Explain the Nitrogen cycle
There are many sources online written at various grade levels. Perhaps this one will help:
http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/nitrogencycle.html
I recommend reading several that you easily find by using the search words "nitrogen cycle" . You will probably find one to your liking.
Already answered.
http://www.jiskha.com/display.cgi?id=1352679613
The nitrogen cycle refers to the continuous process by which nitrogen is converted and recycled in the environment. It involves several steps:
1. Nitrogen fixation: The cycle begins with nitrogen fixation, in which certain bacteria (known as nitrogen-fixing bacteria) convert atmospheric nitrogen (N2) into a form usable by plants. This can occur through biological or non-biological methods. Biological nitrogen fixation involves symbiotic relationships between certain bacteria and plants, such as legumes (e.g., soybeans, peas) or non-leguminous plants (e.g., alders). Non-biological fixation occurs through industrial processes like Haber-Bosch process, where atmospheric nitrogen is converted into ammonia (NH3), which is the most common form of fixed nitrogen used in fertilizers.
2. Nitrification: Once nitrogen is fixed into usable forms, it can be taken up by plants. Nitrogen is primarily absorbed by plants in the form of ammonium (NH4+) or nitrate (NO3-) ions. Nitrification is a process carried out by nitrifying bacteria. These bacteria convert ammonium into nitrite (NO2-) and then into nitrate through two separate reactions. Nitrate is the primary form of nitrogen utilized by most plant species.
3. Assimilation: Plants take up nitrate or ammonium ions through their roots and use them to synthesize proteins, DNA, and other nitrogen-containing compounds essential for growth. In this stage, nitrogen becomes incorporated into the plant's tissues.
4. Ammonification: As organisms, including plants and animals, die or excrete waste products, nitrogen is released back into the environment in the form of organic nitrogen compounds. Decomposer microorganisms, such as bacteria and fungi, break down these organic matter and convert them into ammonium ions through the process of ammonification.
5. Denitrification: Denitrification is the final step in the nitrogen cycle, where certain bacteria convert nitrate back into atmospheric nitrogen (N2). This occurs in anaerobic (oxygen-limited) environments, such as wetlands or waterlogged soils. Denitrifying bacteria use nitrates as an alternative source of oxygen, releasing nitrogen gas back into the atmosphere.
Overall, the nitrogen cycle helps ensure a continuous supply of nitrogen for living organisms and plays a crucial role in the balance of nutrients in ecosystems.
The nitrogen cycle is a biogeochemical process that describes the movement of nitrogen through various systems in the environment. It involves the conversion of nitrogen between different forms, such as organic and inorganic compounds, and its availability for different organisms.
To understand the nitrogen cycle, let's break it down into several key steps:
1. Nitrogen Fixation: The process begins with nitrogen fixation, where atmospheric nitrogen (N2) is converted into a usable form by certain bacteria called nitrogen-fixing bacteria. These bacteria can be free-living in the soil or form symbiotic relationships with certain plants, known as legumes. Nitrogen fixation can also occur through industrial processes, such as the Haber-Bosch process, which produces synthetic fertilizers.
2. Nitrification: Nitrogen fixation converts nitrogen gas into ammonia (NH3) or ammonium ions (NH4+), which can then undergo nitrification. Nitrification is a two-step process performed by nitrifying bacteria. Firstly, ammonia is oxidized into nitrite ions (NO2-), by bacteria called ammonia-oxidizing bacteria. Then, nitrite ions are further oxidized into nitrate ions (NO3-) by bacteria called nitrite-oxidizing bacteria. This conversion process makes nitrogen more readily available to plants.
3. Assimilation: In this step, plants or other primary producers take up the nitrate ions from the soil and incorporate them into organic compounds, such as amino acids and proteins. This process allows plants to utilize nitrogen as an essential nutrient for growth and development.
4. Mineralization: When plants or animals die, or through the excretion of waste products, organic nitrogen is returned to the environment. Decomposer organisms, mainly bacteria and fungi, break down these organic compounds and convert them back into inorganic forms, such as ammonium ions. This step is known as mineralization or ammonification.
5. Denitrification: Some soil bacteria perform denitrification, where nitrate ions are converted back into nitrogen gas (N2) and released into the atmosphere. This completes the cycle and maintains the balance of nitrogen in the environment. Denitrification occurs in oxygen-poor conditions, such as waterlogged soils.
Overall, the nitrogen cycle plays a crucial role in maintaining the availability of nitrogen for living organisms. It is a dynamic process that involves both biotic and abiotic factors in different environmental compartments, including the atmosphere, soil, water bodies, and living organisms.