Based on soil characterisation, rainfall, temperature and terrain, four main agro-climatic zones in Bihar have been identified. These are: Zone-I, North Alluvial Plain, Zone-II, north East Alluvial Plain, Zone-III A South East Alluvial Plain and Zone-III B, South West Alluvial Plain, each with its own unique prospects.
North-East Alluvial Plain
➤ This zone is located in the North-East plains. The region has sandy to silty loam soils which are light to medium textured and slightly acidic in nature.
➤ This zone receives 1382 mm average rainfall. It has about 44% land under irrigation.
➤ Maize, jute and pineapple are extensively grown here.
North-West Alluvial Plain
These are Begusarai, East Champaran, West Champaran, Darbhanga, Gopalganj, Madhubani, Muzaffarpur, Samastipur, Saran, Sheohar, Sitamarhi, Siwan, Vaishali.
➤ This North-West zone is extended from Terai region of Himalayas to the Plains of Ganges.
➤ It is the most fertile land of Bihar. Uttar Pradesh state lies to the West of this zone.
➤ It has about 42% land under irrigation. It is a flood prone region.
➤ The zone receives 1,235 mm average rainfall.
➤ Rice, wheat, maize, potato, sugarcane, mango, litchi are major crops of this region.
South Bihar Alluvial Plain
➤ It is located in the Southern Plains. It has alluvial to sandy loam, clayey loam and clay soils. It receives 1,102 mm average annual rainfall.
➤ This zone is divided into two parts such as South-East alluvial plain and South-West alluvial plain.
➤ The maximum irrigation facilities has been developed here.
➤ It has about 75% land under irrigation.
➤ Rice, wheat, potato, gram, mango, guava, etc. crops are extensively grown here.
South East - 6 districts
Sheikhpura, Lakhisarai, Jamui, Banka, Munger and Bhagalpur
South West - 11 districts
Kaimur, Rohtas, Aurangabad, Buxar, Bhojpur, Jehanabad, Gaya, Nalanda, Arwal, Patna, Nawada
North east - 8 districts
Supaul, Khagaria, Saharsa, Madhepura, Purnea, Katihar, Kishanganj, Araria
North West - 13 districts
Saran, Siwan, Gopalganj, E.Champaran, W.Champaran, Sheohar, Sitamarhi, Madhubani, Darbhanga, Muzaffarpur, Vaishali, Samastipur, Begusarai
