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The natural nitrogen cycle

The vast majority of nitrogen on Earth is held in rocks and plays a minor role in the nitrogen cycle. The second largest pool of nitrogen is in the atmosphere. Most atmospheric nitrogen is in the form of N 2 gas, and most organisms are unable to access it. This is significant because nitrogen is an essential component of all cells—for instance, in protein, RNA, and DNA—and nitrogen availability frequently limits the productivity of crops and natural vegetation. Atmospheric nitrogen is made available to plants in two ways. Certain microbes are capable of biological nitrogen fixation    , whereby N 2 is converted into ammonium, a form of nitrogen that plants can access. Many of these microbes have formed symbiotic relationships with plants—they live within the plant tissue and use carbon supplied by the plant as an energy source, and in return they share ammonia produced by nitrogen fixation. Well-known examples of plants that do this are peas and beans. Some microbes that live in the soil are also capable of nitrogen fixation, but many are found in a zone very close to roots, where significant carbon sources are released from the plant. Together these biological nitrogen fixing processes on land, coupled with others that take place at sea, generate an annual flux out of the atmosphere of approximately 200 MtN (megatonnnes of nitrogen or 200,000,000 tonnes of nitrogen). Lightning causes nitrogen and oxygen in the atmosphere to react and produce nitrous oxides that fall or are washed out of the atmosphere by rain and into the soil, but the is flux is much smaller (30 MtN per year at most) than biological nitrogen fixation.

While the inputs of nitrogen from the atmosphere to the biosphere are important, the majority (90%) of nitrogen used by plants for growth each year comes from ammonification of organic material. Organic material is matter that comes from once-living organisms. Ammonification (or mineralization) is the release of ammonia by decomposers    (bacteria and fungi) when they break down the complex nitrogen compounds in organic material. Plants are able to absorb ( assimilate ) this ammonia, as well as nitrates, which are made available by bacterial nitrification    . The cycle of nitrogen incorporation in growing plant tissues and nitrogen release by bacteria from decomposing plant tissues is the dominant feature of the nitrogen cycle and occurs very efficiently. Nitrogen can be lost from the system in three main ways. First, denitrifying bacteria    convert nitrates to nitrous oxide or N 2 gases that are released back to the atmosphere. Denitrification occurs when the bacteria grow under oxygen-depleted conditions, and is therefore favored by wet and waterlogged soils. Denitrification rates almost match biological nitrogen fixation rates, with wetlands making the greatest contribution. Second, nitrates are washed out of soil in drainage water ( leaching    ) and into rivers and the ocean. Third, nitrogen is also cycled back into the atmosphere when organic material burns.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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Source:  OpenStax, Bio 351 university of texas. OpenStax CNX. Dec 31, 2015 Download for free at https://legacy.cnx.org/content/col11943/1.1
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