I am reading through the handbook and wiki and it seems like most fertilizers aren't really that good at restoring nutrients, aside from K plants
Bonemeal is N:3, P:30, K:0
Postash is N: 0, P:0, K:60
Saltpeter is N:13, P:0, K: 44
I also read that farmland regenerates nutrients over time. Since fertilizer is either rare, inefficient, or both, compared to how much food you actually need to survive, is it better to just rotate crops into different farm plots?