51 practice questions on Soils from the Geography section of the UPSC Prelims syllabus.
51 come with a written explanation and 8 are actual previous year questions.
Try the sample set below - the answer stays hidden until you ask for it.
12 Easy28 Medium11 Hard8 from past papers
Sample questions
Q1
Previous year questionmedium
Consider the following statements:
Statement-I: The soil in tropical rain forests is rich in nutrients.
Statement-II: The high temperature and moisture of tropical rain forests cause dead organic matter in the soil to decompose quickly.
Which one of the following is correct in respect of the above statements?
ABoth Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
BBoth Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
CStatement-I is correct but Statement-II is incorrect
DStatement-I is incorrect but Statement-II is correct
Show answer and explanation
Correct answer: D - Statement-I is incorrect but Statement-II is correct
The correct choice is (d). Tropical rainforest soils are actually nutrient-poor because heavy rainfall leaches minerals and most nutrients are held in the living biomass, so Statement-I is wrong. Statement-II is true, since the hot, humid conditions speed up decomposition and nutrients are rapidly taken up by plants rather than stored in the soil. Because only Statement-II is correct, options claiming both are correct or that Statement-I alone is correct are eliminated.
Q2
Previous year questionmedium
Contour bunding is a method of soil conservation used in
Adesert margins, liable to strong wind action
Blow flat plains, close to stream courses, liable to flooding
Cscrublands, liable to spread of weed growth
DNone of the above
Show answer and explanation
Correct answer: D - None of the above
Contour bunding involves building earthen embankments along the contour lines of sloping or undulating land to check the velocity of runoff and reduce soil erosion by water. None of the three given settings (wind-prone desert margins, flat flood-prone plains, or weed-infested scrublands) describes this; the technique is meant for sloping terrain. Hence option (d), None of the above, is correct.
Q3
Previous year questionmedium
The black cotton soil of India has been formed due to the weathering of
Abrown forest soil
Bfissure volcanic rock
Cgranite and schist
Dshale and limestone
Show answer and explanation
Correct answer: B - fissure volcanic rock
Black cotton soil, or regur, of the Deccan has developed from the weathering of basaltic lava poured out as fissure volcanic eruptions that built the Deccan Traps, so the correct answer is fissure volcanic rock. It is not derived from brown forest soils of the hills, and although granite, schist, shale and limestone weather into other soil types such as red and laterite soils, they do not produce the clay-rich, moisture-retentive black soil, so the remaining options are wrong.
Q4
Previous year questionmedium
With reference to agricultural soils, consider the following statements :
1. A high content of organic matter in soil drastically reduces its water holding capacity.
2. Soil does not play any role in the sulphur cycle.
3. Irrigation over a period of time can contribute to the salinization of some agricultural lands.
Which of the statements given above is/are correct ?
A1 and 2 only
B3 only
C1 and 3 only
D1, 2 and 3
Show answer and explanation
Correct answer: B - 3 only
High organic matter actually increases a soil's water holding capacity rather than drastically reducing it, so statement 1 is wrong; soil is an active part of the sulphur cycle through microbial transformations, so statement 2 is wrong; prolonged irrigation can indeed cause salinization through accumulation of salts, so statement 3 is correct. Therefore only statement 3 holds and the answer is (b) 3 only. The first two are common misconceptions about soil function.
Q5
Previous year questionmedium
Salinization occurs when the irrigation water accumulated in the soil evaporates, leaving behind salts and minerals. What are the effects of salinization on the irrigated land?
AIt greatly increases the crop production
BIt makes some soils impermeable
CIt raises the water table
DIt fills the air spaces in the soil with water
Show answer and explanation
Correct answer: B - It makes some soils impermeable
Correct answer (b) It makes some soils impermeable. When irrigation water evaporates it leaves behind salts that accumulate in the topsoil; high sodium content in particular degrades soil structure and seals pores, reducing permeability and harming crops. (a) is wrong because salinization lowers, not increases, crop production. (c) is the cause associated with waterlogging rather than an effect of salinization, and salinization itself does not raise the water table. (d) describes waterlogging, where pore spaces fill with water, which is a different problem.
Q6
Previous year questionmedium
Which of the following statements regarding laterite soils of India are correct?
1. They are generally red in colour.
2. They are rich in nitrogen and potash.
3. They are well-developed in Rajasthan and UP.
4. Tapioca and cashew nuts grow well on these soils.
Select the correct answer using the codes given below.
A1, 2 and 3
B2, 3 and 4
C1 and 4
D2 and 3 only
Show answer and explanation
Correct answer: C - 1 and 4
Laterite soils are generally reddish in colour due to iron oxides (statement 1) and support plantation crops such as tapioca and cashew nuts (statement 4), so option (c) is correct. Statement 2 is wrong because laterites are poor in nitrogen, phosphate, potash and humus owing to intense leaching in heavy rainfall areas. Statement 3 is incorrect because laterites develop in high-rainfall regions of the Western Ghats, eastern Ghats, Odisha and the northeast, not in the arid plains of Rajasthan and the Gangetic UP, which eliminates options (a), (b) and (d).
Q7
Previous year questionmedium
In India, the problem of soil erosion is associated with which of the following? 1. Terrace cultivation 2. Deforestation 3. Tropical climate Select the correct answer using the code given below.
A1 and 2 only
B2 only
C1 and 3 only
D1, 2 and 3
Show answer and explanation
Correct answer: B - 2 only
Per the official UPSC key the answer is 2 only. Deforestation (2) exposes soil and is a major driver of erosion. Terrace cultivation (1) is in fact a soil-conservation technique that slows runoff on slopes, so it is not associated with the problem of erosion. Tropical climate (3) by itself is a natural condition rather than the cause; erosion results from land mismanagement within it. Hence 2 only.
Q8
Previous year questionmedium
"Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees." This is the most likely description of
Aconiferous forest
Bdry deciduous forest
Cmangrove forest
Dtropical rain forest
Show answer and explanation
Correct answer: D - tropical rain forest
Rapid leaf-litter decomposition due to constant heat and humidity, a nearly bare soil surface, and an abundance of lianas (climbers) and epiphytes rooted high on branches are classic features of the tropical rain forest, so that is the correct answer. Coniferous forests of cold regions have slow decomposition and thick litter, dry deciduous forests shed leaves seasonally and lack this dense epiphyte cover, and mangroves are salt-tolerant coastal communities with stilt roots rather than canopy climbers, so none of them fits the description.
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