Questions Answers For All Chapters – Geography Class 7
Soils
Q. 1. Complete the following table.
Answer:
| Factor/Process | Role in the formation of soil |
| (1) Parent rock | The rock gets weathered depending on the hardness of the rock and the climate of the region. It turns into powdery material which further turns into soil. |
| (2) Regional climate | When the rock is exposed to a different climates, the same type of rock gives rise to different types of soil. |
| (3) Organic material | The organic material gets mixed into weathered powdery material and turn it into soil. |
| (4) Microorganisms | Microorganisms help in decomposing the dead remains of organic materials and get mixed into the soil to form humus. |
Q. 2. Why do the following occur ?
(1) To the west of Sahyadris, laterite soils are formed from basalt rock.
Answer: The humid climate and heavy rainfall in the Western Sahyadris cause intense leaching of basalt rock, leading to the formation of laterite soil. The iron content in the rock reacts with oxygen, giving the soil its characteristic reddish-orange color.
(2) Humus content in the soil increases.
Answer: The decomposition of plant and animal remains by microorganisms adds organic material, called humus, to the soil. Humus increases soil fertility and helps retain moisture.
(3) Soil formation process is faster in the equatorial climate.
Answer: In equatorial regions, high temperatures and heavy rainfall accelerate weathering and decomposition processes, leading to quicker soil formation.
(4) The salinity of the soil increases.
Answer: Excessive irrigation brings salts from deeper soil layers to the surface, making the soil saline. This process depletes soil fertility and affects plant growth.
(5) Rice is the staple diet of the people from Konkan.
Answer: The Konkan region has laterite and alluvial soils, which, along with heavy rainfall, create ideal conditions for rice cultivation. This makes rice the primary food crop in the region.
(6) Soil erosion
Answer: Soil erosion occurs when the topsoil is removed by wind or water. Factors like deforestation, overgrazing, and steep slopes contribute to erosion.
(7) Soil degradation.
Answer: Excessive use of chemical fertilizers, pesticides, and irrigation can lead to soil degradation. It reduces humus content, alters pH levels, and affects soil fertility.
Q. 3. Give information on:
(1) Measures of soil conservation.
Answer: Soil conservation involves protecting soil from erosion and degradation. Measures include:
- Constructing embankments and gully plugs to reduce soil washout.
- Planting trees to prevent wind erosion.
- Building Continuous Contour Trenches (CCTs) along slopes to reduce water runoff.
- Implementing watershed development programs to improve groundwater levels.
- Reducing the use of chemical fertilizers and adopting organic farming techniques.
(2) Organic manures
Answer: Organic manures are natural fertilizers derived from plant and animal waste. Examples include:
- Compost: Decomposed organic matter that enriches soil fertility.
- Vermicompost: Compost processed with the help of earthworms.
- Green manure: Crops like legumes that are grown and plowed into the soil to improve nutrient content.
(3) Place where you will get the information about the suitability of a soil for a particular crop.
Answer: Information about soil suitability for different crops can be obtained from:
- Agricultural universities and research institutes.
- Krishi Vigyan Kendras (KVKs).
- Government agriculture departments.
- Soil testing laboratories.
(4) Importance of soils for plant growth.
Answer: Soil is essential for plant growth because:
- It provides physical support for roots.
- It supplies essential nutrients and water.
- It facilitates the exchange of gases required for respiration.
- It harbors beneficial microorganisms that enhance plant health.
Q. 4. Complete the following table with reference to soil.
Answer:
| Action | Effect | Result (W.R.T. fertility) |
| Construction of embankments. | Protects soil from being washed away. | Protects fertility of soil. |
| Planting trees. | Wind speed decreased. | Protects fertility of soil |
| Farm land is kept fallow for some period. | Helps to maintain the pH balance and increase the proportion of humus. | Increases the fertility of soil. |
| Regular use of organic manures, vermicompost and compost. | Humus content increased. | Increases the fertility of soil. |
| Trenches are dug across a slope. | Check the velocity of water running along the slopes. | Protects fertility of soil |
| Litter is burnt in the farm. | Decreases the amount of organic material in soil. | Decreases the fertility of soil. |
| Decomposed vegetal litters, roots of plants and remains of animals. | Proves favourable for micro organism. | Increases the fertility of soil. |
| Excessive Irrigation | Salt content in the soil increases. | Decreases the fertility of soil |
| Chemical fertilizers used excessively. | Leads to the lowering of humus content in the soil. | Decreases the fertility of soil |
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