Clay is fertile soil. All you need do is mix in lots of composts to make it more workable.

If this is the first time you'll plant a veggie or flower bed, mix in 4 inches, but only 2 inches at a time.

During each successive season, mix in 2 more inches.

If you want to amend your soil permanently, mix two inches of coarse sand, as well as some compost, into the top six inches of soil with a rototiller. You will then have sandy loam, in which just about anything will grow well. Also, sprinkle a handful of lime on every square foot of soil surface. This will improve soil structure in acid clay soils. I've been using this method for over 40 years, with excellent results. I do another couple of hundred square feet of ground every summer. If you are near Kalama, WA, I can show you before-and-after results. Or you can buy a bag of coarse sand and try it on a small area for yourself. Mix the sand in, then water thoroughly and allow to dry out. If you've added enough sand, the soil won't form a hard crust. You will be able to dig in it with your bare hands. If it's still too hard, add more sand.

You will find that all sorts of mysterious gardening problems disappear when you grow in properly aerated soil. Also, once you've got good soil texture and pH, grass and garden plants will grow well with a minimum of added nutrients, and containerized nursery stock will easily root into the soil. Seed germination will be massively improved. Sandy loam is a pleasure to garden in. If you rake it into raised beds, it gets even better. But raised beds will require more watering.

Here is a link that might be useful: lime and soil structure

Thanks for the replies all. lilydude nope I'm not near Kalama. I'm in the Bellingham area.

one bag of sand is a workable test *only* if you make certain it's at least 2 inches thick over the area where you'll mix it in. (In my region, we suggest 3 inches thick)

When you add enough sand, you only need to add it once.

But you still need to add composted stuff. Every year.

Has anyone tried to improve clay soil with sod as reccomended in Steve Solomon's book"Growing vegetables west of the Cascades". I use his book a lot and most of his advice works for me. So he says SOD is good for improving clay soil. Did anyone tried this method before and what were the results?
Thanks for response.

Sorry, Steve Solomon meant PRODICT NAMED "FINES", NOT SOD, AS i WROTE IN PREVIOUS POST.