Talk:Nitrogen cycle

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What this page could use is a lovely diagram if anyone artistic is inclined to do so... -- Booyabazooka 03:17, 31 Aug 2004 (UTC)

The current diagram is lovely, but slightly too small to read easily. Suggest using original version (slightly larger)

Done Onco p53 22:45, 5 Feb 2005 (UTC)

i dont understand this, im in high school. could you not make it easier. —Preceding unsigned comment added by (talk) 22:19, 22 August 2010 (UTC)

Human Influences on the N Cycle[edit]

Hi, I'm writing an article to expand upon Human Influences on the N Cycle. I may just make a new page and link this one to it. I'm new to this, so please let me know what you think! ;)

-- I Agree on more about human influences, or perhaps a new category. We talk here about all the negative effects, I want to know overall if this is something people need to be concerned about, and what is or can be done about it. Also what can consumers do to help, like should we be avoiding certain foods like Soy to help solve this dilemma? Are there any foods that we can eat more often to balance the cycle? — Preceding unsigned comment added by (talk) 09:58, 28 November 2014 (UTC)

Also might be worth mentioning the terrible effects on coral reefs esp. farm run-off in Australia. — Preceding unsigned comment added by (talk) 09:59, 28 November 2014 (UTC)

Human influence: currently, this page mainly focus on how harmful human activity has contributed to the cycle by generating more nitrous gas and ammonia due to vehicle emission and industrial agriculture activities. However, this page forgot to mention the positive impact that human aim to create by reducing the nitrite, nitrate and ammonium concentration in surface water in different treatment facilities across the globe. This page also fails to mention the wastewater-as- resource trend in the future for these treatment plants as lots of environmental engineers work hard to reuse the nitrogen in the wastewater and turn them into fertilizer to facilitate the nitrogen cycle.Congluo819 (talk) 00:11, 16 February 2019 (UTC)


This section uses the phrase "several states". If "several states in the U.S." is meant, it should say that, since Wikipedia is international; otherwise if "Several countries" is meant, that would be clearer language.. —Preceding unsigned comment added by Harel (talkcontribs) 21:48, 25 February 2008 (UTC)

“Nitrogen Cycle in Aquariums” Section[edit]

Fact-checking About Nitrobacter[edit]

I'm no biochemist, but I've seen other sources on the web that claim that while Nitrobacter spp. are primary oxidizers of soil-based nitrites, in aquatic environments, Nitrosospira spp. and Nitrospira spp. (which are apparently under a separate phylum or something) appear to play a dominant role.

Here is one research paper that appears (to my chemistry-challenged mind) to assert this: “Identification and Activities In Situ of Nitrosospira and Nitrospira spp. as Dominant Populations in a Nitrifying Fluidized Bed Reactor”

Here is another: Nitrospira-Like Bacteria Associated with Nitrite Oxidation in Freshwater Aquaria”dumboooooooooo

Are there any biochemists out there who have access to current peer-reviewed, journal-published research on this point (and maybe more importantly the know-how to understand the gist of this research and to translate it elegantly into layman's terms)? Thanks! —Iguana Scales 16:24, 11 December 2006 (UTC)


Oops. Well, apparently the “Nitrogen Cycle” subsection under the “Aquarium article” addresses this point nicely. dang you However, the “Nitrogen Cycle in Aquariums” section under this (“Nitrogen Cycle yo mamma”) entry hasn't been updated to reflect these more recent research findings re Nitrospira.

Additionally, the assertions under Aquarium→Nitrogen Cycle aren't accompanied with citations. So I think I'll add the two sources I included above to that article. Anybody with solid biochem credentials can certainly overrule me on this and/or replace my citations with more recent/representative ones. —Iguana Scales 16:48, 11 December 2006 (UTC)

Okay, well I just added the footnoted citations in this section, not the one under the "Aquarium" article. —Iguana Scales 18:37, 11 December 2006 (UTC)

Natural nitrogen cycle[edit]

Does the aquarium-related stuff really belong here? --Satyrium 17:15, 1 August 2006 (UTC)

I personally think there should be a level-two section called something like "Nitrogen Cycle in Aquatic Environments." There could be a few brief subsections under this: "Freshwater-based Nitrogen Cycles," "Saltwater-based Nitrogen Cycles," and "Man-made Applications." (Or a more PC title for the last subsection might be "Human-engineered Applications".)

The last category should cover not just things like hobbyists' aquariums but also applications such as biomass-driven wastewater treatment (see this) and include links to the appropriate main Wikipedia articles/sections that elaborate in greater depth on the topic.

What say all of you? Again, chem/biochem-trained folks, help us out here! —Iguana Scales 17:05, 11 December 2006 (UTC)

ammonia thoughts[edit]

Treatment plants with NPDES permits under the US Clean Water Act are restricted in their (toxic) ammonia discharge, but not their (nontoxic) nitrate discharge. Furthermore nitrate plays a relatively insignificant in eutrophication relative to phosphorus, water temperature and oxygen demanding constituents (raw waste, garbage, fuel, lubricants). I toyed with the idea of a bold rewrite of thissection, but in the end I have to agree that nitrate plays some role in contributing to eutrophication.

Nitrate is bound weakly to an anion exchange capacity comprised mostly of humic substance, another reason why a soil with high organic matter is more protective of the environment than the same soil with low SOM

Denitrification isn't literally the reverse of nitrification or it would produce ammoinium from nitrate.

A exceedingly minor, hair-splitting, point to make here. Nitrogen isn't lost out of the nitrogen cycle to the atmosphere, it is returned and remains within the cycle. A poor comparison but I am reminded of the old adage, you don't buy beer in a saloon, you can only rent it for a few minutes. <soapbox> The oxidative power of nitrate is too attractive for it not to be used by the soil microbial population anytime a flush of metabolic activity causes oxygen demand to exceed supply. That is a good and natural phenomenon to celebrate (its alive!). To bemoan denitrification as a loss is to take a narrow anthropocentric zero-sum mass balance point of view that doesn't have much to do with what the nitrogen cycle really is. </soapbox>

Paleorthid 18:34, 8 January 2006 (UTC)

The article says Nitrogen has contributed to severe eutrophication problems in some water bodies.

I can't recall any specific instances of this being verified, only speculated. I'll search around and possibly amend the above sentence based on what I find. Paleorthid 18:41, 8 January 2006 (UTC)

Probably some way to work this in: Non-parasitic micro-organisms that degrade soil amendments and release nematicidal compounds, such as the bacterium which degrades chitin to produce ammonia (Spiegel et al., 1991), are likely to kill most nematodes in soil. 1 Paleorthid 02:18, 18 January 2006 (UTC)

Why does the article list Ammonia and Ammonium separately? Though they are separate compounds, wouldn't their role in the cycle be the same and could be use sonorously? — Preceding unsigned comment added by 2001:5B0:23FF:3CF0:0:0:0:37 (talk) 00:07, 18 December 2013 (UTC)

what would life be like[edit]

where would we be if 78% of our atmosphere wasnt nitrogen.How would wildlife be complete without Nitogen?I would like everyone to think about these comments.if that russian guy would've not thought about this periodic table maybe we would still all be in some may think im a comedian scientist or maybe just a dumbass but i think im just another curious person who thanks you all very much for reading my comments.PEACE 2 all!

I am not quite sure where this should go under.. but what happens to all this nitrogen that gets fixed? Will we ever run out of nitrogen.. I mean its not exactly recycled into the atmosphere but 'fixed' permanently..

It is recycled, that is why it is the nitrogen cycle. Denitrification converts nitrates to nitrogen. As for what the planet would be without nitrogen, basically on fire as the atmosphere would be almost entirely oxygen. Smartse (talk) 01:42, 11 August 2009 (UTC)

Missing anthropogenic NOx -> eutrophication, foliage damage[edit]

Rather important! See: Fenn, M.E., Ecological Effects of Nitrogen Deposition in the Western United States., BioScience, April 2003, V53 No 4. Scedacity (talk) 15:31, 16 May 2008 (UTC)


The current diagram is incorrect in that it does not show any of the human processes. These now exceed the natural processes and the diagram needs to be changed accordingly. Smartse (talk) 12:20, 16 April 2009 (UTC)

Use this as a source Smartse (talk) 22:30, 31 August 2009 (UTC)

Fixation by Lightning[edit]

Isn't fixation by lightning a significant source of terrestrial nitrogen? —Preceding unsigned comment added by (talk) 18:19, 28 November 2009 (UTC)

Check the link in the above thread, it is a pretty tiny contributor in the scheme of things. The current wording of "Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria." seems ok. We don't have anything about it in Nitrogen fixation though, feel free to add something. Smartse (talk) 21:11, 28 November 2009 (UTC)

Planetary boundaries[edit]

If The amount of N2 per year due to man removed from the atmosphere is a measure of one of the Planetary boundaries. not relevant here, where? (talk) 03:47, 30 March 2011 (UTC)

Before deciding, notability and veracity of this claim should be supported by reliable sources. Materialscientist (talk) 03:52, 30 March 2011 (UTC)

Resource for Planetary boundaries[edit]

Resource for Planetary boundaries:

Why is it appropriate to spam links to planetary boundaries in relationship to each boundary? Just because planetary boundaries, in explaining the subject of the article, links to nitrogen cycle, it doesn't mean that nitrogen cycle should link to planetary boundaries. — Arthur Rubin (talk) 19:42, 30 March 2011 (UTC)
Being a Planetary boundary adds to the notability of the Nitrogen cycle. (talk) 21:29, 30 March 2011 (UTC)
The nitrogen cycle is a well-established scientific concept which needs no further notability to justify a page on it, nor does the not so well-established concept of planetary boundaries have much to contribute. It's the concept of planetary boundaries that needs more notability, and the link on this page seems designed to contribute to that. We don't need this kind of promotion on this page. Let the planetary boundaries page link here, but not the other way round. The statement "an elephant has four legs" is a statement about elephants, not about legs, let alone the number four. Similarly the statement "the nitrogen cycle is one of the planetary boundaries" is a statement about planetary boundaries, not (at this stage) about the nitrogen cycle. Martijn Meijering (talk)
Wikipedia's article Elephant (and Elephant (disambiguation) for that matter) have hypertext wikilinks to other wp articles, so why the one-way argument? (talk) 21:48, 30 March 2011 (UTC)
Pardon me if I am a bit slow, but is this about an Elephant in the room? (talk) 03:37, 31 March 2011 (UTC)
<redacted comment on what the Elephant really is> Still, the last two anon comments are unlikely to be related to editing the article. Could one of them (from that IP) please explain? — Arthur Rubin (talk) 10:48, 31 March 2011 (UTC)

As User:Mmeijeri seems to have dropped the one-way only argument, it is you alone (again) Rubin. (talk) 22:54, 1 April 2011 (UTC)

I haven't dropped it, I've just been busy. Martijn Meijering (talk) 22:57, 1 April 2011 (UTC)
Special:Contributions/Mmeijeri, could you restate your arguement, since as you say you "haven't dropped", please. (talk) 04:43, 22 April 2011 (UTC)
Add The amount of N2 per year due to man removed from the atmosphere is a measure of one of the Planetary boundaries. (talk) 01:22, 3 May 2011 (UTC)
Seems to still be a consensus against, counting all the IPs as the same person, which seems likely. — Arthur Rubin (talk) 01:36, 3 May 2011 (UTC)

With changes at Planetary boundaries, reinstate "The amount of N2 per year due to man removed from the atmosphere is a measure of one of the Planetary Boundaries."[edit]

With changes at Planetary boundaries, reinstate "The amount of N2 per year due to man removed from the atmosphere is a measure of one of the Planetary boundaries." (talk) 04:37, 21 June 2011 (UTC)

I'm still opposed, and "due to man" is not part of the boundary. — Arthur Rubin (talk) 07:50, 21 June 2011 (UTC)
I'm not bothered either way - it seems most relevant in the section on N fixation (since this is the removal of N from the atmosphere) or in the human influences section. Arthur - if our article is to be trusted the boundry is "Limit industrial and agricultural fixation of N2 to 35 Tg N/yr" which are "due to man". If it is included some context about the PBs should be included - I'd never heard of them until seeing the comments above and so I guess that most readers of the article never will have either. SmartSE (talk) 12:44, 21 June 2011 (UTC)
Most readers haven't heard about PBs, because they are a new (2009?) concept, which may not have "buy-in" even in the environmental community. It's also not clear what they are: There are these 7–9 specific boundaries, or are they about the general concept of a "planetary boundary" (which I might consider notable, if someone talked about it). — Arthur Rubin (talk) 18:42, 21 June 2011 (UTC)
I agree. Martijn Meijering (talk) 19:44, 21 June 2011 (UTC)
This is now "Amount of N2 per year removed from the atmosphere by industrial and agricultural fixation", so how about "The amount of N2 per year removed from the atmosphere by industrial and agricultural fixation is a measure of one of the Planetary boundaries"? (talk) 00:25, 22 June 2011 (UTC)
See new excerpt below ... (talk) 19:33, 28 July 2011 (UTC)

With the changes to Planetary boundaries ... Add "The biogeochemical Nitrogen cycle is a Planetary boundaries metric."[edit]

  • Boundary issue Biogeochemical
  • Suggested indicator Nitrogen cycle: amount of nitrogen per year removed from the atmosphere by industrial and agricultural fixation
  • Suggested limit 35 Tg N/yr

Add "The Biogeochemical nitrogen cycle is a Planetary boundaries metric." (talk) 21:25, 23 June 2011 (UTC)

Justification? Notablity of the term "planetary boundaries" as applied to those 9 boundaries, as opposed to the general concept? — Arthur Rubin (talk) 23:21, 23 June 2011 (UTC)
Only seven of the nine are currently defined: metrics. If metricized, not general. (talk) 05:58, 24 June 2011 (UTC)
Add The Nitrogen biogeochemical cycle is a Planetary boundaries metric, with a "nitrogen removed from the atmosphere (millions of tonnes per year)" parameter. 19:51, 25 June 2011 (UTC) — Preceding unsigned comment added by (talk)
Still no reason for the addition; it gives the article "planetary boundaries" more status than it deserves. — Arthur Rubin (talk) 21:32, 25 June 2011 (UTC)
In fact, it even seems designed to do just that, in other words it appears to be POV pushing. Martijn Meijering (talk) 22:23, 25 June 2011 (UTC)
Revised Planetary boundaries has "anthropogenic nitrogen removed from the atmosphere (millions of tonnes per year)" for Control variable. (talk) 23:49, 27 June 2011 (UTC)
Still no reason for inclusion. — Arthur Rubin (talk) 02:19, 28 June 2011 (UTC)
See continuing updating Planetary boundaries Control variable "a) anthropogenic nitrogen removed from the atmosphere (millions of tonnes per year)" [1][2][3]:28–29[4][5] (talk) 01:47, 14 July 2011 (UTC)
Perhaps we could have a unified discussion at Talk:Planetary boundaries to see if any of these are at all plausible. I don't think so, and some editors have reported your (the IP's) edits as disruptive. I don't think that they are intentionally disruptive, but WP:COMPETENCE may need to be kept in mind. — Arthur Rubin (talk) 01:53, 14 July 2011 (UTC)
Speak for yourself, Art, or aren't you already, per WP:CIR ....

Clearly, every editor is incompetent for some subjects, so it is important to know or discover your limitations. (talk) 23:35, 28 July 2011 (UTC)

Some editors are incompetent everywhere. — Arthur Rubin (talk) 00:05, 29 July 2011 (UTC)


  1. ^
  2. ^ The Nitrogen Fix: Breaking a Costly Addiction Fred Pearce, Yale Environment 360, 22 February 2011.
  3. ^ UNEP Year Book 2010: New Science and Developments in Our Changing Environment UNEP, ISBN 978-92-807-3044-9.
  4. ^ Howarth, Robert (2010) Nitrogen Cycle in "Boundaries for a Healthy Planet" by J Foley et al., Scientific American, April 2010.
  5. ^ Earth's nine life-support systems: Nitrogen and phosphorus cycles Fred Pearce, New Scientist, 24 February 2010.

"much of the nitrogen is used in chlorophyll molecules" --> too much emphasis? --> Remove?[edit]

Upon reading the sentence "In plants, much of the nitrogen is used in chlorophyll molecules, which are essential for photosynthesis and further growth." under the 'Ecological function' heading I looked up if the chloroplast molecule has an extreme abundance of nitrogen atoms (and I missed something in school), but it doesn't, just 4 as part of the haem (heme) sub-structure. It seems to overly emphasise the importance of chlorophyll as a nitrogen stock pile. The same could than be said for our red blood cells. I can not consult the reference given "Smil, V (2000). Cycles of Life. Scientific American Library, New York., 2000)" but the author does not seem likely to have a background in molecular plant biology to support this. Can anyone verify if the reference supports this claim? For example by demonstrating that a vast amount of plant biomass is chlorophyll? Otherwise a proteins (with amino acids having C-N ratios between 2:1 (histidine) - 9:1 (phenylalanine) will outdo chlorophyll molecules easily (C:N ratio of 14:1 for chlorophyll a). I propose to remove the entire sentence, as it does not add anything to the section, if it is not true. (talk) 10:44, 21 May 2015 (UTC)

Thanks for pointing that out. It's obviously not correcy as you have pointed out. It's possible that it should have said rubisco (the most abundant protein on earth) instead of chlorophyll, but I can't see the source. It doesn't seem particularly relevant to the cycle regardless. SmartSE (talk) 12:43, 21 May 2015 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Nitrogen cycle/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Considerable editing is still need. Needs improved prose, filling in important gaps on decomposition and units of mass on global scale, clean up references, expand context to better discuss drivers, persistence, effects, and influences. Needs work like all the biogeochemical cycle articles. Of these, carbon cycle looks to be in the best shape and may serve as a partial example of where to go with this article. -- Paleorthid 19:59, 2 December 2006 (UTC)

Nitrogen which forms about 78 percent of the atmosphere, is transformed into nitrates so that the roots of plants can absorb them from the soil. This process of converting nitrogen into a usable form is called NITROGEN FIXATION.When light strikes, nitrogen fixation occurs as nitrogen and oxygen in the air combine to form nitrates.These nitrates are carried to the soil during precipitation.

Last edited at 13:14, 5 January 2012 (UTC). Substituted at 01:19, 30 April 2016 (UTC)

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Environmental Impacts Section Improvement[edit]

I've noticed that the article only talks about the impacts on aquatic environments even though there have been studies showing the impacts it has on various other biomes, so I'm going to try to add some information for the environmental impacts on terrestrial biomes. I'm new to editing wiki pages- this is part of an assignment for a university course but I would like to make as meaningful of a contribution as I can, so please let me know if there's anything that I can do to improve my contributions. I'm consulting a synthesis of nitrogen deposition effects [1] and possibly also an article on American air pollution thresholds [2] that also contains some information about the effects of nitrogen deposition on terrestrial ecosystems, which isn't necessarily America-centric. (I believe I've cited those properly, so please let me know if I've made a mistake in the formatting).Sarahrokosh (talk) 15:31, 3 April 2018 (UTC)


  1. ^ Bobbink, R. , Hicks, K. , Galloway, J. , Spranger, T. , Alkemade, R. , Ashmore, M. , Bustamante, M. , Cinderby, S. , Davidson, E. , Dentener, F. , Emmett, B. , Erisman, J. , Fenn, M. , Gilliam, F. , Nordin, A. , Pardo, L. and De Vries, W. (2010), Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecological Applications, 20: 30-59. doi:10.1890/08-1140.1
  2. ^ Fenn, Mark E; Lambert, Kathleen F.; Blett, Tamara F.; Burns, Douglas A.; Pardo, Linda H.; Lovett, Gary M.; Haeuber, Richard A.; Evers, David C.; Driscoll, Charles T.; Jeffries, Dean S. 2011. Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems. Issues in Ecology, Report Number 14. J.S. Baron, Editor-in-Chief. Ecological Society of America. Washington, D.C. 21 p.

Plants can access organic nitrogen directly.[edit]

It is now known that the terrestrial nitrogen cycle includes the de-polymerization of N‐containing organic polymers by microbial enzymes (such as urease) in the soil ([1]), because all plants (not just legumes) can directly access organic N molecules such as urea. They have evolved specific mechanisms to acquire, assimilate and/or transport them ([2]). Urea can be taken up by both roots and leaves, and plants can compete effectively with microorganisms for organic nitrogen in soil. Nitrification to inorganic ammonium or nitrate is not always necessary for plants to absorb nitrogen ([3]). — Preceding unsigned comment added by Sally Wilkinson Levity (talkcontribs) 12:20, 8 February 2019 (UTC)

Howdy! I plan on adding a new figure that captures the entire nitrogen cycle and is hopefully nice to look at. Any comments or suggestions on what you'd like to see in this image are welcome! M maraviglia (talk) 23:14, 14 February 2019 (UTC)

To say some more: I'd like to incorporate both the land and marine cycles with anthropogenic additions and how those play into the cycle. I think some nice illustrations for all of them will look good and be educational, I'm not sure yet if I'd like to include the oxidation state within this, as it is already covered by another figure on this page. Sorry to double post! M maraviglia (talk) 23:31, 14 February 2019 (UTC)

  1. ^ Schimel, J.P. & Bennett, J. (2004). Nitrogen mineralization: challenges of a changing paradigm. Ecology, 85, 591-602
  2. ^ Witte, C-P., (2011). Urea metabolism in plants. Plant Science 180, 431-438
  3. ^ Ma, Z., Guo, D., Xu, X., Lu, M., Bardgett, R.D., Eissenstat, D.M. & Hedin, L.O. (2018). Evolutionary history resolves global organization of root functional traits. Nature, 555, 94–97