Hi Frogdoc, it sounds like you bought a chunk of Florida beach. Can you tell us where you are?

You can improve almost any soil with organic matter obtained from compost dug into the soil or mulches placed on top. What's in your giant 'mulch' pile? Do you have a compost pile yet?

What are you planning to grow in the garden, and how big is it?

And thanks for leaving all that clay behind for the rest of us Missourians. Trade ya a truckload! :-p

Yes. Tox is right 100%

Get one truck load of compost and till it in. The soil will be good in no time.

Go 3 minutes and 40 seconds in the vid-http://www.youtube.com/watch?v=sohI6vnWZmk

They talk about how they took the salt out of the soil and made it perfect with mulching with organic matter.

If you were to buy "topsoil" what would you expect it to be?
As both of the previous postes have stated there is no good reason to buy something called "topsoil" when what your soil needs is organic matter. Look for a source of compost, leaf mold, or for many of us the leaves that fall from trees that most people simply throw away.
The soil I have here is Lake Michigan beach sand and amending that with 6 to 8 percent organic matter, compost, shredded leaves, cover/green manure crops, any kind of vegetative waste, has made it into a soil that will grow things quite well.
If you were able to find some really good "topsoil", something closely approximating 45 percent sand, 25 percent clay, 25 percent silt, and 5 percent organic mattere, adding that to the soil you have will mean there is much less organic matter then you want and you would still need to find some organic matter.

You may get great topsoil with no weed seeds, but It is more likely you will get sand with a little soil mixed in to color it. I know of only one topsoil with compost mixed in it, & the vender does it because the compost is free & is a filler to starch the soil he sale.
You are better off buying compost, but get a sample from the vender & have it tested first.

Just improve the SOM! :)

The link below is an episode of Growing a Greener World that interviews Elliot Coleman and what he did to make their farm into a Four Season Farm, including amending the soil.

Here is a link that might be useful: GGW 301