Soil Class 7 Notes CBSE Science Chapter 9 (Free PDF Download)

Soil:

Soil is the loose material present on top of Earth’s crust and covers most of the land. It is composed of both organic and inorganic matter that provides both structural and nutritional support to vegetation and thus is very important for life to exist on Earth. The chemical and physical properties of soil vary greatly based on regions they are found in.

Soil Formation: 

Soil is formed by disintegration of rocks due to weathering and the process of natural erosion. The conditions under which the weathering takes place determine the properties of soil. Some of the main processes are as follow;

• Physical Weathering: It is caused by change in temperature or pressure or both due to physical agents like sun, wind, ice etc. that increase or decrease the volume of rocks and thus disintegrate them.

• Chemical Weathering: This takes place when different chemical compounds, for instance rainwater combine with the minerals present in the rocks to form new minerals or salts.

• Biological Weathering: This process is carried out by the action of living organisms like plants, animals and other microorganisms which secrete or release acids that in turn disintegrate the rocks.

Soil Profile:

The vertical section of soil lying above the underlying rocks having distinct layers determined based on their properties and grain size called soil horizons is called the soil profile. The main layers found in any soil profiles are as follows;

• Humus or organic matters

• Topsoil

• Subsoil

• Parent material

• Bedrock

Types of Soil:

There are mainly three types of soil;

1. Sandy Soil - This soil is light, dry, warm and often acidic and has fewer nutritional contents. Their size varies from $0.2$ to $2.0$ mm in diameter. They are also known as light soils because of a higher proportion of sand than clay which weighs more. They are very easy to work with and have quicker water drainage and because of that only, the nutrients get washed away by rain. Although addition of additional organic matter can give a boost for plant growth.

2. Clayey Soil - This is a heavy soil type richly loaded with nutrients. They stay wet and cold during winter and dry out in summer. Over $25%$ clay is found in this soil and the spaces between particles hold a large amount of water. And for that reason, the water drainage is slow and often takes longer to warm in summer.

3. Loamy Soil - This soil is a mixture of sand and clay and which helps in minimizing the negative effects of both of them. Based on the proportion of sand and clay, the water drainage can be controlled. This soil type is easy to work with and is mostly preferred by the gardeners.

Uses of Soil:

The various properties of soil and their richness with nutrients, minerals, water and microorganisms make them useful in many fields.

• Agriculture: Soil not only helps plants hold but also provides their roots with water, air, nutrients and proper nourishment to grow and produce.

• Building: Soil is largely used to make red bricks that are used for building processes. This soil is compacted to increase its density and which in turn improves the load support.

• Pottery: Clay soil is mixed with water to make ceramics or pottery. After the shaping is done, it is left to dry and thus retains the shape. Some examples of pottery are vase, bowl, cup, sculptures etc.

• Medicine and Beauty Products: Some microorganisms present in soil help in fighting the harmful bacteria. It is used in preparation of many skin ointments, antitumour drugs and tuberculosis drugs.

Soil Chapter Class 7 Notes

These revision notes give an overview of the chapter and highlight the key points under each sub-topic. The experts have explained each topic and category in a separate paragraph and have created a pointwise description of the same. Let’s give you an overview of the Class 7 Science Chapter 9 Soil notes.

These revision notes explain the meaning of the term soil and its importance. Soil is the uppermost crust covering the earth and is made up of humus and rock particles. These notes further explain the process of soil formation which includes the disintegration of the parent rock.

Soil Class 7 notes also explain the constituents of soil and the soil profile. The soil is made up of living and non-living matter and can be classified into various types.

By going through these crisp and precise revision notes, students can learn about different types of soils, their characteristics, and their uses. It would help them in answering any questions from this chapter in their examination.

Why are Revision Notes for Class 7 Chapter 9 - Soil Important?

• Vedantu’s Revision Notes for Class  7 Chapter 9 - Soil are the finest material to understand and practice the topics in the best way.

• The material carries all the information in detail and pointwise.

• All the cases of the material are solved in the simplest way which explains the term clearly.

• Vedantu Revision Notes for Class  7 Chapter 9 - Soil provides all the main topics so that the student can focus on it and prepare for the exam. 

Conclusion

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