Soils of Bihar | Geography of Bihar Notes

Bihar is located on the fertile alluvial plain of Gangetic Valley which extends from the foothills of the Himalayas in the north to a few kilometers south of the river Ganga. 

Due to the Variation in relief, precipitation, vegetation and parent rocks, different types of solid are found in Bihar.

Let’s study about each soil in Bihar in detail.

Types of soils in Bihar: 

Soils in Bihar can be broadly classified into seven categories, which are distributed across the state in different places. 

Piedmont Swamp Soil:

• Found in the North-Western parts of West Champaran district (in the foothills of Himalayas) in Bihar.
• Texture → Mostly clayey.
• Rich in organic matter.
• Major crops cultivated → Paddy.

Terai Soil:

• Terai soil in Bihar is found along the 8-10 km belt of India Nepal border from West Champaran to Kishanganj. 
• Swampy in nature.
• Contains sufficient amount of Nitrogen and humus content.
• Lag in phosphorus.
• Grey to yellow in colour.
• Major crops cultivated →  Wheat, Paddy, sugarcane, jute etc.

Alluvial Soil:

• Found in almost 50% of the total geographical area of the state.
• Formed by deposition of alluvium brought by different rivers.
• Alluvial Soils are of two types:
• Khadar Soil:
  • Newer Alluvium brought by rivers every year. 
  • Mainly found in North Bihar along the basins of Koshi, Ganga, Gandak, Burhi Gandak and other rivers. 
  • Major crops cultivated →   Rice, wheat, sugarcane, jute, tobacco, vegetables, maize and oilseeds.
• Bhangar Soil: 
  • Older alluvium.
  • Found in the upper parts of flood basins of rivers.
  • Also known as Karail-Keval locally.
  • Clayey in nature.
  • Major crops cultivated →  Paddy, wheat, sugarcane, wheat etc.
• Both types of alluvial soils are found in Bihar.

Balasundari Soil:

• Found mainly in Kishanganj, Purnea, Saharsa, Darbhanga, Muzaffarpur and Southern parts of West Champaran district.
• It has a high amount of lime which makes it alkaline in nature
• Generally infertile
• Coarse cereals, maize, tobacco and plantation crops like litchi, banana can be cultivated

Tal Soil:

• Found in an 8-10 km strip along the southern bank of the Ganga river.
• Texture → Fine to coarse.
• Grayish in colour.
• Have similar features as Khadar soil (Newer Alluvial Soil) does have. 
• Major crops cultivated → Rabi crops like wheat, barley, mustard, gram, peas, linseed, and sesame.

Balthar Soil:

• Found from Kaimur to Banka in an 8-15 km wide strip along Chota Nagpur Plateau and Rajmahal Hills.
• Texture → Sandy(Hence low water holding capacity), Yellowish-red in colour. 
• Has a good amount of iron and limestone.
• Lacks in Nitrogen and humus.
• Acidic in nature.
• Major crops cultivated → Pulses and Coarse cereals like Jowar, Bajra etc.

Laterite Soil:

• Generally found in the hilly regions of Bihar.
• Mainly formed as a result of high leaching.
• Leaching occurs when excess water removes water-soluble nutrients out of the soil.
• Rich in iron and aluminum.
• Deficient in Lime and silica(as they are leached away from the soil).
• Less fertile.
• It is infertile but if irrigated it can be fertile.
• It hardens quickly when exposed to air thus useful for making bricks.

Red and Yellow Soil:

• Formed from the disintegration of igneous and metamorphosed rocks. 
• Less fertile.
• Only suitable for coarse crops and pulses. 
• Found in the eastern and southern parts of Bihar like Banka, Gaya, Aurangabad, Jamui and Munger.