A conservation problem equally as important as that of soil erosion is the loss of soil fertility. Most agriculture was originally supported by the natural fertility of the soil; and, in areas in which soils were deep and rich in minerals, farming could be carried on for many years without the return of any nutrients to the soil other than those supplied through the natural breakdown of plant and animal wastes. In river basins, such as that of the Nile, annual flooding deposited a rich layer of silt over the soil, thus restoring its fertility. In areas of active volcanism, such as Hawaii, soil fertility has been renewed by the periodic deposition of volcanic ash. In other areas, however, natural fertility has been quickly exhausted. This is true of most forest soils, particularly those in the humid tropics. Because continued cropping in such areas caused a rapid decline in fertility and therefore in crop yields, fertility could be restored only by abandoning the areas and allowing the natural forest vegetation to return. Over a period if time, the soil surface would be rejuvenated by parent materials, new circulation channels would form deep in the soil, and the deposition of forest debris would restore minerals to the topsoil. Primitive agriculture in such forests was of shifting nature: areas were cleared of trees and the woody material burned to add ash to the soil; after a few years of farming, the plots would be abandoned and new sites cleared. As long as populations were sparse in relation to the area of forestland, such agricultural methods did little harm. They could not, however, support dense populations or produce large quantities of surplus foods.
Starting with the most easily depleted soils, which were also the easiest to farm, the practice of using various fertilizers was developed. The earliest fertilizers were organic manures, but later, larger yields were obtained by adding balanced combinations of those nutrients (e.g. potassium, nitrogen, phosphorus and calcium) that crop plants require in greatest quantity. Because high yields are essential, most modern agriculture depends upon the continued addition of chemical fertilizers to the soil. Usually these substances are added in mineral form, but nitrogen is often added as urea, an organic compound.
Early in agricultural history, it was found that the practice of growing the same crop year after year in a particular plot of ground not only caused undesirable changes in the physical structure of the soil, but also drained the soil of its nutrients. The practice of crop rotation was discovered to be a useful way to maintain the condition of the soil, and also to prevent the buildup of those insects and other plant pests that are attracted to a particular kind of crop. In rotation systems, a grain crop is often grown the first year, followed by a leafy vegetable crop in the second year, and pasture crop in the third. The last usually contains legumes (e.g. clover, alfalfa), because such plants can restore nitrogen to the soil through the action of bacteria that live in nodules on their roots.
In irrigation agriculture, in which water is brought in to supply the needs of crops in an area with insufficient rainfall, a particular soil-management problem that develops is the salinization (concentration of salts) of the surface soil. This most commonly results from inadequate drainage of the irrigated land; because the water cannot flow freely, it evaporates, and the salts dissolved in the water are left on the surface of the soil. Even though the water does not contain a large concentration of dissolved salts, the accumulation over the years can be significant enough to make the soil unsuitable for crop production. Effective drainage solves the problem; in many cases, drainage canals must be constructed, and drainage tiles must be laid beneath the surface of the soil. Drainage also requires the availability of an excess of water to flush the salts from the surface soil. In certain heavy soils with poor drainage, this problem can be quite severe; for example, large areas of formerly irrigated land in the Indus basin, in the Tigris Euphrates region, in the Nile Basin, and in the Western United States, have been seriously damaged by salinization.
The areas most prone to salinization are
Show Hint
- those irrigated with well-water.
- those in which crop rotation is not practiced.
- sub-tropical forests.
- flat land irrigated from reservoirs.
The Correct Option is D
Solution and Explanation
Step 2: It highlights severe cases in flat lands like the Indus, Tigris-Euphrates, Nile basins, and the Western U.S., often irrigated from reservoirs.
Step 3: Option D (flat land irrigated from reservoirs) matches the passage’s description of areas prone to salinization due to poor drainage.
Step 4: Option A (well-water) is not mentioned as a specific cause of salinization.
Step 5: Option B (no crop rotation) is unrelated to salinization in the passage.
Step 6: Option C (sub-tropical forests) refers to areas with exhausted fertility, not salinization.
Verification: Flat lands with reservoir irrigation align with the passage’s examples of salinization-prone areas.
The most appropriate title to this passage is
Show Hint
- Problems of soil erosion
- Agriculture in Volcanic islands
- The importance of chemical fertilizers
- Causes of and remedies of soil-infertility
The Correct Option is D
Solution and Explanation
Step 2: It explains causes like natural fertility exhaustion (e.g., in humid tropical forests) and salinization in irrigated lands.
Step 3: It also describes remedies like crop rotation, organic manures, chemical fertilizers, and drainage systems to restore fertility.
Step 4: Option D (Causes of and remedies of soil-infertility) captures both the causes (exhaustion, salinization) and remedies (fertilizers, drainage) discussed.
Step 5: Option A (soil erosion) is mentioned but not the main focus.
Step 6: Option B (volcanic islands) is a minor example, not the central theme.
Step 7: Option C (chemical fertilizers) covers only one remedy, not the full scope.
Verification: Option D best summarizes the passage’s focus on soil infertility’s causes and solutions.
Natural fertility exhausts most quickly in
Show Hint
- river valley lands
- humid tropical forests
- volcanic areas
- lands near urban areas
The Correct Option is B
Solution and Explanation
Step 2: It explains that continued cropping in these areas leads to rapid fertility decline, requiring abandonment for natural restoration.
Step 3: Option B (humid tropical forests) directly matches the passage’s emphasis on rapid fertility exhaustion in these regions.
Step 4: Option A (river valley lands) is incorrect as the passage cites the Nile’s annual flooding as restoring fertility.
Step 5: Option C (volcanic areas) is wrong because volcanic ash renews fertility, as seen in Hawaii.
Step 6: Option D (lands near urban areas) is not mentioned in the passage.
Verification: Humid tropical forests are explicitly identified as losing fertility fastest.
The factor that can restore fertility to the soil not mentioned in the passage is
Show Hint
- alluvium brought by rivers
- bacterial action
- fertilizer fixation through lightning
- organic manure
The Correct Option is C
Solution and Explanation
Step 2: Option A (alluvium) is mentioned (e.g., Nile’s silt deposits).
Step 3: Option B (bacterial action) is implied in the natural breakdown of wastes, which involves bacteria.
Step 4: Option D (organic manure) is explicitly mentioned as an early fertilizer.
Step 5: Option C (fertilizer fixation through lightning) is not mentioned anywhere in the passage.
Step 6: Lightning can fix nitrogen in the soil, but the passage does not reference this process.
Verification: Option C is the only factor not discussed in the passage.
Crop rotation helps to
I. increase the farmer’s seasonal income.
II. preserve soil condition.
III. desalinize the soil.
IV. destroy pests.
Show Hint
- I, II, III & IV
- I, II & IV only
- II & IV only
- II, III & IV only
The Correct Option is C
Solution and Explanation
Step 2: Generally, crop rotation is known to preserve soil condition (II) by maintaining nutrient balance and to destroy pests (IV) by disrupting their life cycles.
Step 3: Desalinization (III) is addressed in the passage through drainage and flushing, not crop rotation.
Step 4: Increasing seasonal income (I) is not a direct benefit of crop rotation mentioned in the passage or generally associated with it.
Step 5: Thus, only II (preserve soil condition) and IV (destroy pests) are correct.
Step 6: Option C (II & IV only) matches these benefits.
Verification: Options including I or III are incorrect based on the passage and standard agricultural knowledge.
One of the characteristics of agricultural land in Nile basin is
Show Hint
- it contains a lot of bacteria.
- it consists of heavy soil with poor drainage properties.
- the Nile water contains an excess of salts.
- it contains nutritive minerals.
The Correct Option is B
Solution and Explanation
Step 2: Option B (heavy soil with poor drainage) directly matches this description.
Step 3: Option A (bacteria) is not mentioned as a characteristic of Nile basin soil.
Step 4: Option C (excess salts in Nile water) is incorrect; the passage implies salts accumulate from irrigation, not that Nile water inherently contains excess salts.
Step 5: Option D (nutritive minerals) is true due to silt deposits, but the question asks for a characteristic linked to salinization, making B more specific.
Verification: The passage explicitly links the Nile basin to heavy soils with poor drainage causing salinization.
Top Questions on Reading Comprehension
- Read the following passage and answer the question that follows. \textit{Passage:} The lovely thing about the unsayable is that it is unsaid. As soon as it is said, it is sayable and loses all its mystery and ambiguity. Art exists so that the unsayable can be said without having to actually say it. We cloud it in secrecy and obfuscation. The mind is free to roam and all things can be imagined, under the cover of darkness. How nice that is. The unsayable. How tired we are of having things explained to us. Having things said. How nice it is when people just shut ... up. Which of the following options can be BEST inferred from the passage?
- XAT - 2025
- Verbal and Logical Ability
- Reading Comprehension
Trade is essentially the buying and selling of items produced elsewhere. All the services in retail and wholesale trading or commerce are specifically intended for profit. The towns and cities where all these works take place are known as trading centres. The rise of trading from barter at the local level to money-exchange on an international scale has produced many centres and institutions, such as trading centres or collection and distribution points.
Trading centres may be divided into rural and urban marketing centres. Rural marketing centres cater to nearby settlements. These are quasi-urban centres. They serve as trading centres of the most rudimentary type. Here, personal and professional services are not well-developed. These form local collecting and distributing centres. Most of these have mandis (wholesale markets) and also retailing areas. They are not urban centres per se but are significant centres for making available goods and services which are most frequently demanded by rural folk.
Periodic markets in rural areas are found where there are no regular markets and local periodic markets are organised at different temporal intervals. These may be weekly, bi-weekly markets where people from the surrounding areas meet their temporally accumulated demand. These markets are held on specified dates and move from one place to another. The shopkeepers, thus, remain busy all day while a large area is served by them.
Urban marketing centres have more widely specialised urban services. They provide ordinary goods and services as well as many of the specialised goods and services required by people. Ur- ban centres, therefore, offer manufactured goods as well as many specialised developed markets, e.g. markets for labour, housing, semi-or finished products. Services of educational institutions and professionals such as teachers, lawyers, consultants, physicians, dentists and veterinary doctors are available.- CUET (UG) - 2025
- Geography
- Reading Comprehension
- India even now possesses a wealth of manuscripts running into many millions. Tradi- tionally, they were written on materials such as birch bark (bh¯urja pattra) and palm leaves. Birch bark was mainly used for north Indian scripts, and the writing was done with ink made of finely ground charcoal powder in a medium of gum, or soot from oil lamps. With palm leaves, there was no ink; rather, a sharp point was used to tear the leaf’s surface film; it would then be smeared with a paste of charcoal powder mixed in oil.
The art of paper making was introduced into India by the 11th century CE, perhaps from China through Nepal. The earliest extant Indian paper manuscript is dateable to 1105 CE; it was made from the fibers of a mountain plant. By the later half of the 15th century, Kashmir was producing paper of attractive quality from the pulps of rags and hemp, with lime and soda added to whiten the pulp. Sialkot, Zafarabad, Patna, Murshidabad, Ahmedabad, Aurangabad and Mysore were among the well- known centers of paper production.- CUET (UG) - 2025
- Knowledge Tradition - Practices India
- Reading Comprehension
- The arena is also described in the Mallapurāṇa. It is not the mat as is used to-day. The arena is known as ākhādhaka. It is high, levelled and low. Its dimensions are three devamāna (101 hastas or cubits), daityamāna (50 hastas) and martyamāna (21 hastas). It is square, triangular and circular. The earth with kankar, iron, wood, stone, thorn etc. should be avoided. It appears that the general dimension was 21 hastas which is equal to about 30 feet, and the devamāna and daityamāna seem to be more for rhetorics rather than actual use. The earth must be pleasing to see and as soft as that required for seed-laying and should be a hand high and levelled. It should be worshipped and Hari should be placed there and a bījapūraka be placed in the center of the arena. After worshiping 'Govinda' the king should see the wrestling.
- CUET (UG) - 2025
- Knowledge Tradition - Practices India
- Reading Comprehension
- In the counselling process, the professional counsellor may use different techniques. In directive or counsellor-centred counselling, the counsellor plays a major role and does all that is possible to get the counsellee to make decisions in keeping with the diagnosis of the problem. In non-directive or permissive or client-centred counselling, the counsellor’s role is comparatively passive. The counsellee takes an active part in the process of therapy. The person seeking help is encouraged to gain insight into the problem with the help of the counsellor. The counsellee takes the final decisions. Thus, this counselling process turns out to be a growth experience for the person. In eclectic counselling, counsellors who advocate using this type of counselling are of the view that directed or non-directed counselling are two ends of continuum. And counsellors should incorporate suitable techniques from both the types of counselling mentioned above as and when required, depending on the situation, the problem and the temperament of the client.
- CUET (UG) - 2025
- Home Science
- Reading Comprehension
Questions Asked in CAT exam
- The sum of all real values of $k$ for which $(\frac{1}{8})^k \times (\frac{1}{32768})^{\frac{4}{3}} = \frac{1}{8} \times (\frac{1}{32768})^{\frac{k}{3}}$ is
- CAT - 2024
- Logarithms
When $10^{100}$ is divided by 7, the remainder is ?
- CAT - 2024
- Basics of Numbers
- If $(a + b\sqrt{n})$ is the positive square root of $(29 - 12\sqrt{5})$, where $a$ and $b$ are integers, and $n$ is a natural number, then the maximum possible value of $(a + b + n)$ is ?
- CAT - 2024
- Algebra
- A regular octagon ABCDEFGH has sides of length 6 cm each. Then the area, in sq. cm, of the square ACEG is
- CAT - 2024
- Mensuration
- Let $x$, $y$, and $z$ be real numbers satisfying
\(4(x^2 + y^2 + z^2) = a,\)
\(4(x - y - z) = 3 + a.\)
Then $a$ equals ?- CAT - 2024
- Algebra