1.7 Nitrogen Cycle PDF

1.7 Nitrogen Cycle  Learning Goals Explain how nitrogen cycles through an ecosystem  Nitrogen Used for protein and DNA formation in organisms The atmosphere has a lot of Nitrogen → 78%! ○ But can not be used directly by organisms Nitrogen cycle: ○ how nitro...

1.7 Nitrogen Cycle  Learning Goals Explain how nitrogen cycles through an ecosystem  Nitrogen Used for protein and DNA formation in organisms The atmosphere has a lot of Nitrogen → 78%! ○ But can not be used directly by organisms Nitrogen cycle: ○ how nitrogen enters and leaves the atmosphere ○ complex pathway that involves many different types of bacteria  The Nitrogen Cycle 1. Nitrogen enters the soil from the atmosphere Certain bacteria use the process of nitrogen fixation to convert nitrogen gas into a variety of nitrogen-containing compounds, including nitrates, nitrites and ammonia.  The Nitrogen Cycle 2. Nitrogen moves up the food chain Once in the soil ecosystem, the nitrogen-rich compounds are available to producers. It is passed from producer to consumers.  The Nitrogen Cycle 3. Nitrogen is excreted and enters back into the ground Animals excrete the excess nitrogen in the form of urea or ammonia The nitrogen-rich compounds found in the body of a dead organism or animal waste are taken in by decomposers and the nitrogen is released back into the soil for use by plants.  The Nitrogen Cycle 4. Nitrogen enters back into the atmosphere The nitrogen compounds in the soil are converted back into nitrogen gas by denitrifying bacteria which then re-enters the atmosphere. The Nitrogen Cycle  Human Influence Humans add nitrogen to the soil as fertilizers to help plants grow. Excess nitrogen can enter run-off ○ Run-off is water from rain or snow that flows over the surface of the land and carries pollution to a nearby body of water  Human Influence The addition of nutrients (such as nitrogen) to an aquatic ecosystem can lead to eutrophication in nearby lakes and ponds This can cause an increase growth of algae The layer of algae that grows on the surface of the water is called an algal bloom The algal bloom blocks sunlight from other plants  Human Influence You Try! Humans add extra nitrogen to the aquatic environment and cause the increase in growth of algae, through the following process: Fertilizers → Excess Nitrogen in Run-Off → Eutrophication → Algal Bloom How could the algal blooms affect the growth of plants in the water? Human Influence  Human Influence Farmer’s Alternatives to Fertilizing: 1. Crop Rotation Some farmers rotate between their regular crops and legume plants Legumes (beans) boost nitrogen content in soils by being the only plants that add nitrogen to the soil  Human Influence 2. Three Sisters Local Haudenosaunee and Wendat have utilized a mutualistic symbiotic relationship for centuries without depleting soil nutrients by planting: Corn - provide a Beans - provide Squash - provides lattice for beans to nitrogen to the soil for moisture to the soil for grow on corn and squash beans and corn  Human Influence 3. The burning of many fossil fuels releases nitrogen compounds into the atmosphere These compounds combine with water and fall to earth as acid rain Destroys waxy coating of leaves which dries them out and makes soil and bodies of water too acidic