World Building An Alien Earth... How Much Nitrogen Gas Replacement Can You Get Away With and What Gas To Replace it and Still Have Abundant Life?

[Spacescifi]

Rules: Same oxygen content as normal earth. The nitrogen can be reduced and replaced so long life is not effected so adversely there is no way it can adapt to cope with the change.

 

What percentage reduction is safe and what gas would be safe?

20%? 30% 10%?

I am guessing some less reactive gas.

With less nitrogen plants will be adversely effected and only the hardiest plants will survive.

Meaning on an Earth world like ours they might grow to monster size as they have kess limits on them on their native home alien earth.

Edited May 11 by Spacescifi

[FleshJeb]

I’m a coward, I’d pick Argon.

The major problem is that the nitrogen cycle is necessary for life as we know it. N is a fundamental building block of proteins.

You’d probably want lower concentrations of CO2 as well, because high CO2 negatively affects the uptake of Nitrogen and other minerals, making the plants less nutritious per volume (offsetting the increased volume from the CO2).

Quote

Protein concentrations in plant tissues are closely tied to plant nitrogen status. Changes in plant tissue nitrogen are therefore likely to have important effects on species at higher trophic levels. Performance is typically diminished for insect herbivores feeding on plants grown in elevated CO₂ (Zvereva & Kozlov 2006). This can lead to increased consumption of plant tissues as herbivores compensate for decreased food quality (Stiling and Cornelissen 2007). Effects on human nutrition are likely as well. In FACE experiments, protein concentrations in grains of wheat, rice and barley, and in potato tubers, are decreased by 5–14% under elevated CO₂ (Taub et al. 2008). Crop concentrations of nutritionally important minerals including calcium, magnesium and phosphorus may also be decreased under elevated CO₂ (Loladze 2002; Taub & Wang 2008).

https://www.nature.com/scitable/knowledge/library/effects-of-rising-atmospheric-concentrations-of-carbon-13254108/
 

Did I answer this just to dunk on one-dimensional climate change misinformation…?

I would NEVER.

[Shpaget]

3 hours ago, FleshJeb said:

the nitrogen cycle is necessary for life as we know it

You’d probably want lower concentrations of CO2 as well, because high CO2 negatively affects the uptake of Nitrogen and other minerals

I would presume, if not IRL, certainly if Sci Fi, evolution would have taken care of that. Whatever lifeform evolved in the environment would be well equipped to deal with that environment.

[FleshJeb]

18 hours ago, Shpaget said:

I would presume, if not IRL, certainly if Sci Fi, evolution would have taken care of that. Whatever lifeform evolved in the environment would be well equipped to deal with that environment.

Oh for sure. I just wanted to bring up that the effects of different/changing atmospheric composition are way more nuanced and complex than the usual discussions around them.

As to the lower nitrogen concentration, I’d expect that it would require more metabolic energy to capture each unit. I think this would tend to favor the evolution of slower, more efficient organisms all up and down the chain. On Earth we have creatures that have fascinating adaptations to poor nutrition environments, such as Koalas, Pandas, and Elon Musk. But, they’re all slow, stupid, and require external help to mate.

[kerbiloid]

Even on the Earth the lack of nitrogen is one of the most serious problems for agriculture, solved only in early XX by artificial ammoni synthesis.

If make the nitrogen level lower, the bacteria would have not enough goods to share them with hosting plants.

[farmerben]

The question is relevant on Mars where nitrogen is scarce.  

[kerbiloid]

Everything is scarce on Mars, including the possible agriculture.

No nitrogen - no ammonia. No ammonia - no proteins. No proteins - no most (if not the only) common amphoteric chemical compounds to develop something but the simplest biochemical reactions.

Edited May 13 by kerbiloid

[magnemoe]

On 5/13/2024 at 1:51 AM, FleshJeb said:

Oh for sure. I just wanted to bring up that the effects of different/changing atmospheric composition are way more nuanced and complex than the usual discussions around them.

As to the lower nitrogen concentration, I’d expect that it would require more metabolic energy to capture each unit. I think this would tend to favor the evolution of slower, more efficient organisms all up and down the chain. On Earth we have creatures that have fascinating adaptations to poor nutrition environments, such as Koalas, Pandas, and Elon Musk. But, they’re all slow, stupid, and require external help to mate.

Nitrogen level is so high halve it would not have significant impact, its like high attitude and here oxygen is the main issue 
For plants CO2 is an limit in an greenhouse environment, but very high levels is toxic to animals, high oxygen levels makes fires more likely who will balance it.