It is basically the circular pathway in which chemical elements circulate in the biosphere. The part of earth where we live is called biosphere. Because the nutrients circulate from organism to environment and from environment to organisms.
And there are two basic types of biogeochemical cycles:
In this cycle, the reservoir is atmosphere.
In this cycle the reservoir is earth crust.
There are different cycles. Some are discussed below:
79% nitrogen is present in the atmosphere. Plant cannot absorb nitrogen directly instead they first convert it into nitrates then use it. There four steps of nitrogen cycle. We discuss it one by one.
The conversion of nitrogen into ammonia and nitrates, this process is called nitrogen fixation. The fixation may be non-biological or biological.
Due to lightning and electrical discharge in clouds nitrogen fixed and this non biological fixation.
Hence Fixation which occurs due to the activity of mutualistic bacteria called biological fixation. In this living organisms involved.
So The conversion of nitrogen into ammonia called ammonification.
By the activity of nitrifying bacteria, the ammonia converted into nitrites and nitrates.
In Case of By the activity of fungi and bacteria, the nitrates converted back into nitrogen. This is called Denitrification.
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