formation process and eventually forms the above two layers.

This arrangement of layers is known as the soil profile.

Source: NCERT – Fundamental of Physical Geography