If you’re importing manure, perhaps you should import manure producing animals. They self replicate meaning you only have to import a certain number of them and then they create more of themselves. Now that’s sustainability.
I remember small family farms in years gone by that seemed to do OK without Russian chemical fertilizer.
Livestock provided fertilizer as a part of the daily routine.
At the proper time that fertilizer producer met it’s end and produced the meat that is also now in short supply.
Maybe the giant corporate farms aren’t all that they’re cracked up to be.
I always liked the small family farm for the realistic way they operated.