Question

Define pedology and pedogenesis. Explain different steps of pedogenesis.

Answer 1

Hint: Pedology and edaphology are two main branches of soil science. The formation of soil requires hundreds of years to occur.

Complete answer:
Pedology is the study of soil classification, soil morphology, and pedogenesis, that is, the study of the processes leading to soil formation. Soils develop from the parent material by various processes of weathering. Organic matter accumulation, decomposition, and humification are as critically important for soil formation by weathering.
Pedogenesis or soil formation is a very prolonged process involving an array of steps. They are:
-Weathering of rocks: It refers to the breakdown of rocks into fine pieces to form soil particles. It can be due to physical, chemical, or biological causes.
a) Physical weathering- It results due to the continuous action of heating and cooling, drying and wetting, rain, wind, frost, and snow.
b) Chemical weathering- It results due to chemical reactions such as carbonization, oxidation, reduction, and solubilization.
c) Biological weathering- It is a result of the catabolic action of fungus, mosses, lichens, etc. on the rocks.
-Humification- It refers to the deposition of a layer of organic matter or humus over the soil surface. It is mainly responsible for the enrichment of the soil, aeration, regulation of biogeochemical cycles, prevention of soil compaction, and increasing the water holding capacity of the soil.
-Eluviation- Here the soil particles which are held in suspension, such as clay, are removed, that is, washed away.
-Illuviation- Here the soil particles which are held in suspension, such as clay, are accumulated, that is, deposited.

Note: Soil formation is influenced by mainly five classic factors, they are- parent material, climate, topography, organisms, and time. Soils are generally more developed in areas with higher rainfall and more warmth. The rate of chemical weathering increases by 2-3 fold times when the temperature increases by 10 degrees Celsius.