The Haber-Bosch process, which produces ammonia from nitrogen and hydrogen, is crucial for nitrogen fertilizer production and supports approximately 50% of the global food supply. This estimate is based on:

While this figure is widely cited, its exact origin is difficult to pinpoint because it is often aggregated from multiple studies. For deeper insights, reviewing Smil’s work, FAO reports, or comprehensive studies on nitrogen's impact on global food security is recommended.

I find the same sentence in a schools competition article published in The Oxford Scientist with the title 'The Haber Process: A simple Discovery that changed the world .The Oxford Scientist June 1,2020 by Mukhtar Quraishi

The sentence given is " In fact,nearly 50% of the nitrogen found in human tissues originated from the Haber-Bosch Process(Solomon,P.M.-2004)."

It was also mentioned in an another article 'The Haber-Bosch Reaction:An early chemical impact on sustainability by Steven K. Ritter C&En August 18,2008

The last paragraph of the article mentions that the chemical fertilizers contribute about half of the nitrogen input into global agriculture,while biological nitrogen fixation taking place in leguminous plants contributes the other half.That means about half of the nitrogen atoms in the body of an average person living in a developed country once passed through a chemical plant and participated in the nitrogen to ammonia Haber-Bosch reaction.

Hey thanks heaps Annangi. I had found both references but was too slow to connect human produced fertilisers with the haber bosch exclusively - i should have realised that if the ammonia from the haber bosch process is used to create urea and ammonium nitrate, then perhaps that is the sum total of human produced nitrogen chemical fertilisers.

@ Al Hall We have only two major sources of nutrients to plants and microbes(subsequently to animals and humans) the N fertilizers from Haber and Bosch process and biological N fixation in legume roots in symbiotic association with N fixing bacteria in soil.Non-symbiotic N fixation by soil microorganisms is also in operation in soil. Ammonia synthesized in Haber-Bosch process is key component of all N fertilizers used in agriculture.

Annangi I have been reading also, that quarried fertilisers such as cave Nitre and ammonium nitrates from rocks in fertiliser quarries also are dwindling supplies. I think there are still compacted and ancient rock deposits formed from bat and bird guano that are mined but, I have not as yet found estimates of when these supplies will be used up?

Al Hall As you may be aware by this time by consulting literature that bat guano,chilean saltpetre common name sodium nitrate and calcium cynamide common name nitrolime were used as fertilizers in earlier times before the Haber-Bosch process based fertilizers became available or popular.Those earlier products have limited supplies and have lot of alternative uses.Sodium and potassium nitrates have multiple uses from food, medicine to many other .Among them Bat guano appeared to be still in use in countries where it is available.Ammonium nitrate and calcium ammonium nitrate are also being used as fertilizers but their source of N is Haber-Bosch process. I find a review article on Bat manure in researgate.net/publication/372034912 Doi:10.33736/bjest.5100.2023

Borneo Journal of Research Scienc....13(1)22-31

Thanks indeed for the fascinating article Annangi - your reply prompts further thought! The table of yields by species in the article are thought-provoking (I accessed the article via the doi you provided, as the link itself only brought up a blocking page at my side). The Nitrogen yield for species that eat primarily insects, makes me wonder if we could utilise insect composts/fertilisers directly to attract the same yields...without climbing into bat caves to get the "rainbow cake" of layered deposits that the article describes :)