Soil is a mixture of minerals from rocks and organic material from living things that have died. It covers much of Earth's surface in layers, with topsoil near the surface containing more humus. Soil forms slowly over hundreds of years and provides nutrients and housing for plants and animals. Factors like wind, water, deforestation, and overgrazing can cause soil erosion, removing the nutrient-rich topsoil. Conservation efforts like afforestation, terrace farming, and building dams can help prevent soil erosion.

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

8. 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.

10. 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

12. 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.

15. 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.

17. Grand canyon (united states)

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

19. 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.

20. . 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.

21. 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.

22. 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.

24. Prevention of soil erosion is also called conservation of
soil. The soil erosion can be prevented by the following
ways:
Soil conservation

25. 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

26. 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.

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

28. 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.

29. 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.

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

32. A PRESENTATION BY DIVYA KUMAR
THANK YOU :)