In the biosphere, the main nitrogen-containing nutrients include:
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NH4+ (Ammonium) - Ammonium is a key form of nitrogen that can be directly taken up by plants. It is often produced through the decomposition of organic matter, as well as through specific processes like ammonification.
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NO3- (Nitrate) - Nitrate is another important form of nitrogen that is readily available for plant uptake. It results from the nitrification process, which converts ammonium into nitrates. Nitrates are often the predominant form of nitrogen found in soils.
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N2 (Nitrogen) - Atmospheric nitrogen (N2) makes up about 78% of the Earth's atmosphere but is generally not directly usable by most organisms. However, certain bacteria (nitrogen-fixing bacteria) can convert atmospheric nitrogen into forms that are usable by plants, such as ammonium.
These nitrogen forms play crucial roles in various biochemical processes and are essential for the growth and development of plants and organisms in the biosphere.