Q11. All of the following are typical chemical characteristics of the desert sandy soils of the Thar region, except:
Soils of Rajasthan: RAS Prelims MCQs
37 RAS Prelims MCQs on the soils of Rajasthan cover the soil types, their districts and properties. Desert sandy soils, alluvial soils of the eastern plains, black soils of Kota and Bundi, the Bhangar and Khadar deposits, the Entisols of USDA taxonomy and the problem of salinity are asked as facts and causes.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 11–20 of 37 questions
Q12. What is the primary cause for the widespread formation of calcic horizons (kankar pans) in the subsurface of western Rajasthan’s sandy soils?
Explanation
The formation of subsurface kankar pans or calcic horizons in western Rajasthan is primarily driven by the upward capillary movement of water. In this arid climate, groundwater containing dissolved calcium minerals moves toward the surface. As the water evaporates due to high temperatures, the minerals precipitate and accumulate at a certain depth, eventually hardening into a distinct and stony subsurface layer.
Q13. In which of the following sets of districts are alluvial soils most extensively found in Rajasthan?
Explanation
Alluvial soils are most extensively distributed across the eastern and north-eastern parts of Rajasthan, where river systems have deposited fertile sediments. Districts such as Bharatpur, Dholpur, and Tonk feature these productive soils. They are characterized by a fine to medium texture and are capable of supporting intensive agriculture, provided there is adequate irrigation and proper organic nutrient management.
Q14. In the context of the eastern plains of Rajasthan, the older alluvial soil deposits that are generally located above the present flood levels are known as:
Explanation
In the riverine plains of eastern Rajasthan, older alluvial deposits situated above the current flood levels are referred to as Bhangar. Unlike the newer, frequently replenished Khadar soils found in active floodplains, Bhangar soils are more stable and often contain calcareous concretions known as kankar. They are generally less fertile than Khadar but still support significant and productive agricultural activity.
Q15. Match the river basins of Rajasthan (List I) with the dominant soil types found within them (List II):
| River Basins | Dominant Soil Types |
|---|---|
| A. Luni Basin | i. Red Loam Soil |
| B. Mahi Basin | ii. Alluvial and Black Soil |
| C. Chambal Basin | iii. Brown Sandy Soil |
| D. Banas Basin | iv. Yellowish Brown Soil |
Explanation
Soil types in Rajasthan vary significantly across different river basins. The Luni basin is characterized by brown sandy soils, while the Mahi basin features red loam. The Chambal basin is dominated by a mix of alluvial and black soils due to its unique topography and parent material. The Banas basin is primarily associated with yellowish-brown soils throughout its entire geographic course.
Q16. Which of the following statements correctly describes the fertility profile of the alluvial soils in eastern Rajasthan?
Explanation
The alluvial soils found in eastern Rajasthan possess a distinct fertility profile. They are naturally rich in essential minerals like potash and lime, which are beneficial for plant growth.
Q17. Consider the following characteristics of soils:
I. Formed by fluvial deposition over thousands of years.
II. Capable of supporting intensive agriculture with proper irrigation.
III. Highly acidic in reaction with pH typically below 5.5.
Which combination is correct for the alluvial soils of eastern Rajasthan?
I. Formed by fluvial deposition over thousands of years.
II. Capable of supporting intensive agriculture with proper irrigation.
III. Highly acidic in reaction with pH typically below 5.5.
Which combination is correct for the alluvial soils of eastern Rajasthan?
Explanation
Alluvial soils in the eastern plains are formed through fluvial deposition over thousands of years, making them highly productive for agriculture. They respond well to intensive farming when supported by irrigation. Unlike acidic soils, these alluvial deposits are generally neutral to slightly alkaline in reaction, providing a favorable environment for the cultivation of a wide variety of food and commercial crops.
Q18. Identify the odd one out among the following districts based on the absence of significant alluvial soil cover:
Explanation
Among the listed districts, Jaisalmer is the odd one out regarding soil types. While Alwar, Dausa, and Sawai Madhopur are part of the eastern plains and feature significant alluvial soil cover deposited by rivers, Jaisalmer is located deep within the Thar Desert. Its landscape is dominated by desert sandy soils and shifting dunes rather than fluvial alluvial deposits.
Q19. Red and yellow soils in Rajasthan are predominantly concentrated in the districts of:
Explanation
Red and yellow soils are predominantly concentrated in the transitional zones of Rajasthan. These soils are most commonly found in districts such as Sawai Madhopur, Bhilwara, and Ajmer. Their distribution is linked to the weathering of crystalline and metamorphic rocks in regions receiving intermediate rainfall, where the hydration and oxidation states of iron minerals determine the soil’s distinct color.
Q20. Given below are two statements, one labelled as
Assertion (A) and the other labelled as Reason (R):
Assertion (A): Certain soils in the transitional plains of Sawai Madhopur and Bhilwara display a distinct yellow color.
Reason (R): Ferric oxides present in these soils undergo a process of hydration in regions of intermediate rainfall. In the context of the above statements, which one of the following is correct?
Assertion (A) and the other labelled as Reason (R):
Assertion (A): Certain soils in the transitional plains of Sawai Madhopur and Bhilwara display a distinct yellow color.
Reason (R): Ferric oxides present in these soils undergo a process of hydration in regions of intermediate rainfall. In the context of the above statements, which one of the following is correct?
Explanation
The distinct yellow color observed in the soils of Sawai Madhopur and Bhilwara is a result of chemical processes acting on iron minerals. When ferric oxides present in the soil undergo hydration under conditions of intermediate rainfall, they transition from red to yellow. This pedogenic process is common in regions where moisture levels are sufficient to cause hydration but not leaching.Answer key for these questions
| Q | Correct answer |
|---|---|
| 11 | (b) Elevated levels of available nitrogen |
| 12 | (d) Evaporation leading to upward capillary movement of calcium solutions |
| 13 | (a) Bharatpur, Dholpur, and Tonk |
| 14 | (b) Bhangar |
| 15 | (a) A-iii, B-i, C-ii, D-iv |
| 16 | (a) Rich in potash and lime but deficient in nitrogen and phosphorus |
| 17 | (a) I and II only |
| 18 | (c) Jaisalmer |
| 19 | (b) Sawai Madhopur, Bhilwara, and Ajmer |
| 20 | (a) Both A and R are true and R is the correct explanation of A. |
Key facts from Soils of Rajasthan
- In the arid west, extreme climate is the dominant factor in soil formation.
- Alluvial soils are most extensive in Bharatpur, Dholpur and Tonk; older alluvium is called Bhangar.
- Desert sandy soils have sandy and loamy sand textures with weak profile development.
- Black soils of Kota and Bundi shrink and swell because of the mineral montmorillonite; deep black soil is found in Jhalawar.
- Entisols occupy the largest area under the USDA soil taxonomy.
- Salts rise to the surface by capillary action and cause salinity.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Soils of Rajasthan?
This page has 37 practice MCQs on Soils of Rajasthan (Rajasthan Geography). Each has the correct answer, and most have an explanation.
Which soil occupies the largest area in Rajasthan?
The Entisols, according to the USDA soil taxonomy. They are young soils with little profile development, typical of sandy desert areas, and they cover the arid west of the State from Jaisalmer and Barmer to Bikaner.
Why do black soils crack and swell?
Because they contain the clay mineral montmorillonite, which expands when wet and shrinks when dry. This gives the black soils of Kota and Bundi their deep cracks in summer.
What is Bhangar?
The older alluvial deposits of the eastern plains, found on higher terraces above the flood level. The newer flood-plain deposits are called Khadar, and the two are used to describe the alluvial plains of north India.