Question

What is soil? What are the factors of soil formation? Explain with diagram.

Answer 1

• Soil is a resource that is regularly formed by the weathering (breakdown of rocks) forces acting on the surface of earth and its finest form can be found on the surface of the earth.

• Soil formation depends on the parent rock material, the climate and topography of the area, the organisms present in the soil and the time over which the soil has been developing. Over long periods of time, thousands and millions of years, the rocks near the surface of the earth are broken down by various physical, chemical and some biological processes. The end product of this breaking down is the fine particles of soil.

  Physical Process:

  • The Sun:The sun heats up rocks during the day so that they expand. At night, the rocks cool down and contract. This unequal expansion and contraction break up rocks into smaller pieces.
  • Water:Water can get into the cracks formed in the rock due to uneven heating by the sun. If the water freezes, it will widen the rocks. Also fast flowing water carries big and small particles of roc downstream, causing breakdown of rock in to smaller particles.
  • Wind:Strong winds erode rocks down.

  Chemical Process:

  • Lichens grow on surface of rocks release chemical substances which cause the rock surface to powder down and form thin layer of soil.

  Biological Process:

  • Living organisms: Some small plants grown in the cracks of rocks and the roots of big trees break the rocks.