Soils Archives

1. Which one among the following statements for black soil is not

Which one among the following statements for black soil is *not* correct?

It is also known as 'regur soil'.

It is generally clayey and impermeable.

It swells when wet and shrinks when dry.

It cannot retain water for long time.

This question was previously asked in

UPSC CBI DSP LDCE – 2023

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The statement that is NOT correct about black soil is D. Black soil has a high clay content, which gives it excellent moisture retention capacity. It can retain water for a long time.

Black soil is known for its moisture retention capability due to its clayey nature. The other statements are correct characteristics of black soil.

Black soil is also called Regur soil or Black Cotton soil because it is ideal for cotton cultivation. It is rich in minerals like calcium carbonate, magnesium, potash, and lime, but poor in nitrogen and phosphorus. It develops cracks during dry periods, which helps in aeration.

2. The black cotton soil of India has been formed due to the weathering

The black cotton soil of India has been formed due to the weathering of

brown forest soil

fissure volcanic rock

granite and schist

shale and limestone

This question was previously asked in

UPSC IAS – 2021

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The correct answer is B) fissure volcanic rock.

– The black cotton soils of India, also known as Regur soils, are predominantly found in the Deccan Plateau region.
– These soils are formed by the weathering of basaltic lava rocks, which are the result of massive fissure volcanic eruptions that occurred during the formation of the Deccan Traps in the late Cretaceous period.
– Basalt is a type of extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon.

– Black cotton soils are rich in clay minerals like montmorillonite, which causes them to swell when wet and shrink when dry, leading to characteristic cracks. They are known for their fertility and suitability for cotton cultivation, hence the name.
– Weathering of granite and schist typically produces red or yellow soils (e.g., in the Peninsular Plateau).

3. Which of the following statements regarding laterite soils of India ar

Which of the following statements regarding laterite soils of India are correct?

They are generally red in colour.
They are rich in nitrogen and potash.
They are well-developed in Rajasthan and UP.
Tapioca and cashew nuts grow well on these soils.

Select the correct answer using the codes given below.

1, 2 and 3

2, 3 and 4

1 and 4

2 and 3 only

This question was previously asked in

UPSC IAS – 2013

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The correct answer is C) 1 and 4. Statements 1 and 4 regarding laterite soils are correct, while statements 2 and 3 are incorrect.

Laterite soils are formed under conditions of high temperature and heavy rainfall, leading to intense leaching. This process removes silica but leaves behind iron and aluminium oxides, which give the soil its characteristic red colour (Statement 1). These soils are generally poor in nutrients like nitrogen, potash, lime, and organic matter (Statement 2 incorrect). They are found in specific regions experiencing such climate, primarily in the Western and Eastern Ghats, parts of southern Maharashtra, Karnataka, Kerala, Tamil Nadu, Odisha, etc., not typically Rajasthan and UP (Statement 3 incorrect). Despite being infertile, certain crops like tapioca and cashew nuts grow well on them with appropriate fertilization (Statement 4).

Laterite soil is derived from laterite rock, which is rich in iron and aluminium. The term “laterite” is derived from the Latin word ‘later’ meaning brick, as these soils can harden significantly when dried and are often used for building purposes. Tea and coffee are also important crops grown in regions with laterite soils.

4. Consider the following statements: 1. Black soil is considered suita

Consider the following statements:

1. Black soil is considered suitable for growing rain-fed crops
2. Black soil can retain moisture for a prolonged period, aiding crops to survive even in dry seasons

With regard to the statements given above which of the following is/are correct ?

Both the statements are correct and statement 2 is the correct explanation of statement 1

Both the statements are correct and statement 2 is NOT the correct explanation of statement 1

Statement 1 is correct but statement 2 is false

Statement 1 is false but statement 2 is correct

This question was previously asked in

UPSC CAPF – 2024

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The correct answer is A) Both the statements are correct and statement 2 is the correct explanation of statement 1.

Black soil, also known as Regur soil or Vertisol, is characterized by its high clay content and resulting high moisture retention capacity. This property is particularly beneficial for agriculture in areas that rely on rainfall (rain-fed crops), as the soil can store water and provide it to crops during dry periods. Statement 1 correctly identifies black soil as suitable for rain-fed crops, and statement 2 correctly states its ability to retain moisture for prolonged periods, which directly explains its suitability for rain-fed agriculture by mitigating the effects of dry spells.

Black soil is formed from the weathering of basaltic rocks and is common in the Deccan Trap region of India. It is rich in minerals like iron, magnesium, and lime but deficient in nitrogen, phosphorus, and organic matter. Crops like cotton, sugarcane, jowar, bajra, and groundnut are widely grown in black soils under rain-fed conditions. The high clay content causes black soil to swell when wet and shrink when dry, leading to the formation of cracks, which helps in aeration.

5. Which of the following soil formation process takes place in Phumdis (

Which of the following soil formation process takes place in Phumdis (floating fields) in Loktak Lake of Manipur ?

Laterization

Podzolization

Gleization

Calcification

This question was previously asked in

UPSC CAPF – 2023

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Phumdis in Loktak Lake are unique floating islands composed of vegetation, soil, and organic matter. They exist in a waterlogged, anaerobic environment. Gleization is a soil formation process that occurs under prolonged waterlogged (anaerobic) conditions. It involves the reduction of iron compounds, often resulting in characteristic grayish or bluish-gray colors in the soil profile. This process is typical in wetlands and swamps, fitting the environment of the Phumdis. Laterization occurs in hot, humid climates with intense leaching. Podzolization occurs in cool, humid climates under coniferous forests. Calcification occurs in arid/semi-arid climates with calcium carbonate accumulation. Therefore, gleization is the most relevant soil formation process associated with the waterlogged conditions where Phumdis develop.

Gleization is a soil-forming process characteristic of poorly drained or waterlogged environments like wetlands, involving the reduction and segregation of iron and manganese under anaerobic conditions.

Phumdis cover a significant portion of Loktak Lake and are crucial to the ecosystem. The Keibul Lamjao National Park, home to the endangered Sangai (Brow-antlered deer), is situated on the largest phumdi.

6. Consider the following statements about Laterite soil found in India :

Consider the following statements about Laterite soil found in India :

1. Laterite soil is found in high altitudes of Himalaya.
2. It is a very fertile soil.
3. It is a red colour soil due to presence of iron oxide.
4. It is poor in Nitrogen, Potash and organic matter.

Which of the statements given above is/are correct ?

3 only

2 and 4 only

3 and 4 only

1, 3 and 4

This question was previously asked in

UPSC CAPF – 2023

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Statement 3 is correct: Laterite soil is indeed red in colour due to the high content of iron oxides, particularly hydrated iron oxides. Statement 4 is correct: Laterite soils are generally poor in essential plant nutrients like Nitrogen, Potash, Lime, and organic matter because of intense leaching in heavy rainfall areas. Statement 1 is incorrect: Laterite soils are formed under conditions of high temperature and heavy rainfall with alternate wet and dry spells, leading to intense leaching (laterization). These conditions are typically found in the Western Ghats, Eastern Ghats, North-Eastern India, and parts of Odisha and other states, but not generally in the high altitudes of the Himalayas which have different climatic and soil formation processes. Statement 2 is incorrect: Laterite soil is generally infertile for agriculture due to the removal of most nutrients by leaching. It can support crops like cashew, tea, coffee, and tapioca with the application of manures and fertilizers.

Laterite soils are characterized by intense leaching under hot and humid tropical climates, resulting in iron and aluminium rich composition, redness from iron oxides, and poor fertility due to lack of essential nutrients and organic matter. They are not typically found in high altitudes of the Himalayas.

Laterite soil is derived from the laterite rock, which gets its name from the Latin word ‘later’, meaning brick. These soils are suitable for brick making due to their hardening when exposed to air. Specific crops like cashew nuts, tea, coffee, and tapioca are grown in laterite soils with proper management.

7. Regur soil is most suitable for the cultivation of :

Regur soil is most suitable for the cultivation of :

Groundnut

Cotton

Tobacco

Sugarcane

This question was previously asked in

UPSC CAPF – 2015

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Regur soil is the local name for Black soil found in India, particularly in the Deccan Trap region. These soils are known for their high clay content and ability to retain moisture, making them very fertile for certain crops, especially cotton. Black soil is often referred to as “black cotton soil” due to its suitability for cotton cultivation.

Regur soil is synonymous with Black soil in India and is derived from weathering of volcanic rocks. Its key characteristic is its moisture-retentive capacity and high fertility for cotton.

While black soils can also be used for other crops like sugarcane, groundnut, jowar, etc., cotton is the most prominently associated crop with Regur soil because of the soil’s unique properties that suit cotton cultivation well, such as its ability to retain moisture during dry spells.

8. Which one among the following is not correct regarding the black soi

Which one among the following is *not* correct regarding the black soils of Peninsular India?

Rich in iron, lime and potash

Retentive in moisture

Fertile and well-suited for growing sugarcane

Rich in phosphorus and organic matter

This question was previously asked in

UPSC CAPF – 2013

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The statement that black soils are rich in phosphorus and organic matter is incorrect.

Black soils (Regur) are derived from weathering of basaltic rocks (Deccan Traps) and are rich in minerals like iron, lime, calcium, potash, aluminium, and magnesium. They have a high clay content, which gives them excellent moisture retention capacity. They are generally fertile and suitable for crops like cotton, sugarcane, groundnut, tobacco, and millets. However, they are typically deficient in nitrogen, phosphorus, and organic matter (humus).

The deficiency in phosphorus and organic matter means that these nutrients often need to be supplemented through fertilizers for optimal crop yield, especially for nutrient-demanding crops like sugarcane. Their characteristic black colour is attributed to the presence of titanium salts and iron oxides.

9. Which one of the following is found in appreciable amount in Laterite

Which one of the following is found in appreciable amount in Laterite soil in India ?

Calcium

Phosphate

Potash

Nitrogen

This question was previously asked in

UPSC NDA-2 – 2024

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Laterite soils are formed under conditions of high temperature and heavy rainfall, which leads to intense leaching. This process removes soluble bases (like calcium, potassium, sodium, magnesium) and silica, leaving behind hydrated oxides of iron and aluminum. Therefore, laterite soils are typically deficient in nitrogen (due to low organic matter), potash (potassium), and calcium (lime).

While laterite soils are generally low in all the listed nutrients (Calcium, Phosphate, Potash, Nitrogen), total phosphorus content can sometimes be present in relatively appreciable amounts compared to the very low levels of nitrogen, potassium, and calcium, although a significant portion of this phosphorus is fixed by iron and aluminum oxides and is unavailable to plants. Assuming “appreciable amount” refers to total content rather than plant-available content or relative to other deficient elements, Phosphate is the most plausible option among the choices, despite the overall low fertility of laterite soils.

Laterite soils are rich in iron oxide (giving them a reddish colour) and aluminium oxide. They are often acidic. Due to the leaching process, they are generally poor in plant nutrients like nitrogen, phosphorus, potassium, and calcium. However, deposits of bauxite (aluminum ore) and iron ore are often found in laterite profiles.

10. Which one among the following statements with reference to the black c

Which one among the following statements with reference to the black cotton soils of India is NOT correct ?

The black cotton soils are also called 'Regur'

They are highly moisture retentive

They are rich in lime

These soils have less clay factor and hence can support a wide variety of crops and vegetables

This question was previously asked in

UPSC NDA-2 – 2024

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The statement “These soils have less clay factor and hence can support a wide variety of crops and vegetables” is NOT correct. Black cotton soils are characterized by a high clay content, which gives them their distinct properties.

– Black cotton soils, also known as Regur, are known for their high clay percentage (often >40-50%).
– The high clay content makes them highly moisture retentive.
– They are rich in minerals like lime, iron, magnesia, and alumina, but generally deficient in nitrogen, phosphorus, and organic matter.
– Due to the high clay content and moisture retention properties, they swell when wet and shrink/crack extensively when dry, making cultivation challenging, especially during the wet season.
– While suitable for crops like cotton, sugarcane, jowar, and groundnut, their characteristic properties limit the “wide variety of crops and vegetables” they can easily support compared to loamy soils.

The extensive cracking during the dry season helps in aeration, a process sometimes referred to as ‘self-ploughing’. These soils are predominantly found in the Deccan Trap region, covering parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and Tamil Nadu.