Much of the world was starving without the development of ammonium nitrate fertilizers. This lead to quite a few political uprisings by starving peasants which eventually forged modern governments.
The demand or need for chemical fertilizers became an imperative by the Germans during WWI. They were running out of nitrates formed from animal based ammonia and they had been importing slatpeter from Chile. When war broke out, other nations banded together and cut off their supply. Theri need for ammonimum nitrate was not to feed their people, but to make explosives.
WWI would have ended much earlier had they not assembled different processes to make ammonia from the air and then converted it to usable ammonium nitrate on a large scale. They now had the material to make bombs and fertilizer to feed their people and troops.
After the war, the world became indistrialized and with the post-war baby booms, people realized they had to produce more food to feed the much larger populations in the cities. They saw value in the streamlined processes developed by the germans.
And now we live in a world where our poor are overweight!
But the quality of food is not as good. You can produce tons of sugar and starch crops, but the minerals are being depleted from the soils at an amazing rate. Indistrial acid rain also leaches more from the soil as well - rain water is not as pure as some would like you to believe.
In theory, the cycling of manure sounds elegant, but over the long run you may end up concentrating toxins, naturally made animal hormones, and even biological pathogens in a particulare area.
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IF you can read this, thank a teacher. If you are NOT reading this in The King's English, thank a veteran!