It has been discussed at length in various forums such as compost soil and mulch and organic lawn. I think it has good coverage here in the banana forum since the results of its use on bananas speak for themselves since it is the Sh****t for awesome banana growth.

i have a question how much do you put down and how often do you put it down

Check out my post earlier in the forum about Milorganite and it will give you a good idea of how much, where and when.