I'm guessing rain will dissolve the Milorganite down into the soil.

That being said, Milorganite is not considered an organic fertilizer since it is derived from sewage sludge that contains trace heavy metals and other contaminants. I just mention this since you posted in the organic subforum.

 

I'm must admit I am a milorganite junkie lol it just works. The question I have is that my front walkway and raised bed i have decorative rocks on top of the soil for the trees and shrubs to help with the weeds maintenance. Can I put the milo on top of the rock, will it make its way to the soil?

Well, it kind of depends upon the size of the rock. In general, the larger the rock, the more likely small particles are to make their way down into the soil below. If the decorative rock is generally 2" or larger, I would expect nearly all the milorganite to make it's way down there.

That being said, Milorganite is not considered an organic fertilizer ...

That also depends, but in this case upon which definition of organic one uses -- there are a lot of them for different applications...

 

The rocks are lagers the 2 inches. But milo not being considered organic is something new to me. So what brand then would be considered fully organic. Would that be compost ?

 

But milo not being considered organic is something new to me. So what brand then would be considered fully organic. Would that be compost ?

In my earlier posting, I referred to there being many different definitions of "organic." As to whether or not Milorganite is "organic" for the purpose of taking care of your lawn is, ultimately, up to you, depending upon why you want to use only "organic" for your lawn.

Milorganite clearly feels that their product meets a definition of "organic" as they market their product as being a product for "Organic Lawn Care." (See https://www.milorganite.com/lawn-care/organic-lawn-care)

If you are a farmer seeking to be a "certified organic farmer" than there is an international nonprofit, the Organic Materials Review Institute(OMRI) which certifies products as being "organic" according to their definition. They maintain an official list of their certified organic products on the OMRI Products List.

Some people consider that list as the standard for whether or not something is an organic product, even if it isn't being used to grow food items that seek to be certified organic.

However, unless you are planning to sell your grass clippings as a certified OMRI product, it doesn't really matter if a given product that you use to maintain your lawn is OMRI certified, unless you want it to be.

Ultimately, you, as the lawn owner, get to decide what products you want to use on your lawn, for whatever reasons you deem necessary.

Personally, I try to make lawn care decisions that are good for the environment, which I see as a bit of a balancing act with tradeoffs. Whether or not a product is OMRI certified is not one of my personal criteria, but I respect that others may choose for it to be one of their criteria.