Nitrogen cycle Series of natural processes by which nitrogen passes through successive stations in air, soil, and organisms. The atmospheric nitrogen occur in an inert form (N2)/can’t be used by most of the orangnims. Atmospheric nitrogen is fixed by nitrogen cycle. Which principally invovles:- Nitrogen fixation. Nitrification. Assimilation. Ammonification. Dentrification.
Nitrogen fixation:- Deposits into soil & surface water precipitation. Once settled; undergo changes Conversion via Microorganisms: Bacteria in symbiotic relation with plants. Free aerobic bacteria/alga. Cyanobactetria
Nitrification:- Two step process; converts NH3/NH4+ to NO3. In first step:- Nitrosomanas/nitrococcus (soil bacteria) convert NH3 to NO2-.
In second step:- Nitrobacter converts NO2- to NO3-. Bacteria gain energy known as ( nitrifying bacteria).
Assimilation:- Process by which plants/animals take up nitrates and ammonia. Plants take up NO3- and NH4+ through their roots and integrate them into various plant proteins /nucleic acids. Animals take up this nitrogen by consuming plant tissues.
Ammonification:- Many bacteria and fungi convert nitrogen into ammoniumNH4+ known as ammonification. Converted ammmonia become available to take part in other biological processes.
Ecological Implications of Human Alterrations to Nitrogen Cycle:- Burning fossils fuels. Primary productivity of many ecosystems. Alterations in both aquatic/terrestrial ecosystems. Argicultural systems (leach out of soil) Haber-bosch process. Anoxio/hypoxia. Harmful algal blooms. Change in boidiversty/overall ecosystem function. Parasitic/infectious diseases (humans/wildlife). Increased acidification in freshwater ecosystems.