If you want to use less or zero toxins in your fertilizers, then don't rely on the terms "organic" or "certified organic". These labels usually mean something different than the purveyor would have you believe.
Farming is an un-natural made-made discipline. If you want to do something natural, then participate in habitat restoration. If you live in the southwestern U.S., then these folks have lots of non-subjective information to get you started:
Tree Of Life.
Sbl, you are correct that mulching is a poor choice for citrus in your climate and soil. In my less-humid environment here, it is a necessity but of course soil drainage is also needed.