All questions of Soils for UPSC CSE Exam

• Alkali, or alkaline, soils are clay soils with high pH (> 8.5), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1-metre depth.
• Alkali soils owe their unfavourable physicochemical properties mainly to the dominating presence of sodium carbonate which causes the soil to swell and difficult to clarify/settle.

Black soil rich in iron oxide, alumina but very low in humus, phosphates and nitrogen. Also named as regur and best soil for cotton cultivation.

Black Soil of India

Statement 1: Black soil becomes sticky when it is wet.
Yes, this statement is correct. Black soil, also known as regur soil or black cotton soil, is a type of soil that is found in India. It is known for its high fertility and moisture-retaining capacity. When the soil gets wet, it becomes sticky and compact due to its high clay content. This stickiness can make it difficult for water to drain properly, leading to waterlogging in some areas.

Statement 2: Black soil contains adequate nitrogen as well as phosphorus required for the growth of plants.
This statement is incorrect. While black soil is rich in certain nutrients like calcium, magnesium, and potassium, it generally lacks in nitrogen and phosphorus. Nitrogen and phosphorus are crucial elements for plant growth and development. However, black soil is deficient in these nutrients, which means that additional fertilizers need to be added to enhance the soil's fertility and provide the necessary nitrogen and phosphorus for plants.

Conclusion:
In conclusion, statement 1 is correct as black soil does become sticky when wet. However, statement 2 is incorrect as black soil generally lacks adequate nitrogen and phosphorus for plant growth. Therefore, the correct answer is option 'A' - Only 1.

The alluvial soil found along the banks of the rivers in the Ganga plain is called Khadar. This type of soil is formed due to the deposition of silt and other fine particles by the rivers during flood events. It is one of the most fertile soils in India and is widely used for agricultural purposes.

Here is a detailed explanation of why the correct answer is option 'A' - Khadar:

Formation of Khadar Soil:
- The Ganga plain is characterized by its vast alluvial deposits, which are mainly composed of silt, sand, clay, and other organic matter brought by the rivers.
- When the rivers like Ganga, Yamuna, and their tributaries overflow during the monsoon season, they carry large amounts of sediments and deposit them on the banks.
- These sediments settle down as the floodwaters recede, forming a layer of fertile soil along the riverbanks. This soil is known as Khadar.

Characteristics of Khadar Soil:
- Khadar soil is very fertile due to the presence of fine particles and organic matter in it.
- It has a higher proportion of clay and silt, which gives it good water retention capacity.
- The soil is well-drained and has a high nutrient content, making it suitable for the cultivation of various crops.
- Khadar soil is generally dark in color, indicating its high fertility.

Usage of Khadar Soil:
- Due to its fertility, Khadar soil is extensively used for agriculture in the Ganga plain.
- It is suitable for the cultivation of crops like rice, wheat, sugarcane, vegetables, and pulses.
- The soil's ability to retain water helps in sustaining the crops during dry periods.
- Farmers in the region rely on Khadar soil for their livelihoods as it supports high agricultural productivity.

Comparison with Other Alluvial Soils:
- Bhangar soil is another type of alluvial soil found in the Ganga plain, but it differs from Khadar soil in terms of its formation and characteristics.
- Bhangar soil is older and less fertile compared to Khadar soil. It is formed from older alluvial deposits and is found at a higher elevation.
- Bhur soil, on the other hand, is a sandy soil with low fertility and poor water retention capacity.
- Loess soil is a wind-blown sedimentary soil found in some regions, but it is not found along the banks of rivers in the Ganga plain.

Overall, Khadar soil is the correct answer as it accurately describes the alluvial soil found along the banks of the rivers in the Ganga plain. Its fertility, water retention capacity, and nutrient content make it highly suitable for agriculture in the region.

Black Soil - Regur
Black soil, also known as Regur, is a type of soil that is commonly found in the Deccan Plateau region of India. Here are some key points about black soil:

Characteristics:
- Black soil is rich in minerals like calcium, magnesium, and iron, making it highly fertile.
- It has a high clay content, which gives it good moisture retention properties.
- The soil is dark in color due to its high organic matter content.

Origin:
- Black soil is formed from the weathering of basalt rocks, which are rich in iron, magnesium, and calcium.
- The soil gets its black color from the presence of non-soluble compounds of iron and aluminum.

Distribution:
- Black soil is primarily found in the Deccan Plateau region of India, covering states like Maharashtra, Madhya Pradesh, and parts of Gujarat, Andhra Pradesh, and Telangana.
- It is also found in some parts of other countries like Sri Lanka and parts of Africa.

Usage:
- Black soil is highly suitable for cultivation of crops like cotton, sugarcane, pulses, and oilseeds.
- It is known for its ability to retain moisture during dry periods, making it ideal for crops that require water.
In conclusion, black soil, or Regur, is a type of soil that is characterized by its high fertility, dark color, and rich mineral content. It plays a crucial role in agriculture in the Deccan Plateau region and is highly valued for its agricultural productivity.

• Laterite soil is rich in aluminium and iron, formed in wet and hot tropical areas. Almost all laterite soils are red due to the presence of iron oxides. It is prepared by the prolonged and rigorous weathering of the parent rock.

• Laterite soil is characterized by the possession of iron oxides with red colour. Nitrogen, Phosphorus and potash are not present in proper quantities so it shows low fertile texture.
• Tapioca and cashew nuts are generally grown in such soil. This soil is found loss or more in states- Odisha, Maharashtra, Andhra, Tamil Nadu, Karnataka, Meghalaya and West Bengal.

Mulching: An Agronomic Measure of Soil Conservation

Mulching is an agronomic practice that involves covering the soil surface with a layer of organic or inorganic material. It is widely recognized as an effective method of soil conservation due to its numerous benefits. Let's explore why mulching is considered to be highly effective:

1. Protects Soil from Gully Erosion:
Gully erosion is the process by which water accumulates and flows in narrow channels, causing deep and extensive erosion. Mulching plays a crucial role in preventing gully erosion by reducing the impact of rainfall on the soil surface. When rainwater hits the mulch layer, it is dispersed evenly, reducing the chances of concentrated flow and subsequent erosion. The mulch acts as a buffer, absorbing and dissipating the energy of raindrops, thereby protecting the soil from being washed away in gullies.

2. Protects Soil from Sheet Wash and Wind Erosion:
Sheet wash erosion occurs when water flows over the soil surface in a thin layer, carrying away soil particles. Wind erosion, on the other hand, involves the transport of soil particles by the force of wind. Mulching effectively combats both sheet wash and wind erosion. The layer of mulch acts as a physical barrier, preventing the direct impact of raindrops and wind on the soil surface. This protects the soil from being eroded and ensures its stability and integrity.

3. Helps Soil Retain Moisture and Nutrients:
Mulching significantly improves the soil's ability to retain moisture and nutrients. The mulch layer acts as a protective covering, reducing evaporation and preventing excessive water loss. This helps to maintain soil moisture levels, particularly in arid and semi-arid regions. Additionally, the mulch decomposes over time, enriching the soil with organic matter and essential nutrients. This enhances soil fertility and nutrient availability for plant growth, leading to improved crop yields.

In Conclusion:
Mulching is an effective agronomic measure of soil conservation due to its ability to protect the soil from gully erosion, sheet wash, and wind erosion. It also helps to retain moisture and nutrients in the soil, promoting healthier plant growth. By implementing mulching practices, farmers and land managers can mitigate soil erosion, improve soil quality, and enhance agricultural productivity.

• Red soils develop in a warm, temperate, wet climate under deciduous forests and have thin organic and mineral layers overlying a yellowish-brown leached layer resting on a red layer made of iron oxide(ferric oxide).
• Red soils generally form from iron-rich sediments. They are usually poor growing soils, low in nutrients and humus and difficult to cultivate.

Red Soils of India

• Red soils are one of the most important types of soils found in India. They cover about 10.6% of the total land area of the country.

• The colour of the soil is red due to the presence of ferric oxide content.

• Red soils are generally acidic in nature and have a pH range of 5-6.5.

• They are found in areas with low rainfall and high temperature, such as the Deccan Plateau, parts of Tamil Nadu, Karnataka, Andhra Pradesh, and Maharashtra.

Characteristics of Red Soils

1. Colour: The colour of the soil is red due to the presence of ferric oxide content.

2. Texture: Red soils are generally sandy in texture, but they can also be loamy and clayey.

3. Porosity: Red soils are porous and have a friable structure. This means that they are easy to cultivate and have good drainage.

4. Nutrient content: Red soils are deficient in nitrogen, phosphorus, and organic matter. However, they are rich in iron, aluminium, and magnesium.

5. Water-holding capacity: Red soils have low water-holding capacity, which makes them unsuitable for crops that require a lot of water.

6. Fertility: Red soils are generally poor in fertility, but they can be made fertile by adding organic matter and fertilizers.

Conclusion

The correct option is (b) 1 and 3. Red soils of India are characterized by their red colour due to high ferric oxide content, porous and friable structure, and low water-holding capacity. They are deficient in nitrogen, phosphorus, and organic matter but rich in iron, aluminium, and magnesium. Red soils are generally found in areas with low rainfall and high temperature.

Karewas in Jhelum Valley
Karewas are glacial terraces found in the Jhelum Valley of India. Let's explore this answer in detail.

What are Karewas?
- Karewas are a type of landform that are formed due to the deposition of glacial sediments in a valley.
- They are typically composed of clay, silt, sand, and gravel that have been transported and deposited by glaciers during the Pleistocene era.
- These glacial sediments accumulate over time and form terraces, creating a distinct landscape.

Jhelum Valley
- The Jhelum Valley is located in the state of Jammu and Kashmir in northern India.
- It is a major valley in the western Himalayas and is traversed by the Jhelum River, which is a tributary of the Indus River.
- The valley is surrounded by towering mountains and is known for its scenic beauty.

Karewas in Jhelum Valley
- The Jhelum Valley is home to several Karewas, which are prominent features of the region.
- These Karewas are characterized by their flat or gently sloping terraces that rise above the surrounding landscape.
- They are typically covered with fertile soil and support agricultural activities in the region.
- The Karewas in the Jhelum Valley are believed to have been formed during the Pleistocene era when glaciers were more extensive in the region.
- Over time, the glaciers retreated, leaving behind these terraces formed by the deposition of glacial sediments.

Importance of Karewas
- Karewas are important from both a geological and ecological perspective.
- They provide valuable insights into the past climate and environmental changes that have occurred in the region.
- The fertile soil of the Karewas supports agriculture, making them significant for the local economy.
- Additionally, Karewas often contain deposits of valuable minerals and resources, which can be economically beneficial.

Conclusion
In conclusion, glacial terraces known as Karewas are found in the Jhelum Valley of India. These terraces are formed by the deposition of glacial sediments during the Pleistocene era. The Karewas in the Jhelum Valley are not only visually appealing but also have significant geological, ecological, and economic importance.

Answer :

• b)
  capillary water

 Capillary water

The alluvial soil is spread all over the plains of north India.

Laterite soil - Punjab because laterite soil found in hilly area where high humidity and temp conditions which are favourable for tea cultivation