

4 most important parts of artificial fertiliser are nitrogen, phosphorus, potassium and sulfur.
Nitrogen is Infinite. It’s made from the air which is 78% nitrogen. Energy is needed to fix it. Usually its natural gas but it doesn’t have to be. Electricity can also be used. There are real world plants who use hydro or wild energy to make it, even if they are few today.
Phosphorus is plentiful on Earth, both in soil, rock and sea water. However in most natural sources the concentration is too low to actually refine today. Phosphate rock which is the main source today is limited. 70% of the current Reserves are in one single country, Morocco. All world reserves combined should last for a our 300 years. After that we will either have to extract phosphorus from less phosphorus dense sources or we have to recycle it better from human excrete. Nevertheless we have plenty of time to come up with that technology. Main problem right now is not it running out but the risk of how concentrated it is. What if Morocco doesn’t want to share?
Potassium is extremely plentiful around the world. It’s 2,6% of the Earth’s mass and even the potassium rich minerals we currently use are expected to last hundreds if not thousands of years. Mined all over the world but mostly in Canada, china and Russia and Belarus. Not really a problem. Also plentiful in seawater.
Sulfur has many different sources and in most it’s a byproduct. Main source is as a biproduct of refining fossil fuels but it’s also created as a byproduct of mining for other minerals. The amount needed for agriculture is also comparably small. There is so much sulfur out there it’s even mixed into concrete just to get rid of it. I don’t see sulfur as a main concern.
So to summarize I’m really not concerned about any of them except for phosphorus and for that one it’s mostly the question of how willing Morocco is to share it. Long term when sulfate rock runs out 300 years I’m quite secure we have found out how to commercially extract it from a less dense mineral. Either that or we have finally started seriously recycling it from human excrete. Phosphorus is very easily recycled. The technology is already here. More sewage plants would just have to do it. And if we are starting to slowly reach peak phosphorus the pure financial incentives will make sewage plants start recovering it. Now it doesn’t happen because the mineral phosphorus is just too cheap and convenient.





There are many different kinds of farms and they all need different inputs. Most impacted would be the corn and soy farms who produce a low value good for a lot of inputs in the form of fertilizer, seeds, sprays, fuel for heavy machinery etc. Least impacted would be beef producers who use wild grazing. Almost no inputs as the land produced the grazing by itself, at the same time they produce a high value good.
Of course there are lots of intermediates but those would be the extremes.