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Subject:

science-chemistry

Class:

class VII

Key Concepts

clayey, percolation, humus, soil erosion, moisture, absorption, water retention, Loamy

essential questions

1.Why is soil important to all living things?
2. Why do plants grow in soil?
3. What is a healthy soil?
4. How do we classify soils?

Remembering:

  1. Define weathering. List the factors that cause weathering.
  2. What is humus?
  3. List the names of various types of soil found in India.

understanding:

  1. Which soil allows more water to percolate- sandy soil or clayey soil. Explain why?
  2. What is soil profile?
  3. Draw a well labelled diagram of various layers of soil.
  4. Write the difference between: a)  Clayey and Loamy soil   b) C- horizon and A-horizon
  5. What is a percolation rate?
  6. Write True or false: a) waterlogging occurs in sandy soil.

b) The soil is a natural resource

c) Since clay holds more water, it is very good for plants as they get plenty of water.

d) Humus is formed by the action of insects on the soil

e) Soil without humus is not fertile.

Application:

  1. Why is sandy soil unable to hold water in comparison to clayey soil?
  2. Why is A horizon considered to be the most important layer for the plants to grow?
  3. If the percolation rate in soil is slow, then what can we conclude from the same?
  4. Why is soil erosion a threat for human race? Explain with an example

Analysis:

  1. It is said plastics pollute the soil by killing the micro organisms in soil. Can you find reasons to justify this statement.
  2. Can you give reasons why there is a difference in the absorption of water in two different patches of land?
  3. During hot summers the air above the land is shimmering. Can you give the reason behind it.
  4. Can you explain in detail how absorption and percolation of water are connected with each other. Give examples of soils to explain the concept.
  5. What is the difference between rate of percolation and the amount of water retained?

Evaluation:

  1. Rice is a Kharif crop. So from this information, what all can we derive regarding the soil, rice as a crop needs to grow in?
  2. An agricultural scientist was examining two types of soil, Soil A and Soil B. He made following observations regarding these two soils.

100gms of Soil A is  able to retain 20% of the moisture when kept under the sun for an hour.

100gms Soil B is able to retain 10% of the moisture when kept under the sun or an hour.

What can we infer from these statements about the soil types of A and B.

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