7th Grade Chapter 1 Lesson 4


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7th Grade Chapter 1 Lesson 4

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