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SOILS PowerPoint Presentation


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  2. WHAT IS SOIL ? • The natural material on the surface of the earth. • The medium in which plants grow. • The end product of the influence of the climate (temperature, precipitation), relief (slope), organisms (flora and fauna), parent materials (original minerals), and time.

  3. COMPOSITION OF SOIL • Mineral particles – 45% (inorganic materials) • Organic matter – 5% • Water – 25% • Air – 25%

  4. AIR IN SOILS • About half of the total mass of soil is made of up vast holes. These holes are filled with both air, and water. The amount of air and the amount of water filling these spaces varies dramatically throughout the year, and from location to location, but averages about 50% each. It is essential for plant growth and living organisms. • The air found is soil is very different from the air found in the atmosphere. The air in soils is not exposed to moving air currents, and is much more moist, or humid than atmospheric air. It also tends to be very rich in carbon dioxide, and poor in oxygen because of consumption by bacteria. • Biota needs oxygen and gives off carbon dioxide by respiration and through the oxidation of organic matter through a process diffusion.

  5. WHAT ARE ORGANISMS? 1)Any contiguous living system (such as animal, fungus, micro-organism, or plant ) all types of organisms are capable of responseto stimuli, reproduction, growth and development, and maintenance of homeostasis as a stable whole.

  6. ORGANISMS IN SOILS • These include bacteria, fungi and earth worms. • More active during the warmer periods and can be seen endlessly in the well drained, well aerated soils. • Decomposition, Fixation and Development of Structure are all the processes which organisms are responsible for.

  7. ORGANISMS IN SOIL • Decomposition- worms, ants, mites(detritivores ) bury the leaf litter (detritus) which hastens the decay process. Their feaces increase the surface area of the detritus upon which fungi and bacteria can act . • Fixation- bacteria can be transformed from nitrogen in the air to nitrate for plant growth. • Development of structure – fungi helps to bind individual soil particles together to give a crumb structure .e.g. burrowing animals create passage ways which aid in the circulation of water and air.

  8. WHAT ARE NUTRIENTS • Chemical elements found in soil which are essential plant growth and the maintenance of soil fertility

  9. WHERE DO NUTRIENTS COME FROM ? The main sources of nutrients are : • Weathering of minerals in soil • The release of nutrients on the decomposition of organic matter and humus by soil organisms • Rainwater • Artificial application of fertilizer

  10. NUTRIENTS IN THE SOIL • Primary Nutrients Nitrogen (N) Phosphorus (P) Potassium (K) • Micronutrients Zinc (Zn) Iron (Fe) Copper (Cu) Manganese (Mn) Boron (B) Molybdenum (Mo) Chlorine (Cl) • Secondary Nutrients Sulfur (S) Calcium (Ca) Magnesium (Mg)