We are not remotely this dependent on natural gas to produce nitrogen fertilizers: you can inject green hydrogen near the end of the Haber process, skipping the methane cracking step by cracking water instead. Haber is only the dominant process because of its enormous externalities.
It is baffling how these peak oil guys can keep a readership when every other claim of fact is a howler. Like, are gas prices really "getting higher and higher"? Who has time for this stuff?