Science and Elementary Technology

Soil is one of the non-living things. It is useful to plants, 

people and other animals. Plants grow in soil. 

People and other animals depend on plants for food.

There are three main kinds of soil:

 1. Loam is chiefly a mixture of sand and clay. 

It can hold enough water and air for plants. It feels smooth.

 2.  Clay is made up of very fine particles. It can hold a lot of water but very little air.

 It feels sticky when wet and forms clumps when dry. 

3. Sandy soil is made up of very small rock particles. 

They are bigger than clay particles. Sand is found in desert areas.

 Sand cannot hold much water but it can hold much air. It feels gritty.

1. Collect samples of clayey, sandy and loamy soils.

 2. Take a fistful of soil from one of the samples. 

 3. Remove any pebbles and rocks from it. 

 4. Now add water drop by drop and knead the soil.

 5. Try to make a ball from the soil. 

 6. On a flat surface roll the ball into a cylinder. 

 7. Repeat this activity with other samples.

 Which soil is suitable for making different shapes? Why?

The clayey soil does not allow water to pass through it easily. 

This is because its particles are closely packed. 

It has high water-holding capacity. It is suitable for cultivation.

 Soil that is used for cultivation should be fertile.

 Fertile soil should have the following characteristics: 

 1. It should have adequate amount of humus.

 2. It should have high water-holding capacity. 

 3. It should be well aerated.

 4. It should be deep because deep soil enables plants to grow well.

5. It should be easy to dig.

You might have seen tall trees grown on all sides of a field. 

These are grown to reduce the speed of blowing winds. 

They act as wind breakers. 

Soil erosion is maximum on hill slopes due to the speed of water being high. 

 Here the hills are cut into steps by farmers.

 It reduces the speed of flowing water and prevents soil erosion.

Clay: Soft soil when it is wet and hard when it is dry. 

‹ Humus: A component of soil, made up of dead plant and animal remains.

 ‹ Loam :  A kind of soil which is a mixture of sand and clay with some humus. 

‹ Sand:  Finely crushed stones found on beaches. 

‹ Soil : The topmost layer of the earth’s surface. 

‹ Weathering :  Breaking of rocks into tiny pieces to form soil.

‹ Soil is the topmost layer of earth’s surface. 

‹ Soil contains air, water, clay, sand, stones and humus. 

‹ There are three types of soil, namely loam, clay and sand. 

‹ Fertile soil should have high water-holding capacity and adequate amount of humus.

 ‹ The process of carrying away soil by wind, water or other agents is called soil erosion.

 ‹ Water and wind are two main agents of soil erosion. 

‹ Deforestation, overgrazing and bushfires are main causes of soil erosion.

1. Define soil.

 2. What are the different types of soil? 

 3. What is the composition of soil? 

 4. Write three uses of soil.

 5. Soil is home to many animals. Can you name any three animals? 

 6. Write any three characteristics of fertile soil.

 7. Mention one agent of soil erosion

8. List different types of soil erosion. 

 9. List three methods of preventing soil erosion.

2. It is the topmost layer of the soil. 

 4. Soft when it is wet and hard when it is dry. 

 5. Component of the soil, 

made up of dead plants and animal remains.

Down

1. A kind of soil which is a mixture of sand and clay with some humus

3. Finely crushed stones found on beaches.