The majority of fertilizer used in the world is the result of the Haber–Bosch process[0] and that requires fossil fuels. Without the ammonia from this process,

The majority of fertilizer used in the world is the result of the Haber–Bosch process[0] and that requires fossil fuels. Without the ammonia from this process, crop yields globally would drop like a stone.[1 see graph, world population vs. ammonia production] [0]https://en.m.wikipedia.org/wiki/Haber_process https://en.m.wikipedia.org/wiki/Haber_process [1]http://sites.psu.edu/shelbyfosterportfolio/wp-content/uploads/sites/34594/2015/09/Shelby-Foster-NHD-paper.pdf http://sites.psu.edu/shelbyfosterportfolio/wp-content/upload...