Soil

Select the type of soil that is best suited for growing wheat.

• Loamy soil

• Red soil

• Sandy soil

• Peaty soil

Answer explanation

Loamy soil is ideal for growing wheat as it retains moisture and provides good aeration.

The process by which soil is transported by wind, water, or ice is called ______.

Answer explanation

Erosion is the process by which soil and rock are removed from the Earth's surface.

Explain the role of climate in soil formation.

Answer explanation

Climate affects soil formation through temperature and rainfall, which influence weathering of the parent rock and the decomposition of organic matter.

Areas with steep slopes will experience (a)   amounts of soil erosion, resulting in a ​ (b)   layer of topsoil. Flat areas at the base of slopes will experience ​ (c)   amounts of soil deposition, resulting in a ​ (d)   layer of topsoil.

• high
• thin or missing
• low
• thick and rich

Answer explanation

Steep slopes experience high soil erosion due to fast water flow and gravity, removing topsoil. In contrast, flat areas at the base of slopes have slower water flow, leading to soil deposition and the formation of a thick, rich layer of topsoil.

Label the different soil layers in the diagram.

a

b

c

d

e

Bed Rock

Sub soil

Humus

Top soil

Parent material

Answer explanation

A soil profile consists of layers called horizons, arranged from top to bottom:

1. O Horizon: Organic/Humus layer, rich in decomposed leaves and organic matter.

2. A Horizon (Topsoil): Dark, nutrient-rich layer where plants grow; contains organic material mixed with minerals.

3. B Horizon (Subsoil): Accumulation of minerals like iron and clay leached from above; less organic material.

4. C Horizon: Weathered parent material, partially broken down rock.

5. R Horizon: Bedrock, the unweathered solid rock beneath all other layers.

These layers reflect the formation and composition of soil over time.

Match the following soil type along with their region.

• Mountainous/forest soil

• 
• Black soil

• 
• Alluvial soil

• 
• Arid soil

• 

Answer explanation

1. Black Soil (Regur Soil):

   • Found in the Deccan Plateau, covering states like Maharashtra, Madhya Pradesh, Gujarat, Karnataka, and parts of Andhra Pradesh.

   • Ideal for growing cotton, hence also called "cotton soil."

2. Alluvial Soil:

   • Found in the Northern Plains, covering the states of Punjab, Haryana, Uttar Pradesh, Bihar, West Bengal, and parts of Rajasthan, Assam, and the Gangetic Plain.

   • Rich and fertile, suitable for a variety of crops like rice, wheat, and sugarcane.

3. Arid Soil:

   • Found in the Thar Desert region of Rajasthan, parts of Gujarat, Punjab, and Haryana.

   • Dry and sandy, requiring irrigation for agriculture.

   • Mountainous/Forest Soil:

     • Found in the Himalayan region, Northeast India (Arunachal Pradesh, Sikkim, Assam), and parts of the Western Ghats.

How does time contribute to soil formation?

Answer explanation

Time contributes to soil formation by allowing physical, chemical, and biological processes to act on the parent material over long periods. These processes gradually break down rocks, add organic matter, and develop distinct soil layers or horizons. The longer the time, the more developed and mature the soil becomes, with well-defined characteristics and fertility.

Prepare a flow chart of factors affecting soil formation.

Answer explanation

The factors affecting soil formation are:

1. Parent Material: The type of rock from which soil originates influences its texture, mineral content, and fertility.

2. Climate: Temperature and rainfall affect the rate of weathering and organic matter decomposition.

3. Organisms: Plants, animals, and microorganisms contribute to the formation of humus and influence soil structure.

4. Topography: Slope and elevation affect drainage, erosion, and soil depth.

5. Time: Longer periods allow for more extensive weathering and development of soil layers.

Organize these options into the right categories

Groups:

(a) Physical weathering

,

(b) Chemical weathering

,

(c) Abiotic components

,

(d) Biotic components

• Freeze-thaw action, Exfoliation

• • Oxidation, Hydrolysis, Carbonation

  • Oxidation, Hydrolysis, Carbonation

• Microorganisms, Vegetation

• Temperature, Rainfall, Parent Rock

Answer explanation

• Physical Weathering:

  • Freeze-thaw action: Water freezes in cracks, breaking rocks.

  • Exfoliation: Rocks peel off due to temperature changes.

• Chemical Weathering:

  • Oxidation: Oxygen reacts with minerals.

  • Hydrolysis: Water breaks down minerals.

  • Carbonation: Carbonic acid dissolves rocks.

• Abiotic Components:

  • Temperature: Affects weathering rate.

  • Rainfall: Influences soil moisture and erosion.

  • Parent Rock: Determines soil composition.

• Biotic Components:

  • Microorganisms: Decompose organic matter.

  • Vegetation: Adds organic matter and prevents erosion.

Which of these do you think is the best solution to prevent soil erosion in mountainous regions?

• • Planting more vegetation

• • Building terraces

• • Using artificial barriers

• • Not sure

Answer explanation

1. Planting more vegetation: Roots of plants help bind the soil, preventing erosion by holding the soil together. Vegetation also acts as a natural barrier against wind and water.

2. Building terraces: Terracing involves creating stepped levels on the slopes, reducing the speed of water runoff and allowing water to be absorbed, thus preventing soil erosion in hilly or mountainous areas.

3. Using artificial barriers: Artificial barriers like walls or fences can slow down wind or water, reducing the rate of soil erosion, but they may not be as sustainable as natural solutions like vegetation or terraces.

Each of these methods is useful, but combining them is often the most effective solution for controlling soil erosion in mountainous regions.

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