(a) Soil is the most important renewable natural resource. It is the medium of plant growth and supports different types of living organisms on the earth.
(b) The soil is a living system. It takes millions of years to form soil up to a few centimetre in depth. Important factors responsible for the soil formation are as follows:
(l) Rocks: Parent rock or bed rock on which the soils are formed, disintegrate and decompose under the process of weathering and erosion.
(ii) Climate: It determines the rate of weathering and the type of vegetation.
(iii) Slope: It decides the accumulation of soils.
(iv) Various forces of nature such as change in temperature, actions of running water, wind and glaciers, activities of decomposers etc. contribute to the formation of soil.
(v) Chemical and organic changes to play their role in the formation of soil.