Assertion (A) : The Gangetic plains are among the most bountiful agricultural areas of the world. Reason (R) : The Gangetic plains contain predominantly regursoil.

Assertion (A) is true as the Gangetic plains are globally recognized as highly productive agricultural regions [t2][t7]. This fertility is primarily due to the deposition of alluvium by the Ganga and its tributaries, which is rich in organic matter and rejuvenated through periodic flooding [t1][t3]. Reason (R) is false because the Gangetic plains are characterized by alluvial soils (Khadar and Bhangar), not regur soil [c2][t6]. Regur soil, also known as black cotton soil, is typical of the Deccan Trap region in the northwest Deccan plateau, covering states like Maharashtra, Gujarat, and Madhya Pradesh [c1][t4]. It is formed from the weathering of basaltic lava rocks rather than riverine deposition [c3][t4]. Therefore, while the plains are indeed bountiful, the soil responsible for this productivity is alluvium, making the reason provided scientifically incorrect.

Sources

1. [1] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 1: The Rise of Nationalism in Europe > Black Soil > p. 9
2. [2] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 6: Soils > Table 6.1 > p. 6
3. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 6: Soils > 3. Black or Regur Soils > p. 11
4. [4] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/alluvial-soil
5. [5] https://en.wikipedia.org/wiki/Major_soil_deposits_of_India