Major soil types of India- Characteristics and Classification
Table of Contents
In this article, I will discuss the soil types of India. We all know that soil is the most important layer of the earth. Soil is the uppermost weathered layer of the earth’s crust. The study of soil is known as Pedology. On the other hand, Pedogenesis refers to the formation of soils due to various factors. These factors are relief, parent material, climate, vegetation and other factors. Moreover, the anthropogenic factors (human activities) also involved in the formation of soil. It is a dynamic entity which always undergoes physical, chemical and biological changes.
The composition of soil
The soil is composed of both organic and inorganic material. For example, the weathering of rocks is an inorganic component of soil which provides the volume and weight to the soil. On the other hand, decayed plants and animals, roots of plants, fungi, bacteria, insects etc. constitute the organic component of the soil.
The liquid portion of soil is known as soil solution which is a complex solution necessary for the development of plants. The open spaces (pores) in the soil contains the gases existing in the atmosphere. Thus, the soil is made up of the substances existing in all three states. However, the amount of each component of soil varies according to the type of soil.
Soil profile or soil horizon
The vertical cross-section of the soil is called soil horizons. Soil horizons are the different horizontal layers present in the soil profile. These horizons have their own physical and chemical composition. The following are the different types of horizons of soil.
Organic horizon (O horizon)
It is formed of accumulation of organic matters which are derived from the plants and animals. It also contains surface litters, fallen leaves and partially decomposed organic matter.
Topsoil (A horizon)
It is the uppermost mineral horizon of the soil profile. It is rich in both the humus and inorganic minerals. A horizon is also known as the topsoil of the soil profile.
It mainly constitutes grains of sand or coarse silt which are left behind due to seeping of water.
Subsoil (B horizon)
It is rich in clay, oxides of aluminium and iron. Subsoil receives the aforesaid minerals from the A and E horizons.
Parent material (C horizon)
It consists of weathered parent minerals matter of the soil. C horizon is also known as Saprolite.
Bedrock (R horizon)
R horizon composed of the cemented rocks of granite, basalt and limestone.
Factors controlling the soil formation
Parent material mainly supplies the bases and nutrients to the soil. The parent material determines the colour, mineral composition and texture of the soil. For instance, calcareous rocks tend to give rise to base-rich soils due to calcification.
It is one of the most deciding factors of the types of soil formation in India. For instance, temperature influences the rate of chemical and biological reactions. On the other hand, precipitation decides the amount of moisture, and the rate of leaching of minerals in the soils types.
It constitutes both the flora and fauna of a region. For example, vegetation checks the soil erosion by binding the soil into their roots.
Topography decides the depth of soil formation. For example, the steep slopes have thinner soil than the gentle slopes.
It is also one of the most significant factors of soil formation as time decides the cycle of recycling of soil and weathering of rocks. For instance, it takes hundreds of years to form a thin layer of soil due to breaking of rocks.
Classification of soil types of India as per USDASoil Taxonomy