Nitrogen in fertilizer is extracted from the air (not from petroleum as stated). The hydrogen can be gotten from electrolysis of water, or from methane.
"In the USA in 2004, 317 billion cubic feet of natural gas were consumed in the industrial production of ammonia... A 2002 report suggested that the production of ammonia consumes about 5% of global natural gas consumption...
Natural gas is overwhelmingly used for the production of ammonia..." — Wikipedia
Yes, but I read the article to imply that we were spreading petroleum on our fields, versus the alternative: rotting garbage. If the argument was an energy argument, I would have expected some mention of energy costs associated with composting (orders of magnitude worse than large-scale energy infrastructure)? The comparison wasn't apples-to-apples, and I wanted to clear up the implication.
So, sure, we use energy to create fertilizer. Instead of mining it and shipping it, or going without. Again, if it wasn't the cheaper alternative we wouldn't be doing it.
