Sarkari Pariksha

Soils of Bihar

Static GKSoils of Bihar

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Introduction

  • Soil is a key natural resource supporting agriculture, industry, and overall economic activity.
  • Bihar’s plains rest on a thick alluvial cover, deposited over time by rivers from the Himalayas.
  • Most soils here are young alluvial loams, rejuvenated annually by fresh silt, sand, and clay.
  • Deficient in: Nitrogen, Phosphoric acid, Humus
  • Adequate in: Potash and Lime

Major Soil Types in Bihar

Bihar has three main soil categories:

1. Piedmont Swamp Soil

  • Found in: North-western West Champaran
  • Formed in low-lying, swampy piedmont zones below the Siwaliks.
  • High moisture, clayey texture.
  • Very suitable for paddy cultivation.

2. Terai Soil

  • Found along: Indo-Nepal border (northern Bihar)
  • Formed where underground Bhabar streams reappear.
  • Features:
  • Poorly drained, moist, silty, rich in organic matter
  • High in nitrogen, low in phosphate
  • Supports crops like: Rice, Wheat, Sugarcane, Jute
  • Region naturally hosts tall grasses & dense forests.

3. Gangetic Alluvial Soil

Covers almost the entire Bihar plain; the most important soil type.

Formation

  • Deposited by rivers of the Indo-Gangetic system(Ganga, Ghaghara, Gandak, Kosi, Son, Mahananda, Bagmati)

Characteristics

  • Young, porous, loamy soils with weak profile development.
  • Mostly sandy loam to clay loam.
  • Kankar (lime nodules) common in older alluvium.
  • Excellent fertility — constantly renewed by floods.

Chemical Nature

  • Low nitrogen
  • Adequate potash, phosphates, and alkalies
  • Variable iron oxide and lime

Crops

  • Highly productive for:Rice, Wheat, Maize, Lentils, Sugarcane, Jute, Tobacco, Oilseeds, Vegetables, Fruits

Sub-Types of Alluvial Soils

(a) Bhangar (Older Alluvium)

  • Found on higher terraces above flood plains.
  • Darker, more clayey.
  • Contains kankar layers a few meters below the surface.

(b) Khadar (Newer Alluvium)

  • Found on the active floodplains.
  • Replenished annually by river floods.
  • Lighter, sandy, highly fertile — best for agriculture.

Key Features of Bihar’s Soil Profile

  • Formed mostly by riverine deposition.
  • Soil fertility varies but is generally high.
  • Agriculture in Bihar thrives because soils respond well to irrigation.
  • Soil diversity allows cultivation of both Kharif & Rabi