GR4-SCI-QTR4

• Soil


  The material where plants grow and which provides them with physical support, water and nutrients
• Soil covers most of the land part of the earth
• Different types of soil

  • Differ in colors, texture, odor and ability to hold water
  • Some are good for planting while others are not
• Types of soil


  • Clay
  • Loam
  • Sand
• Clay


  Particles are tightly packed together, can hold much water and become sticky when wet, made up of very fine particles of rocks, can be used in making pots
• Loam


  Mixture of sand and clay, contains a large amount of decaying plants and animals, has a fine texture, can hold enough water and oxygen needed for plant crops
• Sand


  Particles are coarse and loose, easy to dig, not good for growing plants because it cannot hold water well
• Soil is a system into which energy and matter from the sun, atmosphere and living organisms penetrate and interact
• Layers of soil


  • Topsoil
  • Subsoil
  • Parent rock
  • Bedrock
• Topsoil


  Uppermost layer, rich with organic materials called humus and with minerals needed for plant growth, humus comes from decaying plant and animals, dark color indicates presence of humus, several kinds of plants can be seen growing on this layer
• Subsoil


  Located just below the topsoil, composed of loosely arranged rock, sand and clay, very rich with minerals that drain from topsoil, cannot support plant life on its own
• Parent rock


  Composed of rocks that are slowly breaking apart, contains very little weathering, does not contain necessary nutrients and water needed for plant growth
• Bedrock


  Lowest soil layer, made up of undisturbed large boulders and gravel, contains material good for constructing buildings and making roads, no plant life can survive in this layer
• Soil is important because it provides plants with physical support, water and nutrients to grow