1. The Nitrogen Cycle Chapter 2.3

2. What accounts for the differences?

3. What is fertilizer?  One of the main ingredients is Nitrogen!  After carbon, hydrogen and oxygen, nitrogen is the most common element found in food chains.  It cycles too!

4. Plants  Plants use nitrogen (N), potassium (K) and phosphorous (P) to help them grow. These are common elements in fertilizers.  The Earth’s atmosphere is 80% nitrogen gas, but most organisms can’t use the nitrogen directly

5. Human Impact on the Nitrogen Cycle  Most plants can live very well in low nitrogen environments.  Artificial fertilizers have altered the process.  The burning of fossil fuels in our cars and by factories also emits nitrogen back into the environment.  There is now an additional 140 TONNES of nitrogen in the Earth!

6. Effects on Soil  There are limits to how much plant growth can be increased by adding more nitrates.  More doesn’t always lead to increased production.  “Nitrogen Saturation”  Damages soil, and tree roots, stunts tree growth, and causes needles on spruce trees and other conifers to turn yellow and fall off.  Increase in soil acidity.

7. Effects on the Atmosphere  Acid precipitation  Kills fish, birds, amphibians, other organisms.  Loss of sugar maple trees in Ontario and Quebec  Lake pollution  Only solution is to add limestone powder to lakes to neutralize

8. Effects on fresh-water ecosystems  1970’s huge increase in algae and weeds.  Increased nitrates from fertilizer caused the spike.  Blocks sunlight from entering ecosystems in ponds. Plants can’t perform photosynthesis.

10. Effects on Marine Ecosystems  Development of Algal blooms.  Robs the ecosystem of oxygen.  Loss in fish and shellfish.

11. Complete Questions  Page 65 questions 1 to 6  Read 2.4 and complete questions 1 to 4 page 68.  http://soil.gsfc.nasa.gov/NFTG/nitro cyc.htm http://soil.gsfc.nasa.gov/NFTG/nitro cyc.htm