Soil Types of India — Set 1

Correct Answer: B. Alluvial soil

Alluvial soil is the most widespread soil type in India, covering about 40-45% of the total land area. It is primarily found in the Indo-Gangetic plains, extending from Punjab in the west to Assam in the east. This soil is extremely fertile and supports the cultivation of a wide variety of crops. It is formed by the deposition of sediments carried by rivers.

Correct Answer: C. Regur

Black soil is commonly known as Regur soil in India, a term derived from the Telugu word 'reguda'. It is also called Black Cotton Soil because it is ideal for cotton cultivation. This soil is found mainly on the Deccan Plateau. It is formed from the weathering of volcanic basalt rocks.

Correct Answer: D. Bhangar

Bangar (also spelled Bhangar) is the older type of alluvial soil found at higher elevations, away from active flood plains. It is less fertile than Khadar because it is not replenished regularly by river floods. Bangar soil contains lime nodules called Kankar and is coarser in texture. It is found in the upland areas of the Indo-Gangetic plains.

Correct Answer: C. Khadar

Khadar is the newer type of alluvial soil found in the active flood plains close to river channels. It is renewed annually during the flood season, which makes it more fertile than Bangar. Khadar soil is finer in texture and lighter in colour. It supports intensive cultivation of rice, wheat, sugarcane, and other crops.

Correct Answer: C. Nitrogen

Alluvial soil in India is generally deficient in nitrogen and humus. Despite being highly fertile for many crops, it lacks sufficient organic nitrogen content. Phosphorus content in alluvial soil is relatively adequate. Farmers need to apply nitrogenous fertilizers to maximize crop yields on alluvial soils.

Correct Answer: D. Volcanic basalt

Black soil, or Regur soil, is formed by the weathering of volcanic basalt rocks of the Deccan Plateau. The dark colour of this soil is due to the presence of titaniferous magnetite and compounds of iron and aluminium. The process of weathering over millions of years has created this characteristic dark-coloured soil. This volcanic origin gives the soil its high clay content and moisture-retaining properties.

Correct Answer: C. Cotton

Cotton is the best crop grown in Black soil, which is why it is also called Black Cotton Soil. The high moisture-retaining capacity of Black soil is ideal for cotton cultivation. Cotton requires a well-drained but moisture-retentive soil, which Black soil provides naturally. States like Maharashtra, Gujarat, and Madhya Pradesh are major cotton producers on Black soil.

Correct Answer: B. It swells when wet and shrinks and cracks when dry

Black soil has a unique self-ploughing property — it swells when wet and shrinks and develops deep cracks when dry. These cracks allow the lower layers to be aerated and organic matter to be incorporated into the soil. This property is called self-ploughing or auto-ploughing. The high content of montmorillonite clay is responsible for this shrink-swell behaviour.

Correct Answer: C. West Bengal

West Bengal is not a major Black soil region; it is primarily known for alluvial soil. Black soil is predominantly found in Maharashtra, Madhya Pradesh, Karnataka, Andhra Pradesh, Telangana, and parts of Gujarat. The Deccan Plateau is the heartland of Black soil distribution. West Bengal's fertile soils are mainly of the alluvial type deposited by rivers like the Ganga.

Correct Answer: B. Calcium, magnesium, and potassium

Black soil is rich in calcium, magnesium, and potassium, which contribute to its fertility for certain crops. However, it is deficient in nitrogen, phosphorus, and organic matter. The presence of these minerals makes it suitable for crops like cotton, soybean, and sorghum. Despite its mineral richness, nitrogen and phosphorus fertilizers must be added for optimal crop production.