Explain the processes of pedogenesis, and identify the active and passive factors affecting it.

Pedogenesis is the process of soil formation which may take hundreds of years. Soil cover is vital for agriculture and life itself.

Process of soil formation:

• The base material is the rock which may be found in-situ or deposited by wind and water.
• The rocks are broken down by agents of weathering like heat, wind, water and ice.
• Eventually the size of rock is reduced to the extent of fine particles, which are termed as sand/silt/clay.
• Therefore, soil formation occurs over a long time period with formation of distinct layers with the uppermost layer containing the smallest size of particles whereas the lowermost layer contains the bedrock.

The active factors influencing soil formation are:

• Climate – warm and wet climate speeds up weathering and soil formation, e.g. dissolution of rocks.
• Microbes – earthworms by burrowing and bacteria and fungi through biological processes help form soil.
• Human activity – blasting of mountains, construction activities contribute to faster soil formation.

The passive factors influencing soil formation are:

• Parent material – Type of parent material can dictate soil type, e.g. the basalt rock leads to formation of black soil, ferrous rocks lead to formation of red soil.
• Relief – Topography influences the extent of soil formation, e.g. soil cover is thin along hill slopes and comparatively thick along plains.
• Time – Sufficient time is needed for formation of mature soil.

The soil cover sustains the economy and ensures food and nutritional security. Thus, it is of utmost importance to reverse the phenomena of soil erosion and desertification which destroys the soil cover.

Topics: GS-I: Important Geophysical Phenomena