1. The Nitrogen Cycle By Eleni, Jaci, Nikki, Rachael and Zac Group 3

2. Definition The Nitrogen Cycle relates to the circulation of nitrogen in a range of forms in nature, in particularly between the atmosphere, biosphere and geosphere. Nitrogen itself is a major component of the atmosphere as 78 percent by volume of the atmosphere is nitrogen gas and in conjunction with this, a series of microbial transformations allows for nitrogen to be available to plants, which enables life to be sustained. Nonetheless, the nitrogen cycle is dependent on bacteria to fix nitrogen in a form that plants are able to take up and can move through the food chain and in doing so some nitrogen is released back into the atmosphere. The steps that are involved in this process include nitrogen fixation, nitrogen assimilation, ammonification, nitrification and denitrification.

3. Main Elements and Compounds  Sulfur Dioxide  Nitrogen Dioxide  Sulphuric Acid  Nitric Acid The nitrogen cycle includes all three biospheres; the lithosphere, hydrosphere and atmosphere

4.  Nitrogen in the atmosphere is found as a gas  Bacteria fix the nitrogenous ions  After the nitrogen goes through organisms, denitrifying bacteria converts the nitrogen ions back to nitrogen gas States/Forms Involved

5. Organisms Involved and Nutrients that Enter the Food Nitrogen is a factor needed by all organisms for the manufacturing of proteins. The supply of nitrogen is a factor that limits the growth of organisms and primary productivity is ecosystems. There are 2 main types of bacteria involved; in the production of chemical nitrogen- its most useful form. These are: - Rhizobium (Large group of heterotrophic facultative anaerobic bacteria, denitrifying) - Anabaena (nitrogen fixers)

6. Main Features  Nitrogen in the atmosphere (approx. 78% is useless to mankind, but nitrogen in chemical form is essential for life  Nitrogen is found in bio- macromolecules, such as proteins and nucleotides – nitrogenous bases in DNA  Nitrogen gas can be fixed to the soil or root nodules of a plant, and then used within an organism  It is also absorbed into the ground and transformed into chemical energy, coming from animal faeces (nitrogenous wastes)  Nitrogen gas is useful when converted to ammonium (ammonification) and then further into nitrates (nitrification)  These transformations only take place when nitrogen- fixing bacteria is present in the soil or plant. These are essential for the entire Nitrogen cycle  Eventually, denitrifying bacteria in the soil releases Nitrogen back into the atmosphere, and the cycle continues.