Huh. That's actually pretty neat. Math time!
So for a fully automatic fertilizer operation, I'd need to first make a ender spawner and collect a stack of enderpearls. This gives me 16 dusts which I can electrolyze for 4 potassium and nitrogen, which makes 20 saltpeter when combined with compressed air. But then I'd need tin to make the cells... I guess I could centrifuge lava cans. 32 of the forestry type since it's not nerfed by Gregtech, or 32 of the red nether cans once the nerf hits will create a surplus of 4 tin that can be used to make 16 tin cells.
...But I'm still missing cells as I need to make compressed air as well, so let's make that a stack of lava to create the tin. Magma Crucible at this point would take way too much energy, so we should look into alternatives. Sulphur from netherbees in a squeezer would work nicely since we're already using nether bees to make the refractory capsules (probably). Pulverize cobble from a cobblegen to make the sand needed.
Throw it all in the cooker, and we end up with 20 saltpeter. Unfortunatly, we still need more stuff to make the fertilizer, which requires more sand and dirt. the sand is easy, but we need to find a way to get 40 dirt as well, to create 40 fertilizer. Only way I know of making dirt is plantballs, but 40 plantballs is ...5 stacks of plants. Not impossible, A wheat farm could probably supply that easily enough though. Maybe a peat bog could supply it? Hm.
All in all... Not impossible... But I think I'll stick with the Apatite
(Fake)EDIT: Actually, we could simplify a bunch by making tin from Extra Bees, we'd only need 8 combs to make the tin we'd need, which is a lot easier than getting 64 lava from sulphur + all the other stuff... All of a sudden things are much more viable! I'll leave in what I wrote already because I'm lazy and stuff. Still, making dirt is a pain... Anyone know of a good way?