Nitrogen Cycle

• Although the atmosphere is 78% nitrogen gas, plants and animals cannot use this nitrogen because it is unreactive.
• Plants get their nitrogen from the soil by absorbing nitrates. the requires active transport to occur in the roots. The nitrogen compounds can then pass along the food chain through feeding
• Protease enzymes breaks down the protein and produces amino acids.
• all living things require nitrogen to make proteins and DNA.
• For plants to absorb nitrogen it must first be converted into soluble ions, such as nitrates. Nitrogen- fixing bacteria are able to do this. They live freely in the soil or root nodules of some plants.
• When nitrogen-fixing bacteria live in root nodules they are part of a mutualistic relationship providing the plants with nitrates in return for sugars.
• Nitrogen-fixing bacteria are aerobic so aerating the soil will increase the nitrogen fixation.
• Lighting can also convert nitrogen gas into nitrates.
• Plants absorb nitrates from the soil and use these to make proteins.
• when animals eat a plant, nitrogen from the plants proteins becomes proteins in the animal.
• Decomposers break down urea, egested material and dead organisms. The results in nitrogen being returned to the soil as ammonium ions, which nitrifying bacteria can convert into nitrates for plants to absorb.
• Nitrifying bacteria is also aerobic so aerating the soil will increase their impact an increase the nitrate levels of the soil.
• Farmers will use fertilizers to increase the nitrate levels of the soil.
• Denitrifying bacteria reduces the nitrate levels of the soil. they live in water-logged soils. they respire anaerobically as they do not receive enough oxygen. this type of bacteria turns nitrates back into nitrogen.. this returns nitrogen back into the atmosphere.
• Farmers will often aerate the soil to reduce the impact of denitrifying bacteria