Environmental Studies · Geography

Soil Science

1,499 Questions

Soil Science examines the formation, classification, and properties of soil as a critical natural resource. This hub offers practice questions covering soil horizons, soil types like laterite and black soil, and regional soil characteristics. The content is highly useful for agriculture exams and civil services preparation.

Soil typesSoil horizonsSoil formation factorsAgricultural soil requirementsIndian soilsForest and mountain soils

Soil Science Questions

Multiple choice

Which of the following statements is/are correct?

a. Black soils swell and become sticky when wet and shrink when dried. b. Black soils are generally clayey, deep and impermeable. c. Black soils are rich in phosphorus, nitrogen and organic matter.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. a, b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the correct answer as both the statements are correct. Black soils swell and become sticky when wet and shrink when dried. Black soils are generally clayey, deep and impermeable.

Multiple choice

Which of the following statements is/are correct?

a. Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern parts of the Deccan plateau. b. Red soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks. c. The fine grained red and yellow soils are normally infertile.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the correct answer as both these statements are correct. Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern parts of the Deccan plateau. Red soil develops a reddish colour due to a wide diffusion of iron in crystalline and metamorphic rocks.

Multiple choice

Which of the following statements is/are incorrect?

a. Laterite soils are poor in organic matter, nitrogen, iron oxide and potash. b. Nitrogen is insufficient in arid soils and the phosphate content is normal. c. Red and yellow soils are rich in lime, iron, magnesia and alumina.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. a and c
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct answer as both these statements are incorrect. Laterite soils are poor in organic matter, nitrogen, phosphate and calcium, while iron oxide and potash are in excess. Black soils are rich in lime, iron, magnesia and alumina.

Multiple choice

Which of the following statements is/are correct?

a. Forest soils are loamy and silty on valley sides. b. Forest soils are coarse grained in the upper slopes. c. The soils in the snow-bound areas of the Himalayas are saline with high potassium content.

  1. a only

  2. b only

  3. c only

  4. a and b

  5. a, b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the correct answer as both these statements are correct. Forest soils are loamy and silty on valley sides. Forest soils are coarse grained in the upper slopes.

Multiple choice

There is a kankar layer in the lower horizons of the arid soils. Which of the following statements is/are correct about this layer?

a. Lower horizons of the soil are occupied by ‘kankar’ layers because of the increasing calcium content downwards. b. It restricts the infiltration of water, and when irrigation is made available, the soil moisture is readily available for a sustainable plant growth. c. It restricts the infiltration of water, and even when irrigation is made available, the soil remains infertile.

  1. a and b

  2. a and c

  3. a only

  4. b only

  5. c only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct answer as both these statements are correct. Lower horizons of the soil are occupied by ‘kankar’ layers because of the increasing calcium content downwards. It restricts the infiltration of water, and when irrigation is made available, the soil moisture is readily available for a sustainable plant growth.

Multiple choice

The use of gypsum is recommended mainly in soils which are

  1. alkaline

  2. saline

  3. water-logged

  4. acidic
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gypsum (calcium sulfate) is used to reclaim alkaline soils. The calcium ions in gypsum replace sodium ions on the soil particles, which helps improve soil structure and reduce alkalinity.

Multiple choice

Which of the following is/are the characteristic(s) of laterite soil?

(a) It does not retain moisture well. (b) It is rich in humus. (c) It is acidic in nature. (d) It is found predominantly in coastal areas.

  1. Both (a) and (b)

  2. Only (b)

  3. Only (a)

  4. Only (c)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Laterite soil is acidic in nature. Laterites are soil types rich in iron and aluminium, and formed in hot and wet tropical areas. Nearly all laterites are rusty-red because of iron oxides. They are developed by intensive and long-lasting weathering of the underlying parent rock.

Multiple choice

Intense evaporation causes saline soil. Such soil can be expected in

  1. Tropical desert region

  2. Equatorial region

  3. The prairies

  4. Deltas
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Intense evaporation causes saline soil. Such soil can be expected in tropical desert region. In tropical desert region the soils tend to be sandy, rocky and have low organic matters. Such soils causing intense evaporation are saline soils. 

Multiple choice

Red soil is primarily found in

  1. Punjab, Haryana, Himachal Pradesh

  2. Tamil Nadu, Andhra Pradesh, Karnataka

  3. Assam, Meghalaya, Tripura

  4. Uttar Pradesh, Madhya Pradesh, Bihar
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Red soil is primarily found in Tamil Nadu, Andhara Pardesh and Karnataka. Red soil is mostly found in Tamil Nadu, Karnataka, parts of Maharashtra, Andhra Pradesh, MP, Orissa and Jharkhand. Crops such as cotton, wheat, rice, millets, pulses and tobacco can be grown in it. 

Multiple choice

Black soil is mainly found in India in

  1. Punjab, Haryana and Himachal Pradesh.

  2. Kerala, Karnataka, Orissa and Tamil Nadu.

  3. Madhya Pradesh, Gujarat, Tamil Nadu, Karnataka.

  4. W. Bengal, Kerala, Goa and Tamil Nadu.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Black soil is mainly found in India in Madhya Pradesh, Gujarat, Tamil Nadu, and Karnataka. Black soil is black in color. It has been formed from lava rocks. It is also called black lava soil. Black soil is found in Deccan Trap which covers large areas of Maharashtra, Gujarat and Madhya Pradesh. It is suitable for cotton, sugarcane, wheat, millets, tobacco and oilseeds. 

Multiple choice

Ideal NPK ratio for Indian soils is ………………

  1. 4 : 2 : 1.

  2. 3 : 2 : 1

  3. 4 : 3 : 1

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The ideal ratio of Nitrogen, Phosphorus, and Potassium (NPK) for Indian soils is generally considered to be 4:2:1. This is a standard recommendation in Indian agricultural science.