Soil As A Resource
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Soil is the top layer of earth's crust consisting of organic and inorganic matter that supports plant growth and living organisms. Soil formation is influenced by factors like relief, parent rock, climate, vegetation, and time. The major soil types in India are alluvial, black, red and yellow, laterite, arid, and forest soils. Alluvial soils are the most widespread and fertile soils, deposited by Himalayan river systems in northern India. Black soils, also known as regur soils, are clay-rich and moisture-retentive, found in the Deccan trap region. Red and yellow soils develop in dry, crystalline rock areas with low rainfall. Laterite soils form in hot,
Soil As A Resource
- 1. Soil as a resource
- 2. What is soil? Top most layer of earth crust consisting of organic and inorganic matters is called soil. Soil is a renewable resource. Soil is a living system. It is the medium of plant growth and supports different types of living organisms on the earth. Unweathered parent bed rock Top soil the upper soil layer Subsoil weathered rocks sand and silt clay Substratum weathered parent rock material
- 3. Factors of Soil formations Relief, Parent rock or bed rock, Climate, Vegetation and other forms of life and Time are important factors in the formation of soil. Change in temperature, Actions of running water, wind and glaciers, Activities of decomposers etc. Chemical and organic changes.
- 4. Classification Soils Major types of Soils found in India. Alluvial Soil Black Soil Red and Yellow Soils Laterite Soils Arid Soils Forest Soils.
- 5. Alluvial Soils Most widely spread: The entire northern plains are made of alluvial soil. Deposited by Himalayan river systems– the Indus, the Ganga and the Brahmaputra. Piedmont plains in the upper reaches of the river valley, the soils are coarse are Duars, Chos and Terai. According to their age alluvial soils can be classified as old alluvial ( Bangar) and new alluvial ( Khadar). The bangar soil has higher concentration of kanker nodules than the Khadar. Khadar has more fine particles and is more fertile than the bangar. Alluvial soils as a whole are very fertile having potash, phosphoric acid and lime. Due to its high fertility, regions of alluvial soils are intensively cultivated and densely populated.
- 6. Black Soils These soils are also known as regur soils or black cotton soil. Climatic condition along with the parent rock material are the important factors for the formation of black soil. This type of soil is found in the Deccan trap (Basalt) region. The black soils are made up of extremely fine i.e. clayey material. They are well-known for their capacity to hold moisture. In addition, they are rich in soil nutrients. These soils are generally poor in phosphoric contents. They develop deep cracks during hot weather, which helps in the proper aeration of the soil. These soils are sticky when wet and difficult to work on unless tilled immediately after the first shower or during the pre-monsoon period.
- 7. Red and Yellow Soils Red soil develops on crystalline igneous rocks in areas of low rainfall in the eastern and southern parts of the Deccan plateau. Yelllow and red soils are also found in parts of Orissa, Chhattisgarh middle Ganga plain. These soils develop a reddish colour due to diffusion of iron in crystalline and metamorphic rocks. It looks yellow when it occurs in a hydrated form.
- 8. Laterite Soils Laterite has been derived from the Latin word ‘later’ which means brick. The laterite soil develops in areas with high temperature and heavy rainfall. This is the result of intense leaching due to heavy rain. Humus content of the soil is low because most of the micro organisms, particularly the decomposers, like bacteria, get destroyed due to high temperature. Laterite soils are suitable for cultivation with adequate doses of manures and fertilizers. These soils are mainly found in Karnataka, Kerala, Tamil Nadu, Madhya Pradesh, and the hilly areas of Orissa and Assam. After adopting appropriate soil conservation techniques particularly in the hilly areas of Karnataka, Kerala and Tamil Nadu, this soil is very useful for growing tea and coffee. Red laterite soils in Tamil Nadu, Andhra Pradesh and Kerala are more suitable for crops like cashew nut.
- 9. Arid Soils Arid soils range from red to brown in colour. They are generally sandy in texture and saline in nature. In some areas the salt content is very high and common salt is obtained by evaporating the water. Due to the dry climate, high temperature, evaporation is faster and the soil lacks humus and moisture. The lower horizons of the soil are occupied by Kankar because of the increasing calcium content downwards. The Kankar layer formations in the bottom horizons restrict the infiltration of water. After proper irrigation these soils become cultivable as has been in the case of western Rajasthan.
- 10. Forest Soils These soils are found in the hilly and mountainous areas where sufficient rain forests are available. The soils texture varies according to the mountain environment where they are formed. They are loamy and silty in valley sides and coarse grained in the upper slopes. In the snow covered areas of Himalayas, these soils experience denudation and are acidic with low humus content. The soils found in the lower parts of the valleys particularly on the river terraces and alluvial fans are fertile.