Results: In industry, synthesizing ammonia for fertilizers uses massive amounts of hydrogen, typically generated from fossil fuels, but in nature, the nitrogenase enzyme produces ammonia without added hydrogen.
Why It Matters: Producing ammonia for the world’s crop fertilizers consumes 1 to 2 percent of all the energy produced by humankind.
“The Cloud” consumes 2% of electricity in USA. That’s why I give short answers. 
planting legumes and other nitrogen-fixers are good alternatives.
re: pee-cycling(brought up in another post), it is another viable and ‘down-to-earth’ pathway
Providing nitrogen is already in the soil.
It’s a path to pathogens. There’s a good reason it’s illegal in commercial farming. Further, we assimilate nitrogen from the foods we eat so our output is less than our input; i.e. your output is only sufficient for a few leafy produce plants - and the disease risk isn’t worth it. On the other hand, agricultural nitrogen sources harvested from water purification plants will be the wave of the future as mineral deposits of nitrates are exhausted in the coming decades.
don’t legumes(or more specifically, the nitrogen-fixing bacteria in legumes’ root nodules) actually obtain molecular nitrogen from the air, and convert it into ammonia?
Nitrogen fixation using atmospheric nitrogen in most legumes actually only commences when there is little available nitrogen in the soil.
They also process soil-based water-soluble and water-insoluble organic nitrogen (e.g. blood meal, cotton meal) plus nitrate forms in some species. You are correct that the presence of ammoniacal nitrogen in the soil will slow or halt the sequestering of nitrogen from the plant.
More importantly the total output from this activity is grossly insufficient to maintain production rates in commercial agriculture. The world is a hungry place. Presently the U.S. feeds about 2/3 of it. If our population gains continue at present rates, we will only be able feed ourselves by 2050 or so. At the same time sources of Nitrogen are shrinking. This is why the research I quoted above is important.
Enjoyed this post. I do however question the reported fact of the US feeding 2/3 of the world. I find that incredibly hard to believe. Are you talking grain, meat…or what? It’s not as though other countries (most actually) do not employ large scale highly efficient farming.
There’s a department at Cornell devoted to these studies. Many of their reports are public.
what year was this study done?
Numerous reports, for decades.
meehhh…not buying it. Certainly not buying it on those credentials…or lack thereof.
Keep in mind the US (and even us Americans) has a way of overstating their importance in the world. Some (or even a lot) of that attitude has gotten us into a lot of trouble.
Some the studies were commissioned by the U.N., others by Congress, etc. On the subject of world and national agricultural resources these folks are considered the world experts. Check it out for yourself. I’ve been following it for a long time. If You’re asking me to quote a specific report then you’d better be prepared to offer some compensation 
I just thought if you were aware of such a monstrous factoid you might remember where you read it. I’m dubious because the numbers just don’t add up…at all.
I’m not interested in providing compensation for a study based on lies to make Americans feel more important than they are.
Sorry.
Such drama!
What numbers?
Drama…the drama Richard is when we as Americans make outlandish claims about how awesome we are and come off looking like d***weeds when everyone knows it isn’t true.
Fact is…we don’t feed 2/3 of the world, or even anything close to that.
If you’re asking for specific numbers you better be prepared to offer some compensation.
It seems to me your reply is some sort of excuse to not investigate the reports from Cornell. We’d all understand if you don’t want to bother. But to dismiss them without reading a few - that’s a bit disrespectful.
What year Richard…when? Meat, Fish…what? You made the statement…not me.
The US would be exporting what percentage of meat, fish, grains and dairy if only 1/2 of what you said were true? Forget Cornell’s studies…what are we talking about? Your comment read “feed”, so that can only mean what the English language dictates that it means and that is all inclusive.
The US doesn’t feed 2/3 of the world. That would mean feeding 5 billion people and our population is 1/3 billion. That means we’d be exporting roughly 94% of our food production. I’m needing some proof to belief that as well. We’re not exporting anywhere near that much food. I’d say that’s over stated by a factor of at least 10, ie I doubt the US even feeds 0.5 billion elsewhere.