In the article it is stated 'Nearly half the people on the planet wouldn't be alive if not for the abundant food made possible by nitrogen fertilizer'. I don't believe this. If industrial nitrogen fertilizer had never been available then agriculture would be different in two ways. Firstly, we would be growing more pulse and less grain. Pulses do not need so much nitrogen because they can get it from bacteria in their roots. We would be eating more peas and lentils and less bread and pasta. Secondly, we would not be feeding so much grain and soya to farm animals. We would be eating that grain and soya ourselves. Eating more pulses, we wouldn't need the protein from farm animals. Also we probably wouldn't be eating more protein than we need.
I'm not saying that we should try to do without nitrogen fertilizer. As this article suggests, we should continue to use it, but more intelligently and sparingly. In intensive rice-growing areas of the world, they don't feed much grain or soya to farm animals. So they need fertilizer more than wheat/barley/maize growing areas of the world. Half of the world's wheat, and even more of the barley and maize, are fed to farm animals. African soils often have little nitrogen, so they benefit a lot from it too. However, many Africans can't afford nitrogen fertilizer.
Overestimating the importance of industrially-produced nitrogen fertilizer by writing that half the population of the planet would not be alive without it is not helping the debate. The (human) population of the planet is 7 billion, the pig population of the planet is 1 billion. I doubt that these 1 billion pigs (and however many billion chickens and cattle) would be alive today without nitrogen fertilizer. That would be a good thing, though.