2. Give the detailed information about the Alluvial soil and Black soil of Indi
1) Alluvial soil of India :
Answers
Answer:
Soil Types of India – Alluvial Soils – Black Soils – Characteristics, Chemical properties, Distribution, Divisions: Bhabar, Terai, Bhangar, Khadar.
Major Soil Types of India
Geologically, Indian soils can broadly be divided into soils of peninsular India and soils of extra-peninsular India.
The soils of Peninsular India are formed by the decomposition of rocks in situ, i.e. directly from the underlying rocks.
Soils of Peninsular India are transported and re-deposited to a limited extent and are known as sedentary soils.
The soils of the Extra-Peninsula are formed due to the depositional work of rivers and wind. They are very deep. They are often referred to as transported or azonal soils.
Major groups:
Alluvial soils,
Black soils,
Red soils,
Laterite and Lateritic soils,
Forest and Mountain soils,
Arid and Desert soils,
Saline and Alkaline soils and
Peaty and Marshy soils.
Soil Types - Major Soil Groups of India
Alluvial Soils
Alluvial soils are formed mainly due to silt deposited by Indo-Gangetic-Brahmaputra rivers. In coastal regions some alluvial deposits are formed due to wave action.
Rocks of the Himalayas form the parent material. Thus the parent material of these soils is of transported origin.
They are the largest soil group covering about 15 lakh sq km or about 46 per cent of the total area.
They support more than 40% of the India’s population by providing the most productive agricultural lands.
Characteristics of Alluvial Soils
They are immature and have weak profiles due to their recent origin.
Most of the soil is Sandy and clayey soils are not uncommon.
Pebbly and gravelly soils are rare. Kankar (calcareous concretions) beds are present in some regions along the river terraces.
The soil is porous because of its loamy (equal proportion of sand and clay) nature.
Porosity and texture provide good drainage and other conditions favorable for agriculture.
These soils are constantly replenished by the recurrent floods.
Chemical properties of Alluvial Soils
The proportion of nitrogen is generally low.
The proportion of Potash, phosphoric acid and alkalies are adequate
The proportion of Iron oxide and lime vary within a wide range.
Distribution of Alluvial Soils in India
They occur all along the Indo-Gangetic-Brahmaputra plains except in few places where the top layer is covered by desert sand.
They also occur in deltas of the Mahanadi, the Godavari, the Krishna and the Cauvery, where they are called deltaic alluvium (coastal alluvium)
Some alluvial soils are found in the Narmada, Tapi valleys and Northern parts of Gujarat.
Crops in Alluvial Soils
They are mostly flat and regular soils and are best suited for agriculture.
They are best suited to irrigation and respond well to canal and well/tube-well irrigation.
They yield splendid crops of rice, wheat, sugarcane, tobacco, cotton, jute, maize, oilseeds, vegetables and fruits.
Geological divisions of alluvial soils
Geologically, the alluvium of the Great plain of India is divided into newer or younger khadar and older bhangar soils.
Bhabar
The bhabar belt is about 8-16 km wide running along the Shiwalik foothills. It is a porous, northern most stretch of Indo-Gangetic plain.
Rivers descending from the Himalayas deposit their load along the foothills in the form of alluvial fans. These alluvial fans (often pebbly soils) have merged together to build up the bhabar belt.
The porosity of bhabar is the most unique feature. The porosity is due to deposition of huge number of pebbles and rock debris across the alluvial fans.
The streams disappear once they reach the bhabar region because of this porosity. Therefore, the area is marked by dry river courses except in the rainy season.
The area is not suitable for agriculture and only big trees with large roots thrive in this belt.
Terai
Terai is an ill-drained, damp (marshy) and thickly forested narrow tract (15-30 km wide) to the south of Bhabar running parallel to it.
The underground streams of the Bhabar belt re-emerge in this belt. It is a swampy lowland with silty soils.
The terai soils are rich in nitrogen and organic matter but are deficient in phosphate.
These soils are generally covered by tall grasses and forests but are suitable for a number of crops such as wheat, rice, sugarcane, jute etc..
This thickly forested region provides shelter to a variety of wild life.
Bhangar
The Bhangar is the older alluvium along the river
Black Soils
The parent material for most of the black soil are the volcanic rocks that were formed in the Deccan Plateau (Deccan and the Rajmahal trap).
In Tamil Nadu, gneisses and schists form the parent material. The former are sufficiently deep while the later are generally shallow.
These are the region of high temperature and low rainfall. It is, therefore, a soil group typical to the dry and hot regions of the Peninsula.
Explanation:
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Answer:
Alluvial Soils
Formation: They are mainly derived from the debris brought down from the Himalayas or the silt left out by the retreating sea. Thus they are azonal soils.
Areas: Alluvial soils are widespread in the northern plains and the river valleys. Through a narrow corridor in Rajasthan, they extend into the plains of Gujarat. In the Peninsular region, they are found in deltas of the east coast and in the river valleys.
Soil texture: The alluvial soils vary in nature from sandy loam to clay. These soils are more loamy and clayey in the lower and middle Ganga plain and the Brahmaputra valley. The sand content decreases from the west to east.
Soil Colour: The colour of the alluvial soils varies from the light grey to ash grey depending on the depth of the deposition, the texture of the materials, and the time taken for attaining maturity.
Other Characteristic Features:
In the Upper and Middle Ganga plain, two different types of alluvial soils have developed, viz. Khadar and Bhangar.
Khadar and Bhangar
Khadar: the newer alluvium deposited by floods annually, enriches the soil by depositing fine silts, light colour, found near river beds, porous in nature.Bhangar: older alluvium, clayey, darker, has lime nodules called Kankars, found in doabs (inter-fluve areas).
Alluvial soils of the northern plains —> transported soils —> therefore lack humus —> lack nitrogen [That is why we need to use nitrogenous fertilisers in the northern plains!]. Exception: the Ganga-Brahmaputra delta region is rich in humus.
These soils lack in nitrogen, phosphorus and humus. However, they are generally rich in potash and lime.
The soil profile has no stratification.
Alluvial soils are intensively cultivated.
In certain areas, these soils are covered with unproductive wind-borne soil called Loess.
Limitations:
Allow water to sink into lower strata, and
Lack nitrogen (But these soils are capable of fixing nitrogen very rapidly through leguminous crops (peas, beans, cloves etc.)
Suitable Crops: Wheat, rice, maize, sugarcane, pulses, oilseeds, fruits and vegetables, leguminous crops.
2. Black Soil
These soils are locally known as the ‘Regur Soil’ or the ‘Black Cotton Soil’. Internationally, these are known as ‘tropical chernozems’. These soils are famous for the cultivation of cotton.
Formation: These have mainly formed from the Deccan Trap rocks —> Zonal Soils
Areas: These are found in the Deccan trap region. Black soil covers most of the Deccan Plateau which includes parts of: