• Soil is the uppermost layer of the earth's crust that supports plant growth and provides nutrients, water and air to living organisms.
• Soil can be classified into different types based on various factors such as texture, structure, colour, depth, fertility, water content, organic matter, pH and temperature.
• The main types of soil are: sandy soil, clayey soil, loamy soil, laterite soil, black soil, red soil, alluvial soil and desert soil.

Alluvial soils

• Widely spread and important soil.
• Entire region of the northern plain is made up of alluvial soil.
• Deposited by the Indus, the Ganga and the Brahmaputra.
• Through a narrow corridor these soil extends in Rajasthan and Gujarat.
• Found in Eastern coastal plains.
• Old alluvial soil is called Bangar and new is called Khadar.
• Alluvial soil is very fertile.
• Rich in potash, phosphoric acid and lime.
• Regions of alluvial soil are intensely cultivated and densely populated.

Black soil

• Black soil is also known as regur soils .
• Black soil is considered ideal for growing cotton and is also known as black cotton soil.
• Climate conditions and parent rock materia l are key factors for the formation of black soil.
• This soil is typical of the Deccan trap (Basalt region) which is spread over northwest Deccan plateau.
• This soil is made up of lava flows.
• Black soil covers the plateau of Maharashtra , Saurashtra , Malwa , Madhya Pradesh and Chhattisgarh and extends in the southeast direction along the Godavari and Krishna Valleys.
• Black soil is made up of clayey material.
• Black soil is known for its capacity to hold moisture.
• Black soi l is rich in nutrients such as calcium carbonate , magnesium, potash and lime.
• Black soil lacks phosphoric content.
• During hot weather this soil develops deep cracks which helps in proper aeration of the soil .
• When wet black soil turns very sticky and is difficult to work on if not tilled immediately after the first shower or pre monsoon period.

Red and Yellow Soils

• Red soi l develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern parts of the Deccan plateau.
• Red and Yellow soils are also found in the parts of Odisha, Chhattisgarh, Southern parts of the middle Ganga plain and along the piedmont zone of the Western Ghats.
• These soils develop a reddish color due to diffusion of iron in crystalline and metamorphic rocks.
• The soil looks yellow when it occurs in a hydrated form.

Laterite Soil

• Laterite word has been derived from the Latin word ‘later ’ meaning brick.
• Laterite soil develops and is found in areas with high temperatures and heavy rainfall.
• Formation of Laterite soil is a result of intense leaching due to heavy rains.
• The content of Humus in the laterite soil is low because most of the microorganisms , mainly the decomposers like bacteria , get destroyed because of high temperature.
• For cultivation on laterite soil adequate amounts of manures and fertilizers are required.
• Laterite soil is mainly found in Karnataka, Kerala , Tamil Nadu , Madhya Pradesh , and the hilly areas of Odisha and Assam.
• Laterite soil becomes very useful for growing tea and coffee after adopting appropriate conservation techniques particularly in the hilly areas of Karnataka, Kerala and Tamil Nadu.
• Laterite soils found in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for the cultivation of crops like cashew nuts.

Arid Soils

• Arid soils range from red to brown in color.
• Arid soils are sandy in texture and saline in nature.
• In some areas the amount of salt is very much which is then used in obtaining salt by evaporating the water.
• Because of dry climate , high temperature with more rate of evaporation the soil lacks humus and moisture.
• In Arid soil the lower horizons of the soil are occupied with Kankar because of increase in calcium content downwards.
• The Kankar layer formation in the bottom horizon restricts the infiltration of water.
• Arid soils become cultivable after proper irrigation as has been in the case of Western Rajasthan.

Forest Soils

• These soils are available in hilly and mountainous areas where sufficient rain forests are available.
• The texture of the forest soils varies according to the mountain environment where they are formed.
• They are coarse grained in the upper slopes and loamy and silty in valley sides.
• In the snow covered areas of Himalayas , the forest soils experience denudation and are acidic in nature and contain low amounts of Humus .
• The forest soils found in the lower parts of valleys especially on the river terraces and alluvial fans are fertile.

Major soil types found in India