nitrogen cycle

• Nitrogen is essential to life, plants and animals need nitrogen to make proteins and proteins that are building blocks of cells and their full life
• Nitrogen makes up 78% of the air, however neither plants and animals can take nitrogen directly from the air because nitrogen is so unreactive
• Plants are able to take nitrogen compounds such as nitrates from the soil and then animals eat these plants, therefore providing animals with a source of nitrogen
• Nitrogen cycle

  Movement of nitrogen for the environment, nitrogen is continually cycled through the air, soil and living things
• Nitrogen fixing

  The process of nitrogen in the atmosphere being turned into nitrogen in the soils
• Ways nitrogen fixing occurs naturally

  • Nitrogen fixing bacteria in the soil turns nitrogen from the air into nitrates which the plants can then absorb
  • Decomposers in the soils break down animal excretion and dead organisms returning nitrogen back to the cell as ammonia
  • Lightning can cause chemical reactions in the atmosphere resulting in nitrogen reacting with oxygen to produce nitrous oxide
  • In the oceans many species of blue-green algae also called cyanobacteria can fix nitrogen
• The Haber process which is how fertilizers are made makes approximately 30 percent of the nitrogen fixing
• Burning fossil fuels adds nitrous oxide to the atmosphere

  Dissolves in rainwater to make nitric acid which then adds nitrates to the soils
• Too much nitrogen in the soil makes it more acidic, the nitrogen also passes into rivers and lakes where it's considered a pollutant
• In some conditions such as waterlogged soils the nitrifying bacteria in the soil break down nitrates and return nitrogen back to the air, this reduces the fertility of the soil
• nitrogen cycle