Soil As A Resource
* Soil is formed over millions of years by agents like weathering of rock by natural variation in temperature, wind, glaciers and running water.
Basics for classification of soil are:
* Physical and chemical properties
* Age
* Texture
* Colour
Different types of soils in India are:
* Alluvial
* Black soil
* Red and yellow soil
* Laterite soil
* Forest soil
Soil Erosion and Conservation
* The loss of soil cover due to natural agents like wind and running water is called soil erosion.
* The roots of plants and trees keep the soil moist and hold the soil particles together.
Humans destroy vegetation cover by:
* Deforestation
* Overgrazing
* Mining activities
* Without vegetation cover, soil becomes dry and loose, and gets easily eroded.
* Defective farming methods, like ploughing up and down a slope increase the rate of soil erosion.
* The formation of deep channels in clay soils by running water is called gully erosion.
* The washing away of the entire sheet of top soil in region by water is called sheet erosion.
* Soil conservation is the prevention of soil erosion.
Methods of Soil conservation are:
* Terrace farming
* Contour ploughing
* Strip cropping
* Shelter belts
* Terrace farming and ploughing land contour lines reduce the speed of water flowing down the slope and help in soil conservation.
* In strip cropping, strips of grass standing between crops reduce the force of wind and thus prevent soil erosion.
Soil
* Soil is the thin layer of matter that covers the earth’s surface.
* Soil is formed by the weathering of rocks and minerals. The break – down of surface rock due to various factors is called weathering.
* The major factors that affect soil formation are: The parent rock, Climate, Relief, Flora, Fauna and micro – organisms, Time.
* Soil degradation is caused by: Deforestation, Overgrazing, and Excessive use of chemicals, fertilisers and pesticides, Rain wash, Landslides, floods.
* The methods of Soil conservation are: Mulching, Contour barriers, Rock dams, Terrace farming, Intercropping, Contour barriers, shelter belts.
Soil – Soil Profile
Soil is used in:
* Agriculture
* Construction
* Pottery
* Weathering is the process of soil formation that occurs when rocks are broken down due to the action of wind, water and climate.
* A vertical section that shows different layers of soil is called a soil profile.
* Each layer of soil is called a horizon.
* The topmost of soil is called topsoil or A – horizon. It contains humus, which is made up of rotting plants and animals. This layer of soil is soft and porous, and can retain more water than other layers.
* The second layer of soil is harder and less porous than the soil. It is called the middle layer or B – horizon.
* The third layer of soil is mostly made up of rocks and is called C – horizon.
* The bottom layer of soil is very hard and is called rock.