Q120. Which soil is dominant in the Great Plains of India?
[RRB NTPC Graduate CBT-I (19 June 2025, Shift 2)]
- (A) Laterite soil
- (B) Black cotton soil
- (C) Alluvial soil
- (D) Red soil
Answer: (C) Alluvial soil
Explanation: India’s Great Plains are an extensive sedimentary lowland formed by river deposition. The deposited sand, silt and clay collectively produce alluvial soil. Its widespread distribution supports farming of rice, wheat, sugarcane and a variety of pulses.
Q119. Black soil occurs predominantly in which region?
[UKPSC Lower PCS Preliminary (11 May 2025)]
- (A) Chota Nagpur Plateau
- (B) Deccan Plateau
- (C) Terai region
- (D) Sundarbans
Answer: (B) Deccan Plateau
Explanation: Regur soil is associated with the Deccan Plateau, where basaltic lava has weathered into dark clay-rich material. This mineral parentage distinguishes it from the Himalayan piedmont, the deltaic Sundarbans and much of the Chota Nagpur region.
Q118. Which major soil type has the alternative name “regur”?
[BSSC Group D (11 May 2025)]
- (A) Mountain soil
- (B) Alluvial soil
- (C) Yellow soil
- (D) Black soil
Answer: (D) Black soil
Explanation: Regur is the traditional name for black cotton soil, especially widespread in the Deccan region. The soil swells when wet, develops cracks during dry weather and retains water efficiently. These properties are important to rainfed cotton cultivation.
Q117. Which statements about saline soils in India are correct? 1. They are rich in nitrogen. 2. They occur in arid and semi-arid regions and in swampy or waterlogged places.
[UPSC CDS-I General Studies (13 April 2025)]
- (A) 1 only
- (B) 2 only
- (C) Both 1 and 2
- (D) Neither 1 nor 2
Answer: (B) 2 only
Explanation: Excess soluble salts characterize saline soils, which occur in arid districts, coastal tracts and poorly drained areas. High salt concentration does not make a soil rich in nitrogen. Such conditions hinder water absorption by plants and may require drainage and careful reclamation.
Q116. Which statements about humus are correct? 1. It is a dark, amorphous material. 2. Its colloidal character allows it to act as a nutrient reservoir.
[UPSC CDS-I General Studies (13 April 2025)]
- (A) 1 only
- (B) 2 only
- (C) Both 1 and 2
- (D) Neither 1 nor 2
Answer: (C) Both 1 and 2
Explanation: Humus is the stable, dark organic matter produced through decomposition of plant and animal residues. Its colloidal particles hold water and nutrients and support soil aggregation. These properties improve fertility and biological activity, making both given descriptions accurate.
Q115. Which pair of crops is particularly well suited to the alluvial soils of the Great Indian Plains?
[RPF Constable 2024 Paper (9 March 2025, Shift 2)]
- (A) Coffee and tea
- (B) Pulses and oilseeds
- (C) Cotton and tobacco
- (D) Rice and wheat
Answer: (D) Rice and wheat
Explanation: River-laid alluvium of the Great Indian Plains forms productive cropland with generally favorable physical properties. Alongside irrigation and a seasonal climate, these soils support intensive rice and wheat farming. The other crop pairs have different principal ecological associations.
Q114. Which statement about black soils in Madhya Pradesh is incorrect?
[MPPSC State Service Prelims (16 February 2025)]
- (A) They form through weathering of Deccan lava
- (B) They are rich in nitrogen, phosphorus and organic matter
- (C) They retain moisture very effectively
- (D) They occur mainly in western Madhya Pradesh
Answer: (B) They are rich in nitrogen, phosphorus and organic matter
Explanation: Black soils in western Madhya Pradesh are derived largely from basalt and are notably moisture-retentive. Although they contain several mineral bases, they are generally deficient in nitrogen, phosphorus and humus. Therefore, describing them as rich in all three is wrong.
Q113. Black soil is comparatively poor in which listed nutrient?
[MPTET Varg 3 (13 November 2024, Shift 1)]
- (A) Lime
- (B) Iron
- (C) Magnesia
- (D) Nitrogen
Answer: (D) Nitrogen
Explanation: The dark soils of the Deccan often contain calcium, magnesium and iron compounds but have relatively low nitrogen and organic matter. Their high clay content gives strong water retention; balanced nutrient management is nevertheless needed for sustained cultivation.
Q112. Which Indian physical feature is associated with lateritic soils and plantation crops?
[SSC MTS (5 November 2024, Shift 1)]
- (A) Chota Nagpur Plateau
- (B) Western Ghats
- (C) Himalayas
- (D) Malabar Coast
Answer: (B) Western Ghats
Explanation: The humid tropical climate and high rainfall of the Western Ghats promote leaching and laterite development. Plantation crops, including tea, coffee and rubber, are cultivated in suitable managed sites. Nutrient depletion and acidity often require careful soil management.
Q111. What term denotes the proportion of pore space in a soil or rock?
[SSC MTS (4 November 2024, Shift 3)]
- (A) Porosity
- (B) Density
- (C) Salinity
- (D) Permeability
Answer: (A) Porosity
Explanation: Porosity measures the volume fraction of voids between particles. Those spaces can contain air or water and strongly affect storage. Permeability is different: it concerns the ease with which fluids can pass through connected pores.
