In order to see if something is Biotic or Abiotic, think about whether it’s alive or not. Dissolve oxygen is just the oxygen levels in the ocean, it’s not really a living thing. While it does effect the environment, it’s abiotic because it isn’t living. Fish, however, are are biotic because they’re alive.
If you’re ever confused, just think about the basic things all living things have, which is cells, and apply it to the question. Does changing weather have cells? Nope. do trees have cells? Yep!
Also, for the Fertile soil, I said it could be both because of what’s in the soil. Fertile soil has biotic factors in it, like dead animal stuff and dead plant stuff. (Anything that was once living, even if it’s dead, is still considered a biotic by the way). I think your best bet would be to put biotic, but I might be wrong But yeah, in summary, Biotic means living, Abiotic means non living, and in order to see which is which, ask yourself if whatever you’re questioning has cells. Good luck
