Types of Soil

Types of Soil

Soils of the world is broadly classified into three major categories.

1. Zonal Soil
2. Intrazonal Soil
3. Azonal Soil

Zonal Soil - Soil whose characteristics are dominated by the influence of climate and vegetation is known as Zonal Soil.

1.   Pedalfer Soils 

• They are rich in Aluminum and Iron (Iron oxides).
• Since these soils are formed after a great deal of rainfall, most of the soluble minerals dissolved and are carried away leaving behind less soluble minerals such as Iron Oxides.

Types of Pedalfer Soil 

1. Grey Podzol
• This Soil is found in Taiga Coniferous region of the sub-Arctic climatic zone.
• This is acidic in nature and unsuitable for agriculture.
2. Grey Brown Podzol
• This soil is found in Deciduous forest of the mid latitudes.
• This soil is rich in humus. It remains fertile by using manures, fertilizers and crop rotation.
3. Red Yellow Podzol
• This soil is formed by the process of Podzoisation and laterisation in the sub-tropical climatic region.
• This soil is devoid of humus.
4. Red Podzol or Terra Rossa
• This soil is found in Mediterranean and lime region.
• It is red in colour due to the presence of Iron Oxide.
• It is also devoid of humus.
5. Laterite Soil
• This soil is formed in the regions of high temperature, abundant rainfall and equatorial forests where the process of leaching is dominant.
• Due to excessive leaching Salts of Aluminum and Iron are found in the upper layers of the soil.

2.   Pedocal Soils 

• They are rich in Calcium.
• They are formed in drier temperate areas where grassland and bushes are the usual type of vegetation.

Types of Pedocal Soil 

1. Prairie Soil or Mollisols 
• These are found in the wet temperate tall grass regions.
• Its colour is brown black and is rich in humus.
• Regions - Prairie region of USA, Pampas of South America, Pustaz of Hungary and Downs of Australia.
2. Chernozem 
• It is found in the Steppe region.
• It is black in colour due to the abundance of humus.
• Lime is found in the bulk in its lower layers.
3. Chestnut 
• It is dark brown soil found in the drier parts of chernozem region.
4. Red Chestnut or Red Brown Soil 
• This soil is found in the semi-arid areas of the Savanna region.
5. Sierozems 
• This soil is found in the hot deserts of mid-latitudes.
• Lime forms a deposition over the upper layer of the soil.
6. Red Desert Soil 
• This soil is found in the hot deserts of tropical region.
• It is characterised by the deposition of lime near the surface and the absence of humus.
7. Soil of Tundra Region 
• It is highly under-developed soil having a deficiency of humus and important minerals.
• They are found in the Tundra regions (very cold climate).

Intra Zonal Soils - Soils which have more or less well defined soil profile characteristics that reflect the dominant influence of some local factors such as effective drainage, evaporation or parent rock material over climate and vegetation.

Types of Intra Zonal Soils 

1. Hydromorphic Soil - This includes pit, grasslands, fields and pleno solo soils.
2. Halomorphic Soil - This has Saline, Solonetz and Soloth Soils.
3. Calcimorphic Soil - This soil includes Rendzina, Terrarossa and Terarokes Soils.

Azonal Soils - This soil has not been sufficiently subjected to soil forming process for the development of a mature profile and so is little changed from the parent rock material.

Azonal Soils do not have B-Horizon because it is too immature. Thus, A-Horizon lies immediately above the C-Horizon.

Types of Azonal Soil 

1. Lithosol Soil - This soil has more small rocks in it. Soils of Bhabar region, foot hill zone and rocky soil are lithosol soil.
2. Regosol Soil - This consist of Alluvial, Leptosols and Arenosols soils.

Soil Taxonomy - A new detailed classification of soil has been prepared by the scientists of the USA in 1960 known as Comprehensive Soil Classification System (CSCS), also known as Soil Taxonomy.

Underdeveloped Soil -

• Entisol
• Inceptisol
• Histosol

Developed Soil -

• Oxisol
• Ultisol
• Vertisol
• Alfisol
• Spodosol
• Mollisol
• Aridosol

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Note - This is my Vision IAS Notes (Vision IAS Class Notes) and Ashutosh Pandey Sir's Public Administration Class notes. I've also added some of the information on my own. 

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