Soil class 5

soil its importance

1. SOIL

2. Soil is a mixture of minerals and organic material that covers much of Earth’s surface. Minerals are bits of rock , and organic material is the remains of living things that have died. Soil is not as solid as rock. It has many small spaces, called pores, that hold water and air. In some places on Earth, a thin layer of soil only 6 inches (15 centimeters) thick lies on top of rock. In other places, though, soil may be hundreds of feet deep. Introduction

3. The mineral part of soil forms from rocks. Such forces as wind, water, and temperature changes break rocks down into tiny particles, or bits. The smallest particles are called clay . Medium-sized particles are called silt. The largest particles are called sand . Different types of soil contain different mixtures of clay, silt, and sand. COMPOSITION

4. HUMUS The organic part of soil forms when plants and animals die. Their bodies decay, or break down, and mix with the rock particles. The organic material, called humus, helps to form the pores in the soil. It keeps the soil soft and loose. Humus also provides the nutrients used by plants.

5. SOIL FORMATION Without soil, most life on Earth could not survive. Soil provides a place for plants to grow. It holds water in place for their roots. It contains nutrients, or food substances, needed for their growth. Soil also provides a home for many animals and other living things. Soil forms slowly. A layer of soil that is 1 inch (2.5 centimeters) thick may take 500 to 1,000 years to form. For this reason it is important to protect soil from erosion —being blown or washed away.

6. LAYERS OF SOIL Soil is made up of layers. The layers rest on solid rock, called bedrock. A layer of broken rock rests on the bedrock. Some of this rock may have gone into forming the soil above. The soil above the broken rock is called subsoil. Subsoil contains mostly minerals and a small amount of humus. Only the deepest plant roots reach the subsoil. The top layer is called topsoil. Topsoil contains a lot of humus. It is the layer where plants grow.

7. Soil erosion It is a process in which the top fertile layer of soil is lost. Due to soil erosion, the soil becomes less fertile. The top layer of soil is very light which is easily carried away by wind and water. The removal of topsoil by the natural forces is known as soil erosion.

8. Grand canyon (united states)

9. Causes of soil erosion Various agents, like wind, water, deforestation , overgrazing by cattle, etc., cause soil erosion. The various factors of soil erosion are:

10. Wind When strong winds blow, the topsoil along with the organic matter is carried away by the wind. This happens more often when the land is not covered with grass or plants. Such conditions are very common in desert and semi-desert regions where strong winds blow very frequently.

11. . Water When it rains in the hilly areas, the soil gets washed away towards the plains. The running water deposits the mineral-rich soil in the riverbed and over the years this deposition of soil can change the course of the river. This can lead to floods which cause the destruction of life and property and leads to loss of soil fertility.

12. Overgrazing When cattle is allowed to graze on the same field repeatedly, all the available grass, including the roots are eaten by them. This loosens the topsoil which is taken away by wind and flowing water, leading to soil erosion.

13. Deforestation Humans have taken land from the forest to cultivate in order to feed the ever-increasing population and to build houses, industries, etc. Cutting down of trees on a large scale for these purposes is deforestation. The roots of trees hold the soil together, thus preventing the soil from getting uprooted. When large areas of the forest are cleared, the topsoil gets eroded by wind and flowing water.

14. P revention of soil erosion is also called conservation of soil. The soil erosion can be prevented by the following ways: Soil conservation

15. Afforestation Planting new trees and plants is afforestation. We live because plants live. If the plants die, all living things will also die. Thus, whenever trees are cut down new trees should be planted. Planting trees in hilly areas are most effective for conservation.

16. Terrace Farming In hilly areas, farming is done by cutting steps on the slopes of the hills. This slows down the flow of water and soil removed from one step is deposited on the next step. Thus, the soil is never completely lost. This is terrace farming.

17. The cover of plants and trees around the field also breaks the speed of strong winds and protects the soil from being blown away.

18. Embankments Big strong structure called embankments along the banks of the river can protect fields from the floods. These embankments prevent the fast overflowing rivers and rainwater from washing away a huge amount of rich fertile soil.

19. Van Mahotsav It is an annual tree planting festival started by the Government of India. The aim of this programme is to create awareness about the need for conservation of forest and soil.

20. Building Dams Dams are built to prevent floods, which not only damage the crops but also wash away the topsoil.

21. A PRESENTATION BY DIVYA KUMAR THANK YOU :)