Actually a lot of organic farms rely on blood and bone meal, manure and fish emulsion fertilizers. They're inexpensive as they're byproducts of other industries and are very good for plants.
When I worked in an organic greenhouse I often wondered about how vegans would feel about farmers using animal based fertilizers. We definitely told people what we used, as we sold those products, but no one ever said anything about it. I guess vegans can't control that so maybe it's a nonissue unless they grow their own food and use seaweed based fertilizer(more expensive) instead?

[–] idiomaddict@lemmy.world 1 points 4 months ago (1 children)

If you’ve got the luxury, you can also let fields go fallow and rotate crops to avoid fertilizer. That obviously requires more land though

[–] Danquebec@sh.itjust.works 3 points 4 months ago (1 children)

This thread is weird. It seems like you all never heard of compost.

[–] idiomaddict@lemmy.world 1 points 4 months ago* (last edited 4 months ago) (1 children)

Does that work long term on a commercial scale without egg shells/ bone meal? Afaik, there needs to be an additional source of calcium, but that could of course also supplement crop rotation/fallowing.

Though tbf, limestone is very soft and I could see supplementing with ground limestone.

[–] Danquebec@sh.itjust.works 1 points 4 months ago

Eggs shells don't work unless they're ground into a very fine powder.

I don't know the answer to this question. You may be right. And yea, I can see limestone in the right doses working.

And we could always extract the nutrients from our waste. Close the cycle: what goes in, goes out. We're already using biosolids in agriculture.