Explanation:

West Champaran 

• Piedmont Swamp Soil is predominantly located in the northwestern region of West Champaran district in Bihar.
• The predominant soil type across Bihar is Gangetic alluvium, typical of the Indo-Gangetic plain.
• Terai Soil is prevalent in the northern part of Bihar, bordering Nepal.
• Bihar also features a variety of soils including sandy, clay, and loamy soils.
• However, these soils often exhibit deficiencies in nitrogen, phosphoric acid, and humus, while typically containing sufficient quantities of lime and potash.