Question

Define pedology and pedogenesis? Explain different steps of pedogenesis

Answer 1

Answer:

Pedology : Study of soils in their natural environment

Pedogenesis :  Process of soil formation

Steps of pedogenesis includes :

1. Weathering  : It is the breaking of rocks into fine particles as present on   the soil. Weathering occurs due to the  following methods :

• Physical Weathering : It is caused by alternate heating and cooling, alternate wetting and drying,  action of frost, snow, rain and wind.

• Chemical Weathering : It involves oxidation, reduction, carbonation and solubilization reactions to  break the rock.

• Biological Weathering : It occurs due to activity of Lichens, Mosses etc.

2. Humification  : It is addition of organic matter or humus into weathered rock. Humification is essential for starting  biological activity and nutritional cycling. Humus is dark coloured amorphous substance, is slightly acidic,  colloidal and acts as reservoir of nutrients.

Main functions of humus are biogeochemical cycling, preventing soil from compaction, helping in  formation of soil crumbs, improving aeration and water holding capacity of soil. It also makes soil spongy,  therefore, easy for penetration by the roots.

3. Eluviation and Illuviation  : These two processes bring about transport and deposition of materials in the soil. Eluviation is washing  down of materials from upper strata. Eluviation helps in enriching the different layers of soil with minerals.  Illuviation is deposition of washed down minerals in lower strata.

Various characteristics of the soil such as soil composition, grain size (particle size) and aggregation  determine the percolation and water holding capacity of the soil. These characteristics along with  parameters such as pH, mineral composition and topography determine to a large extent the vegetation  in any area. This, in turn, dictates the type of animals that can be supported. Similarly, in the aquatic  environment (pond, lake, sea, ocean), the sediment-characteristics often determine the type of benthic  animals that thrive there.