Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: thedoc on 04/07/2016 22:50:01
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Mary Olson asked the Naked Scientists:
Hello. Wondering about NITROGEN (gaseous) DEPLETION (even fractional) due to pulling so many tons and tons of nitrogen OUT of the atmosphere for artificial fertilizer. I know that the bound nitrogen compounds are BAD-ACTORS in climate, but what about the effective rise of other atmospheric gases when baseline gascious N goes down? Radio Lab (NPR program did a stellar explication of pulling N out of the air...and I, as a specialist on nuclear waste understand the 'enrichment" of uranium idea...so why are we NOT enriching the air with C as we pull out N? And then worse yet, put back N as NOx etc. ? Keep your eye on the gaseous N levels to hear my question. THANKS
What do you think?
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Some plants (like beans) naturally extract nitrogen from the air, with the aid of bacteria-containing nodules in their roots.
However, the amount of nitrogen in the air is so huge (around 80%), and the amount needed in the soil is quite low, so I do not expect any noticeable impact on atmospheric Nitrogen or Carbon Dioxide.
Of more concern, production of man-made fertilizers consumes huge amounts of energy, which does increase CO2 in the atmosphere. The irony is that these fertilizers are applied so inefficiently that most of it washes into rivers, where it causes algal blooms, and into the sea where it disrupts ocean life (including coral reefs).
The bacterial production method keeps the fertilizer close to the roots where it can be absorbed, while enriching the soil for the next crop. No wonder that 2016 has been declared the UN International Year of Pulses (which includes peas and beans).
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This morning I was hiking over mountains that were once covered by glaciers.
Our guide pointed out Lupens (a member of the pea family) and Aspens (a tree) which are both nitrogen-fixing species. These are important pioneer species to colonize areas when a glacier retreats (after the Lichens start to break down the rock).
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There is 80% of 5.26 x 10^18 kg of nitrogen in the atmosphere.
To take this to say, 70% we would need to extract 0.5 x 10^18 kg nitrogen (and obviously something else replaces it)
We use (estimated) 53.2 x 10 ^ 8 kg of fertilizer.. so even if it were pure nitrogen we would still need to try very much harder to put a dent in atmospheric nitrogen. Plus the vest majority of that nitrogen will end up going back into the atmosphere eventually not all as nox's (which aren't products of fuels its the heat of the 'burning' that causes the reaction in the ambient air) and these break down in the atmosphere over time anyway.
Add to this the HUGE deposits of nitrogen tied up in mineral rocks etc. I do not think we have to worry about nitrogen..
If you want to worry about any gasses being depleted in the atmosphere, Oxygen would be the first worry since the impact is much higher and we soak that out of the atmosphere in many many more ways intentionally and unintentionally and the only thing topping it up is hard working plants and algae!