[My Foot Smells]

kchd, I'm not really an expert, but I can tell you what I used. I have a whoiesale supplier and a 3 axle dump truck driver (think 18 ton) that I use. the mix was a 70/30 compost/green sand. I also used some perlite that I can get for free.

my experience with a straight top soil is that it held too much water and I had problem with fungus and disease. too heavy without a mixer. the sand helps with the drainage, but holds just enough moisture. topsoil does well outside of the box though, but in the box got thick.

some places do a 60/40 mix of like matters. I also live across from a horse farm that I can get aged manure, but the ants love the stuff too and have had problems w/ the ★★★★ ants nesting in my pile.

in subsequent years, I have either added another heaping of the "supersoil" mix, or just a 4" layer of compost, as the bed shrinks down in existing soil, or decomposes further. I can trailer small loads.

I live by a river and live on top of modeling clay. Certain bulbs do ok, but looks like topography of Minnesota after a rain (land of lakes). holds water like a bucket. Thus the RB, which has done well.

I've got 11.5", 18", and 22" beds throughout. the higher bed saves my back, but can't vouch it is more ethical than the 18". the shorty I don't plant deep species.

Str8 compost may be too "hot" the first year, and it might make a difference to what your native soil composition is. Seems like there would be some kind of silty-compost mix in your area. Mississippi (like Arkansas) can get some heavy, heavy periods of rain in the spring; so I would rather have drainage that something that will take 2 months to sunday to dry out. I usally run some leaky hose on top of bed, so I can drink a beer & water at the same time. LY, I didn't whip out the hose almost until June - got so much water.

Once again, this is just an opinion.