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7th Grade Chapter 1 Lesson 4
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7th Grade Chapter 1 Lesson 4



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7th Grade Chapter 1 Lesson 4 Presentation Transcript

  • 1. 7 th Grade Chapter 1 Lesson 4 Pgs. 21-25 For Student Use Only
  • 2. Soil Nutrients
    • The mineral and organic parts of soil together supply nutrients for plants.
      • The three most important nutrients:
        • Nitrogen
        • Phosphorus
        • Potassium
      • Plants remove these three nutrients as they grow.
      • They are called primary plant food elements.
  • 3. Soil Nutrients
    • Because Nitrogen, Phosphorus, and Potassium are not naturally replenished quickly, farmers and gardeners add fertilizers.
    • Fertlizers are designed for different purposes with different amounts of the three nutrients.
  • 4. Soil Nutrients
    • Nitrogen
      • Stimulates growth in stems and leaves
      • Gives plants healthy green color
      • Too much can cause the plant to grow too much
      • There is also a Nitrogen Cycle so that nitrogen an be recycled through out the world
  • 5. Soil Nutrients
    • Nitrogen Cycle
      • This is how Nitrogen is moved from the air to the soil and back again.
      • Nitrogen in the air must become “nitrates” (nitrogen compounds) in order to be used by plants.
  • 6. Soil Nutrients
    • Forming Nitrates
      • In the air:
        • Energy from lightning causes Oxygen and Nitrogen to bond and the nitrates fall with the rain.
      • In the soil:
        • Nitrogen is converted to nitrates by Nitrogen-fixing bacteria that live in the nodules (bumps) of legumes (peas, beans, etc.)
        • Ammonia in the soil is also converted to Nitrates by Nitrifying Bacteria
  • 7. Soil Nutrients
    • Nitrogen back to the Air
      • Denitrifying Bacteria are responsible for taking Nitrogen Compounds and turning them into atmospheric Nitrogen.
    • Nitrogen often passes through the entire system (soil-plant-animal-people) many times before it goes back into the air or soil.
  • 8. Soil Nutrients
    • NOTE: Bacteria such as nitrifying and denitrifying are important for soil.
      • Denitrifying bacteria are anaerobic (do not need oxygen) and need to be balanced with nitrifying bacteria.
  • 9. Soil Nutrients
    • Phosphorus
      • Is essential for cell division and cell growth
      • Is needed to help plants produce fat and turn starched to sugars
      • Helps fruit get ripe and firm
      • Comes from minerals in the ground, in particular it comes from apatite (a calcium phosphate compound found in rocks)
  • 10. Soil Nutrients
    • Potassium
      • Helps form chlorophyll (green pigment that helps plants make food)
      • Helps overall health of plant
      • It is found in the ashes of fruit, vegetables, and grains, however, these do not exist naturally in enough quantity so many farmers add potash to their fields.