Straw bale Roof

In Earthbag Building by Kaki Hunter and Donald Kiffmeyer there's a short part about using straw bales as a substitute for sod in a living roof system. See the diagram from the book below.

Seems like a relatively light weight living roof option. I think I would layer it like this:

1) 3/4" Plywood Roof deck (Weight: 2.3 lbs)
2) Polyethylene  Liner (Weight : Neglible)
3) 1.5" Rock wool Comfort board (To protect the liner, Weight: 1 lb per sqft)
4) Straw bales (Weight: ~10 lbs per sqft (dry)

Has anyone done this before? Apart from this book reference and and a mention in The Straw Bale House I haven't seen much about bales on the roof.

If you can turn the drawing around it will be easier to comment

John C Daley wrote:If you can turn the drawing around it will be easier to comment

Sorry John, I didn't get a notification that you had commented. The picture is fixed.

I just got Rob Roy's Earth-Sheltered Houses and he mentions using square hay bales on several of his structures. Seems like an easier proposition then hauling up earth on to the roof. I just wondered why I haven't found much about it on the internet.

I suppose because its different.
I am just reading about a strawbale garden, so we are on a similar path.
Its a novel and easy looking concept.
Here is something I found searching under- strawbales as a roof garden
straw-bale-rooftop-garden
and
straw-bale-gardening/