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Soil has covered the surface of the earth like a blanket. As a result of this, it connects the rocks inside and lives on the earth systematically. It works like a medium for the organic plants and animals for their existence. We shall discuss about the formation of soil, constituents of soil and their utility.
CREATION OF SOIL
Soil is created from rocks. Different natural factors like earthquake, stream of water, wind, ice and organic materials cause the rocks to break. Big rocks turn into pretty pebbles. Pebbles turn into sand and finally we get clay from the sand. Both sand,clay and different organic materials create soil.
COMPOSITION OF SOIL
The soil is made up of mineral particles, organic matter, solution of various inorganic salts in water, air and living organism. Thus, the soil has physical as well as chemical properties. The physical properties of soil include its texture, structure, colour, porosity, water holding capacity and presence of soil organism. The chemical properties, like acidity and alkalinity of the soil, have a relation with the type of vegetation and crops grown on it. Temperature may affect biological, physical and chemical composition of the soil. In humid regions, the soil becomes acidic due to leaching of soluble basic salts, like calcium carbonate. Saline soils are mostly alkaline.
Take some dry soil. Keep it in a metal container(katori) and heat it on a flame or over a candle cover it with a lid. You will observe drops of water on the inner side of the lid. For a better result, a metal tumbler or a heat resistant glass test tube can be used. You may conclude from this activity that even apparently dry soil also contains some water.
The clay particles exhibit properties of particles in colloidal state. This includes water retaining capacity as well. The texture of the soil
depends upon the relative proportions of particles of different sizes. Thus, the soil can be classified as sandy, loamy and clayey depending upon the amount of sand silt, clay and humus in it. A loamy soil is most suitable for plant growth as it contains some large particles to keep the soil porous and smaller particles for increasing its water holding capacity.
ACTIVITY - 2
Dig some soil from your garden or field. Put it in a glass tumbler or a wide mouth bottle filled with water, observe the evolution of air bubbles. You can repeat this activity by taking soils from different areas, like near a pond or near the drains. Make a comparison in the number of air bubbles evolved by taking some amount of soil from different places. This activity gives an idea that soil contains air.
COMPOSITIONS OF SOIL
TYPES OF SOIL
We are know that soil is divided in to three types. But in the past it was categorized as fertile and sterile soil.According to the fertility of the soil. Soil can also be divided into red, black, yellow and gray according to the color of the soil.
This soil is stored in the river valley or low lands of the plateau or higher regions. It is very fertile. One can find clay, sand and small pretty pebbles in it. It is found in Uttarpradesh, Hariyana, Bihar, West- Bengal & Andhrapradesh.
This soil is created by the discharges of Volcanoes.One can find magnesium and iron in it. It is very useful for the production of cotton and sugar-cane. It can keep water very well. This soil is available in Maharastra, Andhrapradesh, Madhyapradesh and Gujarat.
Red soil is created by the erosion of Igneous rock. It looks red as there enough iron-oxide. This soil is very fertile as it is constituted by small ingridents. This soil can be found in Tamilnadu, Karnataka, Andhrapradesh, Orissa & Jharkhand.
This is red color.This is a mixture of clay and pretty pebbles in it. It is sterile and not fit for agriculture.This soil can be found in the mountainous regions of Orissa, Karnataka, Kerala and Assam.
This soil is created by the decomposition of dry leaves and organic materials. It is very fertile as it is mixed with organic materials. This soil can be found in the mountain regions of Mahalaya, Arunachal Pradesh and Jammu & Kashmir.
This soil is mainly constituted by the mixture of sand. There is no organic materials in this soil. This soil can not be used in agricultural purposes due to lack of water. This soil is seen in the dry regions of India like Rajasthan, Punjab and Hariyana.
Soil is very useful and very important natural wealth. It is formed in a natural process.The plants grow on the soil collecting water, mineral salt, cultivation is done on the surface of the earth. We can’t grow paddy,jute and wheat without soil. Besides this potatoes, ground nuts,ware also cultivated on the sandy soil. Vegetables are plenty cultivated on different types of soil.Beside this soil is used to build houses, roads and earth and to make pots. Different kinds of mineral wealth are also collected by digging the soil.Different kinds of micro organisms like ants, white-ants also live in the soil.Besides this,cows,buffalos,camels and horses live on the land. So soil is very very useful to us.
The continuous transition of soil from a certain place in natural way is called soil erosion. It is caused by water and wind.Rain water,river current sea wave,strong wind etc are main sources of agent of soil erosion.Heavy rain separates the soil particle from the soil. This soil erosion happens at the two sides of river.Sea waves beating continuously at the shore wash away the soil from there.So soil erosion happens.In summer the dust blows away by the wind from the surface of the ground.Thus the soil becomes in sterile. The dust from the desert blows away by the soil erosion .At waste land and at the place without plant and trees, it causes by deforestation.
Soil pollutes like air and water. The microbes,animals and plants are affected with the polluted soil.
Plants and crops do not grow in the polluted soil. The fruits,vegetables and crops produced from the affected soil are also polluted.
3. The industrial waste also pollutes the soil. The solid and liquid waste from paper mills, ash from thermal power station, unrefined oil from oil refinery, acid mixed water from leather and rubber industries pollute the soil.
4. Different kinds of fertilizer and pesticides in order to produce more, causes soil pollution.
5. Except the industrial waste different types of materials like lead, zinc, arsenic, cupper, cadmium dust from the mines also pollute the soil.
6. Maximum use of plastic bags also pollutes the soil.
7. Sand spreads over the field due to flood and slain water of the ocean pollute the soil.
By 8th Students