1. What is Nitrogen? N for Nitrogen-element on Periodic Table Necessary building block in living things Air = 78% Nitrogen gas “Free Nitrogen” – not combined with any other element

2. Why do we need Nitrogen? All living organisms need nitrogen in order to build proteins and build DNA Most animals get the nitrogen they need by eating plants.

3. Available Nitrogen Nitrogen must be combined with something else in order for it to be used Most organisms can NOT use the nitrogen in the air Nitrogen must be “fixed” – needs to be combined with other elements

4. Nitrogen Cycle The process by which nitrogen is removed from the atmosphere, fixed in the soil by bacteria, incorporated in other living things, and then released back into the atmosphere.

5. 1)How does atmospheric nitrogen become usable on Earth? N 2 gas must be “fixed” (converted) by microorganisms (bacteria) into ammonium & nitrates that plants can use. 2) What organisms are involved in the movement of nitrogen between the air and soil, and back to the air? Bacteria: Nitrogen –fixing and decomposers

7. 3) How do nitrogen-fixing bacteria on root nodules function in the nitrogen cycle? Take in nitrogen gas (N 2 ) from the air and convert it into ammonium and nitrate. 4) Effects on nitrogen cycle if large volume of nitrogen rich fertilizer runs off land and into surface water? Would lead to eutrophication (algal blooms) that consume dissolved oxygen & lead to “dead zones” (areas where there is too little DO to support fish/shellfish).

8. 5) How do animals, like the deer pictured, contribute to the nitrogen cycle? Deer & other animals get nitrogen from the plants they eat. Their poop adds nitrogen (in the form of ammonia) back to the soil. 6) Livestock farming creates large amounts of animal waste. How would this affect the nitrogen cycle? Livestock farming contributes HUGE amounts of ammonia (containing nitrogen) to the soil through POOP! Excess animal waste in runoff = overgrowth of algae in nearby waterways and this can result in eutrophication.