The question asks to identify the most widespread and agriculturally productive soil group in India. This requires knowledge of the major soil types in India, their distribution, and their suitability for agriculture.
D) Alluvial soil is the most widespread and agriculturally significant soil group in India. It covers about 40% of the total land area and is formed by the deposition of sediments by rivers. These soils are highly fertile, rich in potash, phosphoric acid, and lime, making them ideal for growing a variety of crops like wheat, rice, sugarcane, and pulses. The Indo-Gangetic plains, formed by these soils, are the granaries of India.
The question asks about the primary agents responsible for depositing the alluvial soils of the Northern Plains of India. This requires knowledge of the geographical formation and geological processes of this region.
The Northern Plains are primarily formed by the depositional work of the Himalayan rivers (Indus, Ganga, Brahmaputra, and their tributaries). These rivers carry vast amounts of alluvium from the mountains and deposit it as they enter the plains, creating fertile soil.
The question asks for the classification of alluvial soils based on age. Alluvial soils are deposited by rivers and are broadly categorized into two types based on their age and characteristics.
Correct Option: D) Bhangar and Khadar are the two divisions of alluvial soils based on their age. Bhangar is the older alluvial soil, and Khadar is the newer alluvial soil.
The question asks to identify a key characteristic of Khadar alluvium. To answer this, we need to understand the differences between Khadar and Bhangar alluvium, which are the two main types of alluvial soils found in the Indo-Gangetic plains.
Correct Option: C) It is fresh deposit, light coloured and more fertile. This option accurately describes the key characteristics of Khadar alluvium, which is the new alluvium deposited annually by floods, making it highly fertile and generally lighter in color.
The question asks to identify a distinguishing feature of Bhangar soils. This requires knowledge of the characteristics of different types of alluvial soils found in India.
D) Calcareous concretions known as 'kankar'
Bhangar soils are characterized by the presence of 'kankar' nodules, which are lumps of calcium carbonate. These concretions are formed due to the accumulation of calcium salts in the older alluvial deposits, making the soil less fertile and harder to cultivate than Khadar soils.
The question asks about the variation in texture of alluvial soils in India, specifically how it changes from the upper to the lower reaches of the river plains. Alluvial soils are formed by the deposition of sediments by rivers, and the texture of these sediments changes with the flow velocity and distance from the source.
Correct Option: D) From sandy loam and clay in the upper to lower reaches respectively