Complete Geography Notes on Types of Soils in Bihar for BPSC and Other Competitive Exams in 2025

Complete Geography Notes on Types of soils in Bihar for BPSC and Other Competitive Exams in 2025

Geography-6

Here is a detailed explanation of Types of Soils in Bihar, their distribution, characteristics, and agricultural implications.

Types of Soils in Bihar

Bihar has a diverse soil profile due to its topographical variation, climatic conditions, and river systems. The soils are primarily alluvial, but sandy, red, and laterite soils are also found in specific regions. Here are types of soil having presence in Bihar

• Alluvial Soil: Formed by the deposition of silt and clay by rivers like the Ganges, Gandak, and Kosi, this soil is found extensively in the Bihar plain. It is generally fertile and suitable for agriculture, but regular tillage without proper organic matter input can lead to reduced fertility. 
• Red Soil: Found in certain regions of Bihar, this soil is formed from the weathering of ancient crystalline and metamorphic rocks. It is characterized by a reddish color due to the presence of iron oxides. 
• Laterite Soil: These soils develop in areas with high temperatures and heavy rainfall, leading to the leaching of humus and other essential nutrients. They are typically deficient in organic matter, nitrogen, and phosphate. 
• Saline Soil: Found in arid and semi-arid regions, as well as areas with poor drainage, saline soils are characterized by high acidity and low pH levels, making them unsuitable for many crops. 
• Karail-Kewal Soil: This is a heavy clay soil, often alkaline, found in areas like Rohtas, Gaya, Aurangabad, Jahanabad, Munger, and Bhagalpur, commonly associated with wet paddy lands. 
• Balthar Soil: Found in the Kaimur region of Bihar, this soil type has its own unique characteristics. 
• Tal Soil: This soil type is also found in Bihar, though its specific characteristics and distribution are less widely documented in the provided search results. 
• Piedmont Swamp Soil : This soil type is found in areas where rivers and streams deposit sediment at the base of hills or mountains

Here are the predominant types of soils in Bihar more relevant to

1. Alluvial Soil (Old and New)–

Distribution:

• Covers ~76% of Bihar’s land area
• Found in both North and South Bihar (majority in North)

Types:

1. New Alluvium (Khadar):
   • Found in river floodplains, especially near Ganga, Kosi, Gandak, Bagmati
   • Replenished regularly by silt during floods
   • Light in color, rich in potash, poor in nitrogen
2. Old Alluvium (Bhangar):
   • Found away from active floodplains
   • More clayey and compact
   • Often affected by alkalinity or salinity in patches

Soil Composition:

• Rich in potash and lime
• Deficient in nitrogen and phosphorus

Agricultural Implications:

• Highly fertile – ideal for cereals, pulses, oilseeds, sugarcane
• Supports intensive agriculture
• Requires manure and nitrogenous fertilizers for higher productivity

Districts Covered:

• North Bihar: Muzaffarpur, Sitamarhi, Darbhanga, West Champaran, Saharsa, Supaul
• South Bihar: Patna, Nalanda, Bhojpur, Gaya (partly)

2. Sandy Soil (Kosi Region)

Distribution:

• Found in the Kosi basin, particularly in districts like:
  • Madhepura, Saharsa, Supaul, Purnia, Araria

Formation:

• Deposited by the Kosi River, which carries sand and coarse particles from the Himalayas
• Often a result of floods and riverbed shifts

Soil Composition:

• High sand content, low in organic matter and nutrients
• Porous and has low water-holding capacity

Agricultural Implications:

• Low fertility – unsuitable for high-yielding crops
• Suitable for coarse grains, pulses, and vegetables if irrigated
• Needs organic compost, irrigation, and soil conditioners for improvement

Challenges:

• Prone to drought, wind erosion, and nutrient leaching

3. Red and Laterite Soil (Southern Bihar)

Distribution:

• Found in southern plateau fringe districts, such as:
  • Gaya, Nawada, Jamui, Rohtas, Kaimur, Aurangabad

Formation:

• Result of weathering of ancient igneous and metamorphic rocks
• Found in undulating uplands and forested hills

Soil Composition:

• Red soil: Rich in iron oxide, poor in nitrogen, phosphorus, humus
• Laterite soil: Rich in iron and aluminium; acidic, low fertility

Agricultural Implications:

• Low to medium fertility
• Requires irrigation, liming, and fertilizers for better yield
• Suitable for millets, pulses, oilseeds, and maize
• Laterite soil supports horticulture, e.g., mango, guava, tamarind

Challenges:

• Prone to erosion, especially in sloping areas
• Drought-prone without irrigation

Comparative Table: Soil Types of Bihar

Agricultural Importance of Soils in Bihar

• Northern Plains (Alluvial): Most agriculturally productive; known as the grain bowl of Bihar
• Southern Plateau (Red/Laterite): Less productive; needs soil management for sustainability
• Kosi Region (Sandy): Needs reclamation and better irrigation infrastructure

Likely MCQs