So in mid 2016 I devoted a pot to being the "citrus dump" which has grown numerous leeks, a complete corn plant, two small broad beans, and is now growing some kale, among a few other things. (Even parsely has started to grow, it is so fertile).
Here's what the pot looked like in August 2016 -
Start of a citrus pot dump - August 2016
It was successful, so in about March 2017, I started another pot of citrus-only mulch.
I will take a pic and update this post on what the result looks like after a year. Short answer: surprisingly fertile, and all sorts of plants are happy to grow in citrus, contrary to the myth of acidity that one hears. Indeed, once one has about 1 inch of rotted citrus in the pot, the earthworms turn up and start eating away as normal. One just has to let the fungus arrive and make the citrus edible by breaking it down.
OK, more later....