Maybe this article might be useful for the purposes of the discussion:
N. Nitrogen. Atomic number seven. Unnoticed, untasted, it nevertheless fills our stomachs. It is the engine of agriculture, the key to plenty in our crowded, hungry world.
Without this independent-minded element, disinclined to associate with other gases, the machinery of photosynthesis cannot function—no protein can form, and no plant can grow. Corn, wheat, and rice, the fast-growing crops on which humanity depends for survival, are among the most nitrogen hungry of all plants. They demand more, in fact, than nature alone can provide.
Enter modern chemistry. Giant factories capture inert nitrogen gas from the vast stores in our atmosphere and force it into a chemical union with the hydrogen in natural gas, creating the reactive compounds that plants crave. That nitrogen fertilizer—more than a hundred million tons applied worldwide every year—fuels bountiful harvests. Without it, human civilization in its current form could not exist. Our planet’s soil simply could not grow enough food to provide all seven billion of us our accustomed diet. In fact, almost half of the nitrogen found in our bodies’ muscle and organ tissue started out in a fertilizer factory.
I think I remember rightly that industrial processes have doubled the amount of nitrates in global circulation. When the petroleum products which supply that extra fertility get too expensive and/or difficult to extract it’s going to become impossible to sustain that population of 7+ billion human beings no matter what methods are attempted. There’s just no way to get the same amount of calories out of the planet’s solar budget as modern agriculture has been able to do by exploiting the millions of years of solar energy that has been concentrated into oil & gas. So much the better if you ask me!