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Nitrogen makes up most of our atmosphere, it gets fixed by bacteria, legumes, etc., and enters the soil in a different form to be used by plant life. The nitrogen gets buried in sedimentary rock over time until it is released into the atmosphere by tectonic activity. Nitrogen in the soil is a limiter, in most places there's more growth and plant activity than there is in the soil. Increasing the supply in the soil could change soil composition in a good way or eventually at a high enough rate I am sure in a bad way. On earth nitrogen can negatively effect certain ecosystems so I would expect plant life on a world to evolve differently. I also know that nitrogen narcosis puts the limit on pressure at 2-4 Atmospheres for humans. So I ask how much more nitrogen in an atmosphere and soil could an alien world have, and what kind of changes to plant life or the equivalent would people see. I don't think I want more than 2 bar or atm.

Edit: logging in through gmail is a hassle, anyways, the Question is somewhat correct, and somewhat wrong. There is a large amount of activity within the nitrogen cycle, but after looking at the surface has to offer, it appears that we should focus first on nitrates and nitrites in the soil. These have limits for plant life, eventually too much in the soil will prevent plants from finding anything else it needs, and it can lead to "root burn" or damage to it's leaves. There is also the question of storage and how much can the soil store before runoff becomes an issue. The answer and another place to store the nitrogen is within the plants themselves, it is possible as mentioned by myself that instead of increasing atmospheric nitrogen it could be drained for resources. So a better two questions would be in what ways can Plant or Fungal life use more nitrogen and how can we change nitrification or denitrification in a system Some answers would be to change photosynthesis and the use of sugars, cellulose, or really anything that a plant uses Carbon for.

So some possibilities would be in replacement of glucose with something that uses more nitrogen as energy storage seems to be a significant source of a demand for carbon in a plant, this is a good place as leaves use CO2, and the source of demand will be where it could take in N2.

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closed as too broad by Mołot, Renan, kingledion, anon, elemtilas Nov 14 '18 at 2:29

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ The word "in" has two very different meanings in the phrases "nitrogen in the air" and "nitrogen in the soil". The air actually contains nitrogen,; this is a mostly chemically inert gas, of which the main function is to serve as a buffer moderating the reactivity of oxygen; plants cannot use it. The soil contains ammonia and/or nitrates, nitrogen compounds which can actually be used by plants. Nitrogen from the air is converted to ammonia and/or nitrates by certain bacteria, and, most importantly, by large factories using the Haber process. $\endgroup$ – AlexP Oct 8 '18 at 16:10
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    $\begingroup$ Um I'm not seeing an actual question in the question here, what information are you after exactly? $\endgroup$ – Ash Oct 8 '18 at 17:01
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    $\begingroup$ Related: Can plants thrive without atmospheric nitrogen? $\endgroup$ – Alexander Oct 8 '18 at 17:55
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    $\begingroup$ @BlindingLight "Putting more in the air will lead to more in the soil" - not necessarily. It's not like the amount of atmospheric nitrogen is the limiting factor for nitrogen compounds production in the soil. $\endgroup$ – Alexander Oct 8 '18 at 18:22
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    $\begingroup$ @BlindingLight Raw nitrogen is basically saturated; it's not the limiting factor in the nitrogen cycle. The limiting factor is that a) living things have to spend energy to fix nitrogen, and they're not at all keen to waste it making more than they need, and b) excess oxygen is bad for the fixation process, so these organisms tend to be a little complex. The more "fixed" (usable) nitrogen there is, the worse they perform next to non-nitrogen-fixing organisms, so the cycle is self-limiting. $\endgroup$ – Cadence Oct 8 '18 at 21:47