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Class IV Science -Soil


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Summary of chapter Soil of Class IV CBSE,

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Class IV Science -Soil

  1. 1. Soil
  2. 2. Formation of Soil  Soil is defined as the top layer of the Earth ’s surface, which consists of sand, remains of dead plants and animals, and minerals with some amount of water and air in it.
  3. 3. Types of Soil Three types types of soil, depending on the size, feel, and colour of the soil particles 1. Gravel consists of tiny stones and does not hold water. 2. Sand is light and dry. Water passes easily through this kind of soil as particles are rough. 3. Clay particles are extremely fine. Water does not flow freely through this soil. Soil that consist s of clay, sand and humus is called loam. Loamy soil is good for growing plants.
  4. 4. Composition of soil Soil is made of  Gravel, sand and clay particles  Humus (remains of dead plants and animals)  Water  Air, minerals Gravel
  5. 5. Soil  Top soil  Uppermost layer  Contains sand, clay, humus and water  Gives nutrients to plants.  Subsoil  Middle layer  Contain broken pieces of rock.  Less humus  Bedrock  Bottom layer  Large pieces of rock  Not much water.
  6. 6. Soil Erosion  The removal of the fertile topsoil by the action of wind and water is called soil erosion.  Strong winds, heavy rainfall and cutting down of trees increase soil erosion.
  7. 7. Soil Conservation  Protection of soil is known as soil conservation. Steps to conserve soil.  More number of trees should be planted to replace the ones that are cut down.  Crop Rotation  Different types of crops should be grown on a farmland so that the soil gets time to recover its fertility.  Trees and bushes should be planted in open land to prevent wind to blow away topsoil.  Dams should be built across rivers to prevent floods.